Corrosion of homes' copper water lines
Corrosion of homes' copper water lines
(OP)
I work for a electric utility.
We have just had at least 2 occurances of severe corrosion and pinholes in copper water lines supplying residential homes in a rural subdivision that is less thna two years old.
There is a local central water system using PVC pipes for their mains, and copper lateral lines to the houses. Building codes require electrical system bonding to the home's copper plumbing systems.
We have been asked by the Municipal Water Dept if this corrosion could be 'our fault'.
We have checked our system out. The padmounted transformers are properly grounded. The neutrals of all underground cables seem intact and are bonded at each transformer. There is virtually no voltage difference between neutral and ground at each affected home's meter base.
Anybody have any insight here? I am prepared to tell the water guys that we probably aren't the cause, but thought I'd get your opinions on this.
We have just had at least 2 occurances of severe corrosion and pinholes in copper water lines supplying residential homes in a rural subdivision that is less thna two years old.
There is a local central water system using PVC pipes for their mains, and copper lateral lines to the houses. Building codes require electrical system bonding to the home's copper plumbing systems.
We have been asked by the Municipal Water Dept if this corrosion could be 'our fault'.
We have checked our system out. The padmounted transformers are properly grounded. The neutrals of all underground cables seem intact and are bonded at each transformer. There is virtually no voltage difference between neutral and ground at each affected home's meter base.
Anybody have any insight here? I am prepared to tell the water guys that we probably aren't the cause, but thought I'd get your opinions on this.






RE: Corrosion of homes' copper water lines
RE: Corrosion of homes' copper water lines
http://www.corrosionsource.com/discuss2/ubb/Forum4...
RE: Corrosion of homes' copper water lines
RE: Corrosion of homes' copper water lines
In the factory where I used to work (in the UK) the earth currents were in the region of amps. The supply company inspected their system and couldn’t understand it, but none of us were prepared to dig the road up to find out if a neutral bond had fallen off somewhere
RE: Corrosion of homes' copper water lines
Regards,
Brian
RE: Corrosion of homes' copper water lines
RE: Corrosion of homes' copper water lines
At the time we were there, a clamp-on ammeter showed no detectable levels of current on the two water lines.
Curiously, the heavily-corroded part of the pipes was on the 'source' side of the water cut-off valves (all installed by the developer's contractor), which was backfilled by crushed stone, whereas the portions of the pipe on the consumer side of the valves, installed by the homeowners' contractors, were installed in native soil backfill and were not particularly corroded.
We are up to three bad pipes now. They all happen to be served by the same transfomer. We have checked out the connections throughout this unit, and even exposed tops of the ground rods and 'ground loop' to ensure they were intact.
RE: Corrosion of homes' copper water lines
RE: Corrosion of homes' copper water lines
1. Some of the well waters around here (in Northeast Ohio) have bacterially generated sulfuric acid which corrodes copper water pipes over time. These is an article in Scientific American about how sulfuric acid generating bacteria are used to leach copper out of low grade copper ores. Most species are aerobic and could be corroding the copper water pipes from the outside. I also wrote my term paper for freshman english in metal corrosion bacteria. In these situations submersible well pumps need to be Grundfos stainless steel pumps.
2. I have encountered an instance where properly grounded plumbing and appliances had tingle voltages on them. The cause was a failed underground 120 volt power line that was leaking 7 amps during a drought! I had to bond the hot water, cold water, and drain pipes to the grounding electrode conductor to get rid of the tingle voltage in the bathroom. The mechanism was that current flow through the soil was energizing the drain pipes and basement floor.
I had a hard time finding the source of the problem until the tenant told me that he had $200 to $500 per month electric bills even though the space and water heating was natural gas. I then proceeded to run the same tests that Cleveland Electric Illuminating runs when a customer has an electric bill that is too high. Sometimes they find someone who has 500 or 1,000 watts leaking out of their knob and tube wiring and into their woodwork like they do not need to install electic baseboard heat.
3. Something could be leaking direct current into the alternating current system. Most of the gas and oil pipelines have electrolytic corrosion protection and if the bus that supplies the carbon anodes is not properly isolated the DC could be getting into the electrical grounds.
4. There could be something wrong with ground rods but usually it would be steel that is corroding by electrolysis.
You need to get an AC/DC clamp on ammeter. This uses a hall effect chip or a 3 winding saturable transformer to measure DC.
Mike Cole, mc5w@earthlink.net
RE: Corrosion of homes' copper water lines
the use of crushed stone for use as a back fill for copper pipe between the mains and your shutoff valve is a concern. what sort of crushed stone is used, how is it tamped... also are the "pinhole leaks" internal pinholes as might be due to MIC or external as due to physical damage?
RE: Corrosion of homes' copper water lines
RE: Corrosion of homes' copper water lines
I also bought some CPVC pipe that split when I turned on the water pressure. The problem was that the extrusion parameter were not right and as a result the pipe was not seamless.
I returned the pipe and fittings and got my money back. I went to a different supply house and bought a different make of CPVC pipe that worked fine.
When plastic pipe is extruded there is a support for the inner part of the die. If the extrusion parameters are not set right the pipe will NOT be seamless and will split when pressurized.
Hacksaws suggestion as to fill might be correct. If somebody used cinder fill or sharp rocks you could have a problem.
In a related issue, Summit County, Ohio has banned direct burial electrical services because there have been too many instances of the Rock Circuit Breaker Method and the Tree Root Circuit Breakers Method.
RE: Corrosion of homes' copper water lines
Sarg
RE: Corrosion of homes' copper water lines
for relevant information on copper pin-hole leaks.
RE: Corrosion of homes' copper water lines
http://www.ccbda.org/publications/pub28E/28e-secti...
RE: Corrosion of homes' copper water lines
hot water
hard water (greater than 100 ppm ca+)
water velcoity over 5 ft/min
soldering flux in the lines not flushed ut
poor soldering
discontinuiuties in the line
others
Check www.nace.org
or do a web search on erosion-corrosion
Regards
Dave Hall
RE: Corrosion of homes' copper water lines
You have a massive legal liability exposure so I would spare no cost in defining the problem because somebody is going to be responsible for the entire sub-division's problem. This could be a huge financial cost for whoever ends up being resposible.
RE: Corrosion of homes' copper water lines
RE: Corrosion of homes' copper water lines
1. Does not get clogged with iron bacteria.
2. Does not get clogged with water hardness scale.
3. Does not corrode on the outside under MOST circumstances.
4. Provides a superior electrical ground versus ground rods.
5. Can be connected using soldered or brazed fittings.
6. Can be connected with solderless flare or compression fittings. Usual practice is to use flared fittings on residential services.
Some multifamily dwellings also use copper tubing water service(s). 4 inch and larger water services are usually steel pipe and sometimes plastic pipe.
Plastic pipe has also become popular in some areas but the are some water departments that still require metal pipe because of the electrical grounding issue.
Services for fire sprinkler systems are almost always in steel pipe.
RE: Corrosion of homes' copper water lines
If it's inside to out the electric utility is probably in the clear.
The other aspect is pipe to soil potential. This is a measure of the half-cell difference with respect to a known reference. The usual half cell is Copper/Copper-sulphate and copper that is not being forced is about zero with respect to a Cu/C-S half cell