Copper corrosion and blue water in residential water system

A. I have seen on the internet Oscillating Rings that take care of rust, lime scale, bio film and various other problems in the water system. I am sure these are an answer to your problems. I have one in my house and it has cleaned all the pipes of calcium build up, including the recurring problems in my showers holes that got clogged regularly.

August 6, 2008 Please note that it was a reader, not the site's editor, who recommended these "Oscillating Rings". I'm not familiar with them but the explanation on their web page struck me as awfully silly. Just my opinion. Regards, Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey

A. After finding some copper flakes (!) coming out of our bathtub faucet, my wife (with knowledge in metallurgy) suggested we needed to do something, so I read up on corrosion enough to understand there were many possibilities. Also, reading this thread it's striking how very complex the combination of possible factors is for each house. I count 6 possible factors to consider in deciding what to do: ordinary galvanic corrosion (this is common), electrically driven corrosion, pH driven corrosion, oxygen driven corrosion, considerations of grounding pipes (advantages vs disadvantages), and of course the effects of changes in standards of water supply by cities and in grounding, all contributing to possible complex situations.

Consider for instance that even copper tubes are thought to have some impurities that could lead to local galvanic corrosion.

I wonder if using a "sacrificial anode" (a standard part of every water heater) might help in many instances …

For example, your hot water heater anode may be worn out, contributing to increased corrosion not only in the water heater itself, but elsewhere also. One possibility.

Many water heater anodes can be easily replaced, and it's worth a look for a do-it-yourselver that takes simple precautions such as turning off the water at the outside meter after having turned off the water heater and run the hot water out of it, etc. etc.

A. I have found many of the comments of great value and there are many good insights. I have done some recent research on this subject and would like to share my 2 cents worth. My initial question of anyone calling with blue/green staining is, "are they noticing staining connected with both the hot and cold water". If the problem seems more prevalent on the hot side, I have suggested checking the temperature on the hot water heater. If it is above 120 °Fahrenheit, I suggest that the temperature be reduced to that level. Also with the square footage of homes increasing many homes are equipped with a recirculation loop to provide instant hot water at every hot water location. These systems can contribute to erosion corrosion is some situations and reducing the pumps velocity or turning them off altogether has eliminated the problem.

High levels of Dissolved Oxygen and Carbon Dioxide are other issues that can cause copper corrosion and should be checked. I will not go into electrical cells that are set up in the plumbing because that has been covered in this thread by folks more knowledgeable than myself.

I would just like to mention that in some cases, we have used poly phosphate feed to form a coating on pipes to protect them from corrosion. This naturally occurs when the copper is exposed to hard water but where water softeners are installed on new plumbing or the water is naturally low in total dissolved solids and hardness using poly phosphate can be an option.

Lastly, it is important to realize that once corrosion begins it can be very difficult to stop. With in the corrosion pocket a mini environment is established which can be much more corrosive than the surrounding water. In these situations encouraging the copper piping to establish a protective coating may be the only solution.

A. The problem of corrosion and pin hole on the water pipe caused by the water pipe being used as the neutral-to-ground bonding jumper in the electrical panel in your house. You have not electrical ground in your main service per NEC250.

A. An entire housing tract in Danville, California had or has this same problem. Bill Watenburg, electrical/mechanical engineering professor at UC Berkeley and radio host, suggested a fix by providing a constant source DC voltage power supply, presumably low voltage, applied between the copper pipes and earth ground. Power supply voltage and connection points were a variable depending on measured results. I don't recall all the particulars. However, the "blue water" situation seems to have stopped shortly thereafter.

A. I recommend that for a complete explanation of all of the above problems you search on: "stop-pinhole-leaks" and read the information. This is NOT a recommendation of the company but the theory is good and has been used for lots of years in the petroleum industry protecting tanks and lines. That information should end your speculation.

A. I stumbled on to your site looking for something else but I'll throw in my two cents. I'm an electrician. I was working for a Country Club and members complained of "tingling" sensation while showering. Sure enough there was about 5 volts AC on the plumbing lines to Earth. I checked all grounding and found nothing wrong. We tried turning off different circuits with no luck and finally shut down the entire building. The voltage was still there. We thought it might be coming from the phone lines or cable and eliminated those sources and the voltage was still there. I called the power company and they sent out a tech. I duplicated what I did with him and he was as baffled as I was. A few days later the power company sent out an engineer and he told me he had seen this before. He called out some linemen to check the connections on several transformers in the area (mounted on the ground with underground services - not on poles). He found one about 250 yards from the building with a bad neutral connection. They corrected it and problem solved. No more stray voltage and no more tingling. Who would have thought a transformer a couple hundred yards away could induce stray voltage into the copper plumbing lines because of a bad neutral connection?

A. Plumbers and electricians often confuse or call Galvanic Corrosion "Electrolysis". Any internal corrosion of a pipe will not be caused by stray currents occurring on the exterior of a pipe. Blue water is a water chemistry issue. Remove your water softeners so that your copper piping can oxidize and develop its patina and a nice shield of calcium carbonate. Using pre-oxidized pipes, not a bad idea. External corrosion of your copper pipes may be due to SOIL CORROSIVITY or because a HOT water pipe is in close proximity to a COLD water pipe. Copper is susceptible to thermo-galvanic corrosion. ammonia [on eBay or Amazon] and nitrates are also bad for copper so if your copper piping is in soil, you should have your soil tested.

