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Basic disinfection of potable water in 3rd world

Basic disinfection of potable water in 3rd world

Basic disinfection of potable water in 3rd world

(OP)
Help
I'm not a water expert, just a humble engineer working on the borders of Laos/cambodia.  We have a simple rain water harvesting system collecting into 5000l cement jars - a long established practice. However we do get outbreaks of jungle belly which I believe is due to poor management of the jars (I smelled and tasted the water).  They dont practice roof flushing of first run off (for 10 mins say). we have a lot of birds and worse, the jungle chickens.  they dont have effective covers over the jars, they dont flush out the gutters (not easy), we have a lot of trees and leaves.

It seemed to me that 4 drops of household bleach (sodium hypochlorite 5%vv) per litre would help sanitise the water but I cant find anywhere on the net that admits this as an ok practice. Do you see any problem with this?
Once the water is disinfected it should stay that way (assuming the covers are in place and no new rain arrives. After a week or so the chlorin will have gone anyway.

If this is ok, why dont they use this in Bangladesh, say?
Its cheap and cheerful. All this pious advice about boiling water for 15mins is of no use when you dont have firewood.

Secondly I was proposing to use a simple form of sand filter for the local pond/river water which is sometimes available, mainly to remove turbidity and vegetable matter, then dose with bleach. Any comments on this

Please excuse my ignorance if I am stating the obvious here. Its very frustrating to read the learned dissertations from 3rd World water.org to find they have told you nothing useful

Your guidance may reduce the incidence of child jungle belly, which I also get sometimes.

RE: Basic disinfection of potable water in 3rd world


It is a long time since I used bleach as a disinfectant in Sudan. I recall using 6 drops of houshold bleach per gallon of water as the rule of thumb. (Houshold bleach contains about 5% free chlorine (Sodium hyperchlorite). Industrial bleach may contain 15% and will  require only 2 drops. The container needs to be shaken to give adequate contact. I think the danger is if your water includes rotting vegetation chlorination may end up producing toxins but I am no expert. I can only say that we used bleach in Sudan and as far as I can recall it did not have an adverse health affect on the local population.


However, I would suggest UV disinfection using clear plastic bottles is a safer alternative. Stand the water in sunlight for 24 hours before it is used.

Brian

RE: Basic disinfection of potable water in 3rd world

The bleach available here is 12%.

I would use it to disinfect the containers.  I have never used it to actually disinfect water per se, but if others have used it the basic principals would remain the same.  However, this would be subject to the cleanliness of the water in the first place.  If there is a high organic loading (rotting vegetation) then in the long term, you could be creating more problems by the toxic compounds resulting from the chlorine and the organic reactions.  I disinfect my motorhome system annually with bleach and water, as well as swabbing valves and pipe repairs in water distribution systems, and therefore have direct knowledge of it's application.

You should ensure the vessels are meticulously cleaned and disinfected.  Splash and scrub them with the bleach, if it's plentiful.  The water should be as clean (even filtered) as possible to remove as much undesirables as possible, given your circimstances.  

Then add the drops of bleach to the collected rainwater in the cleaned and disinfected vessels.  I have never added bleach to water to disinfect and provide some residual chlorine and therefore have no idea as to how much to use.  I do know however, that some bleach contains "fresheners, whiteners and other types of fragrances and soaps" and those are not recommended for usage in a consumable "potable" system.

KRS Services
www.krs-services.com

RE: Basic disinfection of potable water in 3rd world

cvg,

Very, very good website....thanks for your reply to this thread.  And I stand corrected...the bleach here is 4.5%, not 12%.  

The BC government finally did provide some useful info....LOL.

KRS Services
www.krs-services.com

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi guys
Many thanks for your inputs, also agree the site is vg and down to earth, no bs!
I would consider using a sand filter to remove obvious vegetable matter and turbidity and have read up on the effect of bleach and the production of THMs trihalomethanes
Rain water harvesting does not normally suffer from this unless overhanging leaves prevail. Ther is the problem of guttering however which never gets cleaned?

The second water source comes from ponds which are excavated to provide high ground, 250mm above the paddy field floods. These are often used as fish ponds to raise catfish varieties. I believe this water could also be made potable with sand and bleach. However, big warning here, you must keep ducks away from the water, they are serious polluters with some unpleasant parasites in their faeces.

What I cant understand is why these simple remedies are not recommended as reasonable practice under the prevailing circumstances?  I have spent several days searching the net on this subject and come up against a brick wall of pontificating self serving academicos - if I may be so blunt

Not an ounce of use to the average poor family with chronic diarhheoa from poor water quality. Im in the swamps of thailand at the moment, relatively benign, but my time in Nigeria was a mightmare.

RE: Basic disinfection of potable water in 3rd world

> What I cant understand is why these simple remedies are
> not recommended as reasonable practice under the
> prevailing circumstances?

Yeah, I can understand that...

If I recall correctly, the MIOX process (www.miox.com) was developed as a low-tech, expedient purification process. I can't find a reference, but I recall something about the U.N. or W.H.O. testing the method (maybe not the brand) for exactly your type of locale. They added table salt to a bucket of water and applied a small electrical current to disassociate the sodium chloride to produce "mixed oxidizers". They mentioned that you can use a solar panel, generator, or car battery to produce the required current.

The bucket of water becomes a stock solution that is then mixed in to untreated water. If I have some more time, I might be able to track this down further.

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi DHD
Thanks for the tip, I hadnt heard of that process.  But doesnt it further reinforce my point about simple expedients and why are these not commonly recommended.  I am really puzzled about that.Household bleach is readily available and cheap here, but the table salt and car battery is an even more basic idea (of course a car battery is not suitable for deep discharges, even a new one will rapidly deteriorate and lose capacity - been there done that). but the solar panel is a possibility, at a price. need to find out some engineering details like how much power to disinfect a litre , what proportions of salt to water say 3%, probably not critical.
They mostly collect rainwater from their roofs here. I am working on a tilting collection pipe that will automatically dump the first 5 mins of rainwater. Then the gutters need a steeper fall so as to wash out leaves. Simple but would reduce water contamination. Leave in rainwater jars dont do well with added chlorine.

