Copper corrosion and blue water in residential water system, p2

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.

Ed. note: Please note that it was a reader, not the editor, who recommended these "Oscillating Rings". I'm not familiar with them, but the explanation on their web page struck me as quite silly.

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. Within 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 ⇦this on eBay or Amazon [affil links] 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.

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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.

? What has been the copper content of the water in some of these cases in part per million. The EPA acceptable level is 1.3 ppm.

A. I am a registered corrosion engineer in California and have worked on several copper corrosion issues including a very famous blue water problem in Northern CA.

Internal corrosion of copper pipes, which causes blue water, has nothing to do with electrical grounding. If stray currents will be involved in copper corrosion (very rare) it will be external corrosion of the copper pipes not internal.

My experience is that internal corrosion is generally caused by bacterial corrosion (generally stagnant water or water with inadequate residual chlorine), leftover flux during pipe installation, erosion corrosion due to high water velocity such as in recirculating water in hot water systems.

Not knowing all the details, I can suggest the following:
Install dielectric unions between the water heater and the copper pipes.
Turn off the recirculating water pump and see if the problem goes away in the hot water pipes.
Check the residual chlorine at the taps and see if it conforms to the water District standards (greater than 1-2 ppm comes to mind)
If the problem still persists, call a local corrosion engineer. Good Luck

A. FYI:
In 4/2006 installed a Paloma tankless water heater for whole house-love it. In 1/2007 installed Kinetico whole house salt exchange water softener.
Within about a year green stains gradually built up in both bathroom tubs/shower areas. City water tested as normal. Copper bypasses were placed outside where the softener was installed with no improvement.
Company finally checked household water which confirmed higher copper levels. More copper wire bypasses were placed around water heater which led to some improvement.
Several (4-6) months ago we noticed cold water input copper pipe abutted the metal tank housing where we then stuffed insulation.
So far it appears we corrected the problem-fingers crossed!

A. In 1969 or 70 after Christmas vacation I was getting ready for a morning meeting getting a big drink at a water cooler and then before I filled a soda pop can full of water, I allowed my boss behind me in line to get a drink. 20 minutes later I excused myself from the meeting to go to health service, noting I feel sick from that drink of water. My boss joined me. I declined an offer to pump my stomach; I shouldn't have! My boss left; I later learned he had gone to men's room and vomited. He felt better; I didn't; I felt rotten all day. When I poured the soda pop can contents into a glass, the mush was too opaque to see thru, a mix of green, mint green, and blue-green.

The investigation of the problematic water cooler found:
* In piping the water line to the cooler, the plumber used one plastic fitting in what was otherwise an all copper line
* That to provide a ground connection to d c [direct current] signaling function of a tie trunk circuit of a PBX switcher in the lab at this Bell Telephone Labs location, the design people had run a wire from the PBX to this nearby water cooler. And
* The 4 day weekend was long enough for a lot of nasty electrolysis across that plastic fitting.

I recall in electrolysis experiments I did, using ac didn't do much but using dc much more happened!

One can get DC out of AC by using a rectifier; crystal [radio] sets used a crystal to rectify radio frequency AC into varying [at audio frequencies] DC. Some of these crystal sets used the crystalline structure of steel razor blades. It seems possible to me that nearby radio transmitters [like home electronics or cel phones] or high voltage transmission lines can induce signals into metal water pipes with some flow thru the water at dielectric junctions to copper sulphate/ite crystals in contact with inside surface of metal pipe, thus resulting in rectified [dc] flow.

Another chemical involved in some municipal water is phosphoric acid which is added to the "finished" water to keep lead piping from dissolving into the potable water. Detroit Water & Sewerage Department is one that does this but refuses to say so in their Water Quality Reports. This acid in the water may increase its conductivity, causing increased electrolysis effect.

Hi E A.

A. Anything is possible and your sink may be suffering from the chemical or electrical issues discussed here, but I tend to doubt it.

The "baked on" finish on your brass sink is almost surely a lacquer or clearcoat of some sort, and it would not seem strange that after 8 years of use, or an incident of abuse (some sort of chemical like turpentine rags in the sink), for the clearcoat to "whiten". If that were the case, you would not be able to clean it off with anything because it wouldn't be a stain on the surface but discoloration of the clearcoat itself -- and that seems to match your situation as well. It's probably possible, but perhaps impractical, to strip the clearcoating and re-apply it (you obviously couldn't use an oven-bake clearcoat). Maybe if you include a photo people will be better able to advise if it looks like failure of the clearcoat. Good luck.

Regards,

Q. The powder room gets very little use and certainly has had no chemical in or around it as the countertop is