Corrosion of homes' copper water lines

If it is the cold water lines it is do to too much acid flux being left in the lines by the plumbers.

This seems to rule out electrical causes...

Have you looked at the Ph of the soils? They may be in a corrosive soil or acidic soil. Have the lines been removed and replaced? Can you get your hands on them? May be the wrong grade of pipe or a bad batch of pipe from the factory. Also check the Ph of the supplied water. don't rely on the Water Utility to give you the correct answer. Look at what is happening in Wash. D.C. and that water Utility. Their problem is aggressive water and lead levels.

The obvious thing to do is to put a clamp-meter around the earth bonding wires and see how much current is flowing into the water pipes. The fact that there is no voltage difference between earth and neutral means the cross-bonding is working. It is the current level that tells you something interesting.

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

Copper pipe sometimes has a carbon film inside due to manufacturing problems; this film often results in premature corrosion.

Regards,

Brian

Maybe GOTWW has the answer. Just two homes out of how many? Same plumber at both sites? And did he(she) work at more than these two places?

These are the main outside lines (therefore 'cold') entering the homes. They are connected with compression fittings, so I do not think flux is the issue here.

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.

If the 'source pipe' has these compression fittings, thepipe may be isolated by the gasket in the fittings. May want to check current in the 'source' pipe.

I have encountered 2 related problems and there are 2 theoretical problems:

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

this doe snot appear to be electrically induced corrosion.

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?

Seems I read something on Mike Holts web page about such a problem. This was about 6-9 months ago. Probably in a newsletter or a reader needing help. May want to look there.

You could also have some bad copper tubing. Most copper tubing is made by roll forming copper sheet and then and induction welder is used to weld the seam under roll forming pressure. Copper can be very difficult to weld and all other things being equal needs 6 times as many watts of BTU per to weld than steel. Therefore, there is more opportunity for quality control problems when making copper tubing.

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.

Was the corroded portion of the pipe underground? If yes, are there any cathodically protected under ground gas lines in the neighbourhood?

Sarg

See
for relevant information on copper pin-hole leaks.

The enclose site may have information related with corrosion in copper water lines. See if this could help

TINFOIL: The casuue could be one of the many mentioned or a combination. If it is inside the hot water lines, there is a possibility it could be erosion-corrosion. Erosion-corrosion can be caused by many things individuallly or together

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 or do a web search on erosion-corrosion

Regards
Dave Hall

Since you have corrosion and leaks, you have to replace the pipe. Gently remove the defective pipe and send one piece to a met lab and have them to a failure analysis on the metal. Send another piece to a chemical lab and define exactly what corrosion is present. Send a soil sample to a lab to determine the exact soil conditions. Send a water sample to a lab and define all of the water properties.

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.

I'm surprised to hear that the municipal water authority is using copper pipe for its underground service. Is this common? I would have expected iron pipe to be preferred.

Most water services for single family houses that were installed since 1950 here is the U.S. are type K copper tubing. The reasons for using it are:

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.