RE: Basic disinfection of potable water in 3rd world

Brian

I guess that you are looking in the wrong places. There is a whole Appropriate Technology Industry out there where low cost appropriate water supply and treatment systems are discussed.

Try sites such as

http://www.researchinformation.co.uk/apte.php#vol29no1

http://www.lboro.ac.uk/departments/cv/wedc/specialist-activities/ws/water-supply.htm

http://www.itdg.org

You should find the contacts are very keen to exchange ideas with you.

brian
 

RE: Basic disinfection of potable water in 3rd world

So Bris said:
> I guess that you are looking in the wrong places

You might be right. It sounds like brianslater is actually looking for an improvised / field-expedient / survival / type of technology, rather than a village system that might build on some existing infrastructure (like power)

If I look at his problem from that perspective, iodine might be a better treatment chemical. Its residual persists a litte longer and it doesn't seem to be as effected by turbidity and organics (leaf litter, etc.).

US Army FM 3-05.70 (Chapter 6- water procurment)
http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/3-05.70/ch6.htm

US Center for Disease Control (CDC)- Article on water disinfection and containter handling in 3rd-world countries.
http://www.cdc.gov/safewater/pub/pub/mintz_e.htm

RE: Basic disinfection of potable water in 3rd world

Brian, Sounds like an old rainwater/cistern system. This system has been in use for thousands of years and are still used in some rural areas here in the States. As in any potable water system you'ree running up against the problem of attention to and a fastidiousness in regards to cleanliness and hygeine. Welcome to the Third World, I know places where the water supply doubles as the sanitary sewer and everyone wonders why Typhus, Cholera, & Dysentary run rampant. A little hygiene goes a long way. In this type of system, the cleanliness of the collection, transmission, and storage is of the outmost importance.

My grandfather had a system that utilised a manual preflush dump, Organic debris screening prior to the cistern (made out of window screens), and final pump out filtration utilizing flannel cloth and homemade powdered charcoal. In addition, the system was inspected and cleaned once a month. It worked just fine, and no one every got sick.

When it comes to water purification there are four process employed, location of a clean source, chemical treatment, filtration, heat. Under primiteve conditions, normally chemically treatment is out of the question. That leave filtration and heat. The heat method is highly recomended because it destroys bacterial organisms that cause the diseases mentioned above. Thats why every one recomennds boiling everything. If it can't be boiled, bring it to 180F and hold it there for 5 to 10 min..

Hope this helps.
saxon

RE: Basic disinfection of potable water in 3rd world

Hi Brianslater

if you like to dose household bleach, you'd better use bleaching powder (containing ~ 60 % available Cl2) that is sold in Thailand. i visited 3 waterworks in combodia, they ordered from Thailand. your problem is, it's sold in 40 or 50 Kg package. too much for your demand.
i heard about slow sand filter that one applied  for rainwater cistern in rural area too, but don't have details.  you may get idea.

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Bris
I checked out the first 3 links but these are largely self serving, the 4th one was a complet pdf doc on rainwater harvesting, looks very good, will read it in depth.

In my humble defence, I would say that my first port of call was the intermediate/alternative technology searches, but I found these largely frustrating. They were more concerned with  puffing themsleves rather than offering tangible info. Many of these UK university sites seem to be like that, always looking for research grants etc. Not much use to me where I am with my slow inet link.
So I stumbled on this site which I guess is largely patronised by engineering professionals rather than academics. In praise of this site, I got more mentoring in a few days that the several weeks I spent on these other searches.  My experiences with conversing with academics is not good and has not been productive.

rgds

brian

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi DHD

I really enjoyed the US army emergency water tract, very down to earth. just the kind of approach that is needed
The other CDC one I have to digest some
Thanks

brian

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Bimr

I fully accept that bleach is not meant for human consumption. However, the benefits of one drop per litre of household bleach may far outweigh these concerns.
So far in my searches I have not found any evidence that this tiny proportions (ca 2ppm of CL) are at all harmful.
Will study you suggested link on bleach purification, at first glance I have never seen a fresh bottle of bleach which has anything other than a pale straw colour, indicating minimal metal ion contamination, but my searches continue.

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Saxon
I agree there are some pretty nasty water supplies around - you should try Nigeria - where I was once posted.
I can picture the cistern arrangement, something simple and automatic will suffice. Cant rely on granny getting up and operating a dumper every time it starts to rain.
Its difficult enough to persuade people to keep their jar covered with a proper lid so as to stop mozzies breeding. A cap ful of bleach soon kills off any larva btw and leaves no taste.
I am curious about your hoemade powdered charcoal btw.  Is it effective? how do you stop it floating?
If it is to be activated charcoal as used in professional water filters, then dont you have to heat it up in a closed vessel to 500C?

Of course the standard advice given is to boil water. Well I can say from personal experience that this is a last resort and is unreliable - shock!!
No, not that the process doesnt kill bacteria, its that the people you instruct to boil water dont do it, or lie about it - Old Nigeria hand.
In Thailand, instructions to boil drinking water are not convenient for the average rural family. They normally only have one charcoal pot going and thats for cooking rice. Its not that they couldnt have another one, its just so difficult to persuade granny to change her ways after 90 years.
Water is stored in cement jars here, 5000 litres each, usually about 6 of them will suffice an extended family for a year. They are traditionally emptied and cleaned out at the end of the dry season. I queried why they had some sludge in some of them. This started my hunt for a simple
improvement.
My first reactions are that
a) a steep gutter flow with catchment pot for leaves
b) an auto dump of the first 5 mins of rain
c) a dose of bleach at the beginning of the rainy season
d) properly fitting lids
will produce a big improvement in water quality
 
Another part of the problem is that pure rain water has no mineral content. This can produce calcium and related deficiencies in children.  I havent seen any source of instant water hardening salts to create "spring water"

Any one any ideas?

