Domestic water tank and system setup.

[itsmoked]

I have a customer who I just found out has a concrete water tank that is elevated about 300ft above the well and that's about 150 ft above the mid-point house. The horizontal distance all this is spread over is about... 1000ft.

From the house up to the tank is 4 inch. The tank is currently not in use as the valve to the tank is closed and the pristine tank is dry as a bone and has never been used.

There is/are no pressure tank(s) involved anywhere in the system. I believe the top part up near the tank of the 4 inch fire main is filled with air and is an ad-hock pressure tank because the well doesn't seem to be short cycling. I'm sort of amazed by this because I'd really expect the entrained air to dissolve into the water eventually, water-logging the ad-hock bladderless air tank. Not happening.

What is the commissioning procedure for a new tank like this? No one uses chlorine in their tanks or systems in the area. There are 3 ten thousand gallon tanks for other houses on the same plot and none are chlorinated. Should one at least chlorinate the first fill? 1ppm?

My biggest concern is if the tank is filled via the fire main, from the well, up the hill, I could see filling the tank then in normal use the water in the tank just going up and down but never actually ever turning over since a 4 inch line that's five hundred feet long has way more water in it then the house would ever normally use. I can see the well water turning over in the lower section of the 4" but never actually turning over the water in the upper section and of course never the tank water. Is this a justified concern?


Keith Cress
kcress -

http://www.flaminsystems.com

 

[ashtree]

Keith,
A sketch would be good.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[itsmoked]

OK. I'm a sketch person myself. Late night, here's my hack at a MS paint sketch.

Green is land.
H = hydrant
System is currently run with only a pressure switch. That would be changed to a float switch in the tank.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ashtree]

It looks like the intent is to basically use the tank as a header tank for "fire flow" a water reserve and to fix a minimum pressure for the system.
I am guessing though that the well pump normally supplies the house on demand via the pressure switch.
It is definitely different.

Its hard to advise on the need to chlorinate. I would suggest that if there is even a hint of contamination in the tank and the water is to be used for potable type use then it should be chlorinated. The well water itself may need to be chlorinated as well even just for normal use, but its difficult to advise without knowing a lot more detail. Just because other wells in the area are not chlorinated does not mean they should or shouldn't be. It depends on the type of aquifer, depth , well construction , land use etc.

The water going up and down the pipe need not be an issue if the system is sealed so there can be no contamination.

There are lots of unknowns here though.
I think your concerns are valid to the point that it should be investigated a little more.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[Valvecrazy]

With the valve at the upper storage tank closed, that is a sealed system and should not need chlorine if the well water is clean to start with. I don't think you will lose air, as the water does not flow past the air to grab it like it does in a hydro-pneumatic tank. As a matter of fact I think air will accumulate in the upper pipe the same as it does in high spots in irrigation lines. You need 65 PSI just to get water to the house. That would mean a pressure switch setting of 105/125 to get 40/60 in the house.

 

[bimr]

There are all sorts of concern.

In the initial commissioning, the tank system should be over chlorinated and flushed. How would anyone consider any other recommendation? Any competent professional water treatment person would concur.

Tank

I suspect that the well has low capacity and that the tank is equalizing the well water flow over 24 hours.

The oversized storage tank and 4-Inch water main will be the cause of stale water. For this reason, most municipalities cycle their storage tanks and flush dead end water mains.

Continuous chlorination of some kind is recommended as there is no way around it. Recommend a carbon filter be installed where the water enters the residence. Carbon will remove the chlorine and improve the quality (taste and odor) of the water.

Chlorination Link

Notwithstanding what the neighbors are doing, this installation will be at risk of stale water, legionella, giardia, whatever. If this your customer, you would not want to be responsible for things that are out of your control.

 

[Valvecrazy]

Because the valve to the upper storage tank is closed, the storage tank is not in play. The well and piping should be sanitized after any repair or after opening the well. But perfectly clean well water in a closed system should not need regular chlorination. You would be adding toxic chlorine to a pristine water supply.

 

[bimr]

But perfectly clean well water in a closed system should not need regular chlorination. You would be adding toxic chlorine to a pristine water supply.

How about giving a reference source that states no drinking water disinfection is necessary. Is "perfectly clean" a scientific term? My understanding is that millions of people in the U.S. are sickened annually from the lack of proper drinking water disinfection.

 

[stevenal]

Valvecrazy,

OP wishes to open the upper valve so stored stale water can feed the hydrants.

Suggest: Keep pressure switch, install pressure tank at house, and install back flow preventor just before the transition to 4". Stored stale water can then feed the hydrants without getting into the domestic water. Of course that is a disadvantage as well: no storage of domestic water for dry spells.

 

[77JQX]

Just a note that 500 feet of 4-inch main contains about 300 gallons. Usage for my my two-person household ranges from 100 gallons per day in winter to 600 gallons per day during irrigation season. Depending on the usage at this house, you may actually be able to get cycling of the tank.

Otherwise, I concur with bimr's recommendations.