A. Wow, lots of issues with copper piping, nary one answer for all, and some are close but none more informative than the copperinstitute.org. I've been plumbing for 30 years, and have seen, heard and read a significant amount of information about this subject. I'm a plumbing contractor, IAPMO, ICC plumbing inspector, and a certified Cross connection specialist (water contamination specialist). First things first, any change in the color of your water is considered turbidity, which could be caused from organic and inorganic dissolved solids. To be safe, I would have the piping system professionally cleaned as specified in the Uniform Plumbing Code with a mixture of sodium bicarbonate, this will neutralize any acidic issues, and give you a fresh start. Second, the ph of the water is essential to a healthy copper plumbing system, therefore a municipal water system should be used, not well water. Third some copper piping was found to contain steel coming from Mexico, which will cause in holes. Fourth, copper piping will expand and contract with temperature, and if uninsulated will rub on rocks, etc. and cause pin holes. Fifth, Soft underground copper tubing may be deformed or pinched during initial installation which may cause water velocities to wear at the deformed areas of piping causing leaks. Sixth, Non water soluble flux, or acidic flux (now banned) may also cause corrosion, as most fluxes were heat activated, this also may affect hot water lines. Seventh, Dissimilar metals, will also cause corrosion, as will acidic pipe dope compounds. Eight, Soil composition, is also an issue and is referred to as "Hot Soil", and may have a ph issue, or is high in salinity. Nine, any electrical current found in a copper piping system is of great concern, as this is the most under reported cause of death of plumbers who work on water systems, and is NEVER OKAY, the water pipe should have at least 5' of direct burial water main giving the system a proper ground, and should never be dependent upon a grounding rod that may not extend 9' down, or is only tied to the rebar in the foundation. Tenth, there are chemical treatments available for caustic water, and you should contact your county health department for the appropriate approved treatment should you need it. Pex is very durable, and has been around europe for some time. The fittings are not copper or brass, and should provide years of trouble free service for anyone with well water or issues unresolved concerning a dependable and potable water supply.

A. Moved into a house that is 6 years old and water on mains fine. However after switching to tank water (tanks a couple of years old) we have the blue residue. Have been told possibly the pH of the tank water is affecting the copper piping. Don't yet know the solution but will update this if we find one. Meanwhile I am switching back to mains water.

A. I run a small water testing laboratory and have been involved in many such cases over the last 15 years.
I see 3 different types of corrosion.
1. The water is aggressive (low pH,iron, nitrate present or calcium and magnesium absent i.e., soft water). Hard water is often not the cause of corrosion as it tends to leave a protective calcium coating on the inside of the pipe. It does leave a deposit in the jug.
2. There is a mixture of metals in the plumbing system. typically iron, zinc (from galvanizing) and copper.Recently I have been involved with a coastal location with under floor aluminium foil which was in contacted with the copper plumbing. In this case the problem was only measurable during an easterly storm when the sea spray aluminium insulation and iron nails were creating a battery cell.
This type of corrosion is galvanic and generates a DC current. This can be measured. Reverse polarity of probes reading should also change polarity. If it doesn't, then there could be and AC component to the current leakage.
3. An electrical device, this includes the power meter, maybe leaking a small amount of AC into the electrical system. Dishwashers, water pumps, waste masters,washing machines etc, can all be responsible. Modern devices often have switch mode power supplies which can leak current. Unplugging items from the electric sockets.
Checking for electrical leakage is not easy and requires methodical recording of MV readings as you go through the plumbing system.
I usually start with a water test. Two sample are collected first thing in the morning (before toilets are flushed and showers are used). Run the tap in the area showing blue or green staining wait till hot water comes through from cylinder and collect 50 ml. Run the cold till for a few seconds and collect a sample. The hot sample represents what has come from the hot water cylinder. The cold sample represents what is in the cold plumbing.
Because chemical reaction occur faster at higher temps (generalisation) The hot sample will be higher in copper than the low sample if it is a chemically aggressive water.
If the cold side has a higher copper content than the hot then there is current leaking into the system. My theory is that the current supplies the energy for the increased corrosion. Cu -2 electrons = Cu2+ This is the conversion from metal pipe to dissolve copper. The process produces current when active.
The copper in the hot and cold can be the same and this can indicate a problem before the water enters the house/dwelling

Shallow bores tend to be soft, have an acidic pH and be low in minerals. Rain water has a naturally acidic pH. If stored in a concrete tank they are often OK (no corrosion due to the concrete hardening the water).
When stored in a plastic or metal tank the corrosion occurs.
If an acid neutralising chemical is added to the storage tank the problem will cease. Re dose when the green/blue reappears.
Points to note: The corrosion is at it worst closest to the problem. (check current leakage around the site of the water leakage)
Solar water heating and gas heated water frequently have problems.

A. What you are describing sounds like a galvanic reaction. Make sure that dielectrics are installed (they look like a gnarled union) and if they are make sure that the rubber gaskets are good not allowing for contact between the copper and galvanized steel.