I always remember some of the finest tap water I ever tasted was from the Holmenkollen Hotel in Oslo, Norway. It was cold, clear and sparkling, effervescent with an amazing taste. I asked the management and they told me quite modestly that it came from a mountain stream at the back of the hotel and was used as potable water.

rgds
brian

RE: Basic disinfection of potable water in 3rd world

brian

I have to agree that in many cases: "They were more concerned with  puffing themselves rather than offering tangible info". . But there are some good sources of appropriate technology. It is over 20 years since I worked on rural development and provision of basic services to refugee camps in Africa (mainly Sudan) so I am out of touch but I will chase some contacts.- I understand the frustrations of steam driven internet connections.- As for boiling - it is not a solution .

keep at it - best of luck brian

RE: Basic disinfection of potable water in 3rd world

brainslater, Adequate training and carry through is of vital importance, simply instructing and hoping that it is carried through is not enough. The amplification and indotrination in regards to boiling, can only be impressed on the mind when the alternatives are made real, tangible, and visible. Such that, contaminated water leads to sickness, sickness leads to death, period end of discussion. It's one of natures ways of maintaining the population carrying capacity of the land. Or in other terms, it's a form of wildlife management applied to humans.  It's hard hearted but that's the way it works. Since one meal is prepared daily, the boil function needs to be accomplished at this time. Boiling enough for the next days potable uses. As to the naysayers, if done religiously, it works.   

As for the powdered carbon, it was held between two layers of flannel in a wood frame.

saxon

RE: Basic disinfection of potable water in 3rd world

Saxon - Boiling is a reliable means of disinfection. but there are a 101 reasons why it is not a solution. If I understand what you are saying it is that once it is demonstrated that drinking contaminated water leads to sickness then to death then if they don't do it then that is natural selection. I won't get involved in the morals of the arguments just in the practicalities.

1) Many millions have always drunk contaminated water and many have lived into their 80's. The argument is not readily apparent and is often not accepted. The indoctrination process is not a one shot (period) but a long learning process.
 I have attended site visits in Pakistan and seen qualified engineers (some with Phd's) take river water in a bowl and blow the scum and floating debris to one side and drink out of the other. - The comment made to me was that we (westerners) are allergic to germs. How are you going to indoctrinate the uneducated masses when the educated elite fail to grasp the message?
2) Responsibility for collecting and storing water is generally that of the females. In many 3rd world societies we are faced with a gender problem. It is often impossible to get the message through to those that matter. (I have organised village training in Africa where the women - who nee to be the recipients of the training- have been obliged to sit at the back and face it the opposite direction).
3) Fuel for boiling is as often as scarce as or even scarcer than the water. Whether it is boiled with the preparation of the days meal or not it takes fuel.
4) Inevitably the water will not be boiled and disinfected it will be warmed and incubated.

I could go on and list the rest of the 101 points.

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Bris
I agree with your camp, Saxon,s armchair republican views wouldnt reap much success where I am or have been. The ones who suffer most are the young children. The adults have usually gained some tolerance to dirty water(though not always).

When I was in Ikeja, lagos at the Airport hotel, it boasted an olympic sized swimming pool. The water was the colour of brown soup. A co-worker, made so bold as to dive in but forgot to close his mouth (bit of a dipstick, actually). He came out with some incurable stomach bug unknown to medical science, he had permanent diarrhoea, after 3 mnths he had lost 25% body weight and had to be shipped home to the Hospital for tropical diseases. I dont know if he was ever cured. Perhaps he should have boiled the swiming pool first.

BTW the women here in Thailand are the boss. They are the ones who would turn up to a village meeting. The men wouldnt bother

RE: Basic disinfection of potable water in 3rd world

Gentlemen, As to the efficacy of the daily boil regimen, we managed to keep at least 3.5 million men healthy and alive in the jungles and atolls of the South, Central, North Pacific; and Southeast and Central Asia. I'll stand on its efficacy.

Hope this helps.
saxon  

RE: Basic disinfection of potable water in 3rd world

Not a topic I wish to prolong, but out of the 3.5 million military personnel one can guess that at any one time 20% were suffering with diarrhoea and were being treated with drugs not available to the local population.

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi guys
One man's meat is another man's poison
And funnily enough we were chatting away about local water quality just this evening, with the local highways and facilities man who is the cousin of my wife (called an oh boh toh in thai)
Its the children who suffer, not big poofy marines.
I have been discussing the concept of dosing the cement jars with household bleach. We generally dont have nasty bugs like giardia or that other nasty I cant remeber the name of just now - somthing to do with beavers?. We are a simple rural environment.
I find this whole topic strange. Having spent my working life building control systems for the petrochem industry - with all their codes and standards - it seem to me that the water industry is incredibly amateurish by comparison, and I dont mean the guys who build dams or design water supply systems.  Its just the concept of what is considered acceptable water.  I remember some years ago listening to a reader at my uni, telling me that the regulations of water quality were extremely lax and concerned mainly with victorian principles of keeping Ecoli to the minimum. Troops in India and all that. There were no regulations about Nitrates of heavy metals. I guess things have changed a bit, but I dont see anything about the dangers of children raised on rainwater - with no mineral content - for example.
Excuse me if I am being naive here, but it seems to me that potable water is an incredibly precious commodity that has become increasingly scarce particularly for children.
If the petroleum industry offered a similarly poor quality of motor spirit or lub oil, engines would fail, heads would role, but it takes several years for rickets to develop or worse and of course, water comes naturally.
When I go back to the UK, london, I have to wean myself on bottled spring water for a few days, as the tap water tastes foul, to me. I usually have a stomache upset as well.
Let me pose this question, Do you have a statement of the contents of your tap water in the states? We dont have one in the uk, all food has to be labelled scrupulously, but drinking water (and beer for that matter) does need such a label. This doesnt seem right to me.