 

[itsmoked]

Thanks everyone for your excellent points. This system was designed by a zany engineer who over designed and massively over tricked-out everything he did at the 15 acre site.

Take a look at the plumbing up at the tank:

Notice the two 1" lines arriving from the left with the aforementioned 4" line? One could hope. :/

I believe the 4" lines have one exiting the bottom of the tank and one entering up several feet from the bottom.
There is also a drain line out of the center bottom.
There is also an overflow line.
That explains the two 4" and two 1-1/2" but it leaves about 5 more entering the tank...

It could well be there is a line directly from the well to the tank, no one is sure as the guy passed away moments before commissioning this thing. I'm hoping one of those 1" lines seen in the tank-pit are coming from the well. This, of course, would solve the stagnate tank issue nicely.

Here's the plumbing at the well head:

For instance note the multi-use aspect of this 'controls' conduit. Don't get me started on the three mystery buttons either.

What do you think that information is? Maybe low water level and ...?


Keith Cress
kcress -

http://www.flaminsystems.com

 

[Valvecrazy]

“Although the U.S. has one of the safest drinking water systems in the world, there are an estimated 4-32 million cases of acute gastrointestinal illness (AGI) per year from PUBLIC DRINKING WATER SYSTEMS.”

https://www.cdc.gov/healthywater/burden/index.html

I know there are a lot of wells that need water treatment, but when they don’t, they don’t. “Pristine compared to city water” was the way the lab tech described the test on my well water. I am lucky, I know. But I have not chlorinated my well in 16 years, which was the last time I pulled it out to work on it. There are a lot of water wells that do not need treatment of any kind unless you open them up to work on something.

I am more afraid of public drinking water systems having miles of lines, storage tanks, and transients causing negative pressure waves than I am of an individual water well supply.

If you leave the valve at the top of the hill closed (don’t use the storage tank), the 4” line will act like a pressure tank. If 500’ of 4” main will hold 300 gallons of water, it will have a drawdown of about 50-70 gallons if the air ratio is pretty close to correct. Running the pump with a pressure switch at the bottom of the hill would require a 105/125 pressure switch setting to get 40/60 at the house.

If you open the valve at the top of the hill you will need a pressure switch setting at the well of about 135/155 to get the tank on the hill to fill up. Then you will need a float valve at the storage tank to keep it from over filling. The double check above the house would not let contaminated water from the storage tank enter the house. Probably also need a pressure reducing valve going into the house as the pressure will be 70/90 or so. And of course you will them need a pressure tank capable of 135/155 as the pipe will no longer work as a pressure tank.

 

[bimr]

Most of the 43 million Americans who rely on private wells don’t know if their water is safe to drink or not because people never bother to test their wells.

The responsibility lies with owners, many of whom never test their wells because of cost, disinterest and a lack of knowledge. Yet their wells could be contaminated by substances such as arsenic or uranium from bedrock, nitrate and manure runoff from farming, or human waste from septic systems.

A study in 1999 for the USGS found that 23% of the surveyed private wells were contaminated. That equates to 10 million private wells that are contaminated.

At a minimum, an annual well maintenance check, including a bacterial test, is recommended.

 

[Valvecrazy]

I still trust my private water well more than a public water system. I don’t see people dying from Legionnaires Disease or having pipe scale and lead ripped out of the system by someone not treating the water correctly, as has happened too often in public water systems.

 

[LittleInch]

What are the current start/ stop pressures set at? If the now departed engineer set this up for operation with the tank, they could already be higher than what the house actually need so its own, but tif they've got used to having decent pressure than that's Ok.

Given the very small surface area to air volume I'm not surprised that the ad hoc pressure tank is working OK and if that water is essentially static in the pipe and just goes up and down, the air content is saturated already.

I can't comment on the chlorination aspect, but potentially using stale water exposed to air and unknown bugs doesn't sound like a great idea to me.

If you put NRVs immeadiately upstream the house and fill the tank once then ok, but then you loose the pressure cycling impact.

If it ain't broke don't fix it is my motto here providing the pump can supply the hydrants with enough water.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[hydrae]

Back to the original question.

Is there a float switch at the tank along with the needed wiring?, if not, then setting pressure switch to control the pump to keep the tank in operation will be very difficult. My guess this is the reason why the tank is not in use. In order to use this tank, tank level information needs to get to the well control as setting a pressure switch to cycle on at 135 psi but off at 136 psi is tricky at best. Since the original builder is not in the picture, a well driller was called to complete the system and they will install what then know. put in a pressure switch and see how it goes.

My advice, install the float switch, disinfect according to the instruction outlined by Bimr, flush and refill the system until no chlorine is detected and then sample for coliforms.
Keep that well pit clean and inspect the vents on the tank on a regular basis along with annual testing for coliforms

Hydrae

 

[bimr]

The problem with that line of argument is that it is powerless without sound evidence or information to back it up.

 

[77JQX]

If water scarcity isn't a problem, the well could be set up on a timer to run x hours per day and simply overflow the tank when it's full. That would solve the control problem and water freshness problem.