Any comments









RE: Basic disinfection of potable water in 3rd world

brian, Try Army Amphibious. The Marines get stay on board ship where they have seawater stills, sleep in bunks, and get three cooked meals a day. ;) Here in the States the Fed/State EPA have set up standards. At last count there were fifty parameters on the list. They run the gamut from turbidity, color and odor to gross alpha and beta radioactivity.

saxon

RE: Basic disinfection of potable water in 3rd world

Hi all,

A couple comments to summarize:
1.  A solution starts with basic sanitation. You need to show the women the benefits of lifestyle changes like controlling human and animal waste, hand washing, soap, etc. Container and water disinfection isn't as effective when the living area and people are grossly contaminated. We don't normally think about things like dung on our feet - which quickly passes to hands and face.

2. One point of disagreement...
Quoting Saxon:
"...Gentlemen, As to the efficacy of the daily boil regimen, we managed to keep at least 3.5 million men healthy and alive in the jungles and atolls of the South, Central, North Pacific; and Southeast and Central Asia. I'll stand on its efficacy..."

Sorry, but the local National Guard unit went to Iraq with their potable water treatment plants. That equipent doesn't boil, and as far as I can tell from http://www.quartermaster.army.mil, none of the Army's currently stock-numbered purification equipment uses boiling. The personal and squad-level equiment currently issued is based on the MIOX process I mentioned earlier. Los Alamos National Lab, DARPA, and the Army funded the R&D.

FWIW - Most aide workers I know are agreed that boiling is not an environmentally sustainable option. Deforestation is happening fast enough just for cooking fuel.

Cheers!
Dave











RE: Basic disinfection of potable water in 3rd world

(OP)
Hi DHD
Very good points there. The Iraqi environment would be difficult with no power to run water treatment plants and to pump fresh water. No doubt, water storage would be a highly contentious issue open to poisoning from malicious sources.

I think we have a conscensus that boiling is very good but not always practicable in difficult situations. It also wont get rid of turbidity, mud etc, so you have to filter it anyway and it make a cup of tea taste awful.

I have heard of purification tablets supplied to very up market campers at very expensive prices (several $ just for a one litre bottle). There are also some very expensive protable filters. Not suitable for a 3rd world scenario. However, I havent come across, instant chlorine tablets (or an iodine equivalent. I guess swimming pool suppliers have these and must get them in bulk from some process plant. We dont have many swimming pools here, just ponds and rivers.

I have searched into what pool suppliers do, but its mostly snakeoil.

What we also need is a simple source of natural minerals to put calcium and other trace elemnets back into the rainwater harvest. The locals here grind up fish, land crabs and snails (all uncooked) to get their calcium supplement. Its an unhealthy practice amongst Laos people and would give a westerner severe diarrhoea. Large amounts of Salmonella are ingested. They seem to be relatively immune, but it involves  using excessive amounts of Chilli pepper which ultimately leads to gastric porblems.

FYI chilli has similar addictive properties to caffein (for westerners). My wife gets irritable if she hasn't had a plate of "som Tam" - a thai national dish of unripe pappaya, green mango, chilli and various salad items pounded together in a pestle and mortar. I have discouraged her from using Pla La (which is the ground up fermented land crabs etc - smells foul). The chilli serves to disinfect the raw ingredients, but you need a lot of it.  Traditionally, the Laos living in the north east of thailand, were very poor, dirt farmers with very limited firewood (converted to charcoal). Much of their cuisine has evolved around raw ingredients with little cooking (except for sticky rice)and copious amounts of chilli, far too hot for westerners to stomach, yet toddlers seem to be weaned on the stuff.
A whole family can exist on $2/day, though more typically the income is $4/day. For all that, they are nothing like as poor as the people in Cambodia where wages are half the thai average of $4/day for labour. Our local admin services are pretty good (schools, hospitals, police, main roads etc). They are almost non-existant in Cambodia.

So I appreciate the experiences that you guys have to share as you obviously have at some time been there, done that and got the tee shirt. As I noted before, I find the academics and self styled alternative (or is it intermediate - they cant seem to agree on that either) technologists too concerned with chasing conference junkets and government research funds to share real knowledge (not all, but benefit  wise surprisingly limited.)

RE: Basic disinfection of potable water in 3rd world

dhdoyle, So what happens when you get cut off from the support groups or you lose your equipment for whatever reason? ;)

brian, As for iodine and its derivatives, they aren't 100% effective against giardia or cryptosporidium. Your getting to the point that the only real solutions are the identification of a relatively clean source, filtration and boiling regimen in rather primitive conditions, solar stills can also be an effective solution, although the output is rather limited.

Hope this helps.
saxon

RE: Basic disinfection of potable water in 3rd world

brianslater
In response to your earlier comment and I quote

"Do you have a statement of the contents of your tap water in the states? We dont have one in the uk, all food has to be labelled scrupulously, but drinking water (and beer for that matter) does need such a label. This doesnt seem right to me."

We in the US do have a statement of content,  the EPA requires that all water utilities produce and distribute a consumer confidence report (CCR).  It is due out by June 30 of each year and covers the prior calendar year.  

quoted from the epa website
"While water systems are free to enhance their reports in any useful way, each report must provide consumers with the following fundamental information about their drinking water:
the lake, river, aquifer, or other source of the drinking water;
a brief summary of the susceptibility to contamination of the local drinking water source, based on the source water assessments that states are completing over the next five years;
how to get a copy of the water system's complete source water assessment;  
the level (or range of levels) of any contaminant found in local drinking water, as well as EPA's health-based standard (maximum contaminant level) for comparison;
the likely source of that contaminant in the local drinking water supply;
the potential health effects of any contaminant detected in violation of an EPA health standard, and an accounting of the system's actions to restore safe drinking water;  
the water system's compliance with other drinking water-related rules;
an educational statement for vulnerable populations about avoiding Cryptosporidium;
educational information on nitrate, arsenic, or lead in areas where these contaminants are detected above 50% of EPA's standard; and
phone numbers of additional sources of information, including the water system and EPA's Safe Drinking Water Hotline (800-426-4791). "

Depending upon utility size, list the types of publication, from a copy to every household and consumer via mail to posting on the utility's web site and local news paper.  

Hydrae
  

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Saxon & Hydrae
btw I thought Hydrae was a multi headed serpent from greek mythology, and also some low life pond dweller?? ;-}

Yes Saxon, I learnt very quickly in Nigeria always to have a back up plan , and a backup one for that, havbing nearly been totalled twice over there.  But I didn tknow the basics of emergency potable water. Lagos belly was rife and I had to resort to coca cola and a teaspoon of salt for my rehydration.
Happiness then was a dry fart on an outgoing plane.

H

thank you for you info on US regs. I rather felt that you would have something pretty draconian, but does it make the water taste good? When I was in Texas, Corpus, the good ole boys wouldnt let anything past their lips that fish had made love in. Buts thats Texas, yeehaa - bless them.

I hope we can see here from the spirited discourse that we all agree that water is a very important resource that has been taken for granted and largely overlooked in by the future planners.  I could tell you some watergate stories about the privatisation of the uk water authorities some 20 years ago but I might get terminated like the recent UK weapons expert.

As the legendary Mae West said, "If you want to water my melons, then hold your drink" {

RE: Basic disinfection of potable water in 3rd world

Brainslater

Does not a water system look like a multiheaded serpent, such that when you cut one head off (solve one problem) more grow in its place?  (some also have compared me to a low life pond dweller) LOL

Taste, odor and items that contribute to taste and odor are considered 'secondary' contaminates, which are in the list, but offically the operator does not have to do anything about them.    

As for your original solution 4 drop of bleach, some brands of bleach add other cleaning agents besides NaOCl to the product.

Hydrae

RE: Basic disinfection of potable water in 3rd world

I am probabaly late on the draw for this thread, but figured why not throw my hat in the ring.

Perhaps bleach is not recommended as the cure-all because it doesn't kill everything.  Some protozoa like Giardia and Cryptosporidium are resistent to chlorine.  You may have heard of an outbreak in the US about 10 years ago in Milwaukee's water system that the chlorine disinfection system did nbot kill.

Given that boiling is not an option, you can go with bleach with the proviso that you may not kill everything, but it is a step in the right direction.  To get the most bang for your bleach, filter first.  Solids are homes for those nasty critters and they can effectively hide from the disnefecting chemical inside solids.

Now I assume you cannot get everyone to go out and buy a $100 filter, but how about something like cheescloth or coffee filter type material...diatamaceous earth if you have it in that part of the world.  Filter first to remove as much of the fine solids, then add the bleach.  I would recommend this over adding to the concrete barrels directly where there may be solids which interfere with your disinfection.

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Mat
Thanks for your input, the advice on filtering is good. Sometimes the obvious is overlooked.
WE dont have diatomaceous earth here. Would you suggest using sand and crushed charcoal in a barrel as a filter?

I suggested using a small dose of household bleach in the water because its collected from rain falling on a house roof.
The water is normally crystal clear. You have to keep the leaves out and clean the gutters once a year. It is unlikely to be contaminated by animal fecal matter, but birds are an unknown factor.

I would like to be able to carry out some field tests on biological content, but dont know what to use?

Any ideas - microscope?

RE: Basic disinfection of potable water in 3rd world

Brianslater

Any of the many coliform tests used by water systems would be a very good indicator.  Coliforms will be present in biologically contaminated water.
The colilert method is simple, fill the bottle with sample, add packet, incubate for 24 hours at 35 deg C, look to see if the bottle is clear, no coliforms present, yellow, coliform present, flourescence under black light, fecal coliform present.  Cost, about $8 to $10 a test, special equipment, incubator  
For an attached number use the heterotropic plate count method. prepare sample and filter, flow water through filter, inclubate, count colonies of specific colors. need a bit more equipment, takes a little more time.
www.hach.com has all the equipment, or there may be local labs in the area.
Hydrae

RE: Basic disinfection of potable water in 3rd world

(OP)
hy hydrae

thanks for the tip, cant get any prices from this site as I have to become a registered user and give all kinds of personal info first. Can you imagine walking into your local store and being asked for such details before you can get to the counter. You would walk straight out again.  This is quite typical of many so called ecommerce web sites. Customer care is way down on their list of priorities (top of the list is your email id and credit card no. first before they will talk to you)

Will pursue the agar plates in other areas

thanks

RE: Basic disinfection of potable water in 3rd world

WITHOUT RE-STATING THE OBVIOUS NEED OF CLEANLINESS--and  not becoming over technical----There is absolutely nothing wrong with the use of sodium hypochlorie if it is not made from a byproduct (spent acid) that may contain heavy metals......In any case, all benefits of bleach far outweigh the odds of any potential harmful effect.... As to the concentration required... This would be highly vairable because there must be a "FREE" chlorine residual above the chlorine demand in contact with micro organisms for twenty (20)minutes.... The chlorine demand is created by the amount of chlorine that must be used to oxidize "ALL ORGANIC MATTER" in the water...This matter could be  from decaying trees,dead animals, or sewers,etc.,etc. A FREE CHLORINE RESIDUAL SHOULD BE REALIZED ONLY AFTER TWENTY (20) MINUTES OF CONTACT....FURTHERMORE, YOU DON't NEED A TEST KIT BECAUSE WHEN YOU CAN SMELL THE CHLORINE AFTER TWENTY MINUTES YOU HAVE ADDED ENOUGH AND- IF YOU HAVE ADDED TOO MUCH,- JUST HEAT THE WATER AND DRIVE THE CHLORINE OFF AS A GAS...Regards, Countryham  

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Countryman

thanks for your input, as you can see from the thread, my simple question has generated some very sound responses.  My orignial query was that, when I searched the "alternative technology" type sites I couldnt find an obvious reference to household bleach - which is very cheap and plentiful here. All the high minded academics said you must boil the water. They have obviously never strayed far from their stipendiary seats.
Boiling is not always a viable option.

here's the bottom line

Rain water here is harvested from roofs and stored in 5000 litre ferro-cement jars.

The gutters flow into a large funnel. A simple gauze across the top of the funnel keeps the leave out.  This is important because decaying vegetable matter produces potentially toxic by products when in contact with chlorine  
THMs trihalomethanes.

A fine gauze is needed over the top of the jar to keep out mozzies

A syphon hose weighted at one end to draw water from the bottom of the tank.

The tanks are cleans once a year during the dry season

I put one bottle 700ml of household 6% bleach in once a year at the beginning of the rainy season, once the tank is 3/4 full. Slight smell of chlorine which goes after 2 days

This should take care of nasties from bird droppings on the roof (very slight possibility of contamination)

Must make sure there are no jungle chickens  roosting on the roof. they produce copious droppings

The water comes out crystal clear and the only problem i now have to solve is a simple way to put natural minerals into the water (calcium in particular)

Any ideas here?  no-one has solved this one (like take 1kg of calcium bicarbonate and throw into the tank - wont do the trick, just produces Co2 and insolluble calcium carbonate)

RE: Basic disinfection of potable water in 3rd world

So Brianslater sez:
> The water comes out crystal clear and the only problem i now have to solve is a simple way to put natural
> minerals into the water (calcium in particular)

> Any ideas here?  no-one has solved this one (like take 1kg of calcium bicarbonate and throw into the tank
> - wont do the trick, just produces Co2 and insolluble calcium carbonate)

Brian,
I think you're trying a bit too hard here. Calcium carbonate isn't exactly insoluble under these circumstances. Considering the long retention time you have, you might get good results by simply adding cleaned, disinfected oyster shell. It should provide a fair quantity of calcium and magnesium and you can montitor with a simple hardness kit. Heck, crushed oystershell or coral makes an alternative mineral supplement.

The only concern I have is that it doesn't sound like you don't have access to an analytical lab to check for heavy metals. Lead can accumulate in shell and that news has caused a media backlash here about its use as a nutritional supplement. It might be OK in your neighborhood.

Cheers!
Dave

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Dave

Oyster shells, that sounds like an excellent idea.
We have out here (in the Moon river - 2nd largest in Thailand) a species of freshwater oyster, freely available. I have eaten these, they are a bit chewy, like snails or whelks. The shells can reach palm size. They could certainly be cleaned up and boiled, then pounded in a mortar. Will certainly give that a try.

You say Im trying too hard, but in fact, calcium deficiency is a problem here because everyone drinks rainwater and its not so clever for growing kids who get bone problems in some areas.  Hardened water would solve the problem. They cant always afford UHT milk and there is no natural chalk in the area (all laterite red earth, iron oxide mud and sand)
Strangely the poorer kids in the far northeast fare better than the central areas because they are Lao- Isaan. These people have developed a cuisine that uses almost no cooking fire. Its all raw vegetables, edible insects, snails and small land crabs. These are all put into a mortar and pounded to a pulp with lots of very hot chillies, green papaya, vinegar and some sugar and a foul smelling fermented fish sauce called Pla Lah.  A westerner trying such fare would likely

a) have his tongue burnt raw
b) get severe dysentary or salmonella.

however the locals are immune to it, even the kids and the crustaceans provide the mineral input

They've been living like this for centuries. they also raise dogs for culinary purposes, but dont eat lizards or snakes (fear of bad spirits).

Never a dull moment out here

Cheers

Brian

RE: Basic disinfection of potable water in 3rd world

So Brianslater sez:
> You say Im trying too hard, but in fact, calcium deficiency is a problem here because everyone drinks
> rainwater and its not so clever for growing kids who get bone problems in some areas.
> Hardened water would solve the problem.

OOps! I didn't mean that calcium deficiency wasn't worth the effort! I meant that I thought you didn't have to resort to inorganic chemistry (adding calcium bicarbonate) in order to do the job.

I understand the red earth - rain forest soil is generally low in nutrients due to leaching, right?

Cheers!
Dave

RE: Basic disinfection of potable water in 3rd world

If you want to filter, you could use sand with or without charcoal in a barrel or a capped pipe (8"-12" diameter).

I would think you could perforate the bottom of the barrel/pipe cap, add a 6"-9" pea gravel layer, 12"-18" sand layer, and 12" charcoal layer (optional).  The pea gravel would help keep the sand from falling through the perforations (make sure the perforations are smaller than the pea gravel).

Clean the sand/charcoal/pea gravel thoroughly and disinfect it and the barrel/pipe with bleach before you assemble the filter.

Don't know how much water you put through the unit; but, instead of backwashing like a water plant does, every so often you would need to disassemble it rewash and/or replace the media and reassemble it.  This along with the disinfection will help remove most of the viruses and cysts.

RE: Basic disinfection of potable water in 3rd world

Countryham says
" A FREE CHLORINE RESIDUAL SHOULD BE REALIZED ONLY AFTER TWENTY (20) MINUTES OF CONTACT....FURTHERMORE, YOU DON't NEED A TEST KIT BECAUSE WHEN YOU CAN SMELL THE CHLORINE AFTER TWENTY MINUTES YOU HAVE ADDED ENOUGH AND- IF YOU HAVE ADDED TOO MUCH,- JUST HEAT THE WATER AND DRIVE THE CHLORINE OFF AS A GAS...Regards, Countryham "

one problem with the above quote.  


Chlorine stinks the most when there is not enough in there.

The biological material contain ammonia,  when chlorine starts to work on ammonia but is not done yet, it smells the worst!  chlorine combines with the ammonia to form monochlormine (a passive slow acting disinfectant) then it forms dichoromine then trichoromine.  It is only when there is more than enough chlorine for the ammonia reactions that free chlorine is present, at that time the odor drasticly drops.
The chlorine that is combined with the ammonia in the form of dichloromine and trichloromine are not available for disinfection but that is the stuff that realy stinks.
The rule of thumb for operators of drinking water plants and swimming pools,  if it stinks of chlorine, then add more...


Hydrae
  

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Hydrae
Thanks for that titbit, most useful.  In fact its these custom and practice things that are the most valuable. I am not at all skilled in the arts of chemistry but that paradoxical smell is a good tip.  Of course the ammonia thing comes from human bodies I suspect (in swimming pools).  

Its unlikely to be present in rainwater collected from a clean roof.?

Would it be likely in well water unless the well water was contaminated from a cess pit?

I heard there was a rule of thumb for the separation of a well from a cess pit

ie  the well should be at least 20ft deep with a leak proof lining pipe. The pipe must only draw water from the bottom . No water should seep from the earth layers higher up around the pipe. No surface water should run into the well.

The well should be at least 10 meters away from any simple cess pit.

Do you agree with this?

Of course it varies according to the soil and whether there is un underground impermeable rock or clay, but here its mostly laterite, iron oxide mud and sand for a considerable depth. the water table is normally 3 meters down rising to 1 meter in the rainy season.

rgds

Brian

RE: Basic disinfection of potable water in 3rd world

Brianslater

Well water can contain ammonia, even wells that test coliform free, I am working with a water provider that started chlorinating their well water for other reasons and found out they have .15 mg/l of ammonia in the well water. So they are increasing the dose above the minimum target.

As for your rain water situation, any biologic (including leaves) that gets into the cistern can be a source of ammonia or other items (such as iron) that will combine with the chlorine and reduce the effectiveness of the disinfectant.  As long as the nets you mentioned earlier are in place that should keep it under control  

As for drilling shallow wells in areas of high and variable ground water levels, this is risky to find a clean source because the time the water has been underground would be very short.  

In US wells need to be at least 50 ft from sewer drain systems (drain fields or cess pits), increase that to 100 ft if the well serves the public.  

It sounds like the local solution of cisterns on rain gutters is the most reliable for the long term when maintainted.  Using sand filters and bleach on this stored water is also an excelent idea to add to the multibarrier approach.

low life pond dweller ;-}

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Semo
Our local pond water storage systems use a backwash sand filter.  
We can make simple sand filters quite readily as river sand is plentiful.  Now about charcoal?

I have conflicting info on the use of this.  Ive heard that using ordinary crushed lumpwood charcoal(ie not farbricated charcoal as used on BBQs)has no real effect.  It has to be activated.  This involves heating it in a closed vessel to around 500C drive drive off any oils and impurities. Its then available to act as a de-odouriser and taint remover.

Any comment here?

BTW
Ive also heard that these BBQ nuts are fabricated by compressing crushed charcoal with common cement (as a binder) and waste oil to help with lighting the fire. The waste oil bothers me as I believe it can hold high levels of Vanadium. I wouldnt want that on my Tee bone.

Any comment?

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Hydrae
What is your definition of a shallow well as opposed to a deep well?

The traditional way here is to use pre-cast concrete rings about 1 metre dia and to dig inside so that the ring gradually fall into the well hole. Very tiring, takes 3 man 3-4 days and its hazardous. the depth is 15 to 20 feet max

RE: Basic disinfection of potable water in 3rd world

I apologize if I am repeating what others have stated, but this post has had several responses and I haven't gone through them all in detail.

I would suggest you think in terms of the multi-barrier approach and deal with all aspects of water supply from collection, treatment, supply/delivery, and ongoing monitoring. Do whatever you can to ensure a clean source. Is there a way to "keep the birds away" from the rooftops? Can you have the roofs gutters cleaned out frequently enough to reduce the organic deposits? That would be a starting point. The cleaner the source, the easier  it will be to treat and end up with a safe water supply.

Bleach is used all of the time in small communities for disinfection of drinking water. I have designed some small systems in Canada that use it as the only source of disinfection. Be aware that the concentration of the bleach does change over time as it is stored (decreases) so you should be carefull if you are dosing it on a volume basis only. Also, chlorine beach and organics can be a bad thing and can lead to formation of THMs. Again, try to reduce the organics in the water before you add the bleach.

It is important that the water being fed to the piping network have free chlorine residual, otherwise you are facing the real possibility that by the time the water gets to the user it will be contaminated once again.

A low tech, lo-cost residual test kit sounds like a must to me. It will be easy to teach the local people on how to use it.

Keep at the good work.

Red

RE: Basic disinfection of potable water in 3rd world

Hi brianslater

I agree with hydrae on the chlorine smell means add more.  I don't know what testing equipment you can get; but, a simple color wheel type of chlorine test (anyone with a pool has one) will probably suffice.  You can get ones where you dip a litmus paper in the water and compare it to the chart (very simple and foolproof).

I also noted that your original post said you only disinfected once.  Like redgreen said I think that a residual needs to be maintained.  That means you would test on a regular basis and add bleach as needed to keep the chlorine level up (if water is constantly added and/or removed from the storage) or redisinfect the water prior to usage.  If everything is not disinfected (jars, caps, etc.) or they are touched prior to sealing, the water can become contaminated again.

As for the charcoal.  To the best of my knowledge, plain charcoal will provide some adsorption like activated charcoal does; but, the charcoal is activated to make the material more porous so that it adsorbs more.  I've not tried it; but, I think plain charcoal will have some effect; but, with a lot lower effect and shorter lifespan than activated.  As far as BBQ briquettes, I don't think I would use them.  I'm not sure how they are made; but, whenever I use them to grill, they smell like something is in them that I wouldn't want in my water.

I'm not sure you really need charcoal though if you have a clean water that does not contain odors or other volatiles.

On surface water treatment plants in the states, a CT time must be calculated to ensure adequate removal of Giardia cysts and viruses.  Sand filtration accounts for 99.68% removal of Giardia and 99% removal of cysts.  That does not meet the gov't requirements; but, disinfection with adequate contact time accounts for the remaining requirements.  That said, the filtration will provide as much or more removal than the disinfection and provide you with a safer water without a large cost.

RE: Basic disinfection of potable water in 3rd world

A deep well is deep enough so short term weather effects are not seen in the level of water in the well.
for safety there should be a least one impermable layer before the water bearing zone (such as clay).  If the soil is permable all the way down it is still just irregularaly filtered surface water.

Hydrae

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Hydrae
Yes I get the idea. A deep well is one that taps below an impermeable layer.  I dont think we have any soil like that here, just laterite

Hi Semo
Its interesting about charcoal and its effectiveness when unactivated. I might try some kind of test.  Of course swimming pool water has a much higher concentrtation of chlorine and you dont normally drink the stuff. Whether litmus paper or colour wheels are effective on 5ppm Cl in potable water is questionable. Do you have any rule of thumb for the amount of sand filtration required for a small system of say 10,000 gals per year

Hi Redgreen
We have developed quite an enthusiatic thread here, more to the question than meets the eye.
I cant keep wild birds away from roofs but they dont normally perch or roost on corrugated iron roofing

The gutter problem is interesting becuase these are often high up, 20 metres or more and therefore difficult to clean.  I am looking at a ground level design (yes put the gutters near ground level).  These can be constructed from galvanised sheeting (used as roofing hips) folded into a vee shape with a 30degree angle. They are mounted on trestles 1.5m high and feed into the standard cement storage jars. Roofs here are typically constructed with large overhanging eves at least 1 metre. Although we get heavy downpours the pitch angle of the roof is shallow around 20 degrees and the water pours off quite slowly sufficiently to be captured in the gutter troughs below.

They are easy to keep clean and a simple filter mesh at the end traps any leaves. The only problem is jungle chickens and stopping them perching on the troughs.  Im working on this
Of course the disadvantage is that it doesnt look very elegant but in a farmhouse situation, nothing does anyway.

Perhaps I could put a layer of sand in the trough?



RE: Basic disinfection of potable water in 3rd world

Wow lots of good ideas amd observations.
I think the basic thing in your situation is,"do what you can".
Filtration, if possible, is most important, many of those nasties love to live on the particles and removing the particles will remove many of them. Is it now save? No but safer!
Clorination via household bleach? If that's all you have use it. Is it possible you will form some THMs organo-metalic compounds etc? Yes but which is worse that or the water in its non disinfected state.
Can't be sure you are keeping adequate free residual chlorine? A little chlorine is better than none, the buggies may grow back, but at least you knocked some of them down for a while.
If you can mannage it it is always best to have perfectly safe drinking water by controlling all these parameters, but if not possible, then as I said, "do what you can". Any improvement is better than no improvement.

Edd

RE: Basic disinfection of potable water in 3rd world

The litmus paper just shows what the chlorine concentration is.  Ranges vary by individual manufacturers or kits; but, they usually go from 0 to 4 or 10 mg/l.  You are looking to have 1 mg/l residual after a 20-30 minute reaction time.

Your situation is kind of different than meeting standards on a large scale like we have to; but, the basics should be the same.  As far as filtration is concerned, most of the filtration occurs in the top 4 inches of media.  We typically use 12-inches of sand.  We also use 18-inches of antracite coal on top of this; but, the antracite is an optional layer that is primarily used to extend the filter life.  Older sand only filter designs used 24 to 30 inches of sand.  All of this is above the support media (larger sand/gravel which keeps the sand from washing through the discharge).  As water wizard said, anything is better than nothing.

Sand filters are also typically designed for a flow rate of approximately 2 gpm/sf of surface area.  I don't know how your water arrives.  You may have nothing then a sudden surge of water during a storm.  If that is the case, you may want a holding tank before the filter with a small opening in it acting as an orifice to keep the flow rate relatively constant.  You may have slow consistent storms which deliver water on a constant flow where you can size a filter for that delivery rate.  With this in mind, you can size the surface area of the filter for the flow rate that suits your system.

You will have to clean the filter media by washing it every so often.  A lot of that also has to do with your water quality and the sand size so making a statement on how often will just be a guess.  The dirtier the water, the more often you will have to wash it.  Also, the smaller the sand particles, the more quickly the particles get trapped and the more often you wash it; but, the larger the particles, the deeper the penetration of the dirt.  

Typically, as the filter media becomes dirty, the water level above the media will continue to rise until enough pressure is generated to cause breakthrough.  At this point, the filter no longer works.  We typically backwash on a daily or bi-daily basis unless 3-feet of head is reached above the normal water level; however, that is with the plant in operation from 12-24 hours each day.  We typically see filter run volumes of 1000-2000 gallons per square foot between runs.  

If your water is clean coming into the filter, I will guess that you will want to wash every few weeks.  You will have to watch the filter to see how it acts.  You also need to keep the filter media submerged to prevent it from drying and shrinking (forming voids for the water to run without filtration occurring).  If you see cracking in the media, media pulling away from the sides, or clogging (evidenced by high ridges in the sand), you've went past the backwash time.  If you're water is clean, you probably won't see this and will just need to set up a routine to backwash on a regular basis.

I hope this helps.

I also thought of something you mentioned in an earlier post about needing more calcium in the water.  I don't know what you have access to in your location; but, with bleach as a disinfectant, you are using Sodium Hypochlorite which is in a liquid form.  Swimming pool people typically use a white granular disinfectant which is Calcium Hypochlorite.  The use of it as a disinfectant will add some (be it small) calcium to the water.  There are some disinfection systems here that use this chemical (in pressed tablets) where the water flows through it and over a specific number of tablets to get the chlorine concentration needed.  If you had access, you could place these tablets in the flow to constantly disinfect the water as it flowed through the filter into your holding tank.  Just a thought.

RE: Basic disinfection of potable water in 3rd world

(OP)
Hi Semo

Thanks for the tips there , will "digest" the filter info. Water is something we all take for granted. I wish some 15 years ago I had migrated into the water industry along with many others who came across from the Petrochem industry (when it went through a drastic price crash). There is something rather satisfying about producing a clean water supply not like petrochem products where I got stuck.

FYI  the main differences between the industries are

a) 5 year project timeframe (instead of 9-18 months of frantic pressure
b) Non hazardous process (instead of an often highly dangerous environment)
c) stable market (instead of the resource often being controlled in a politically volatile country)

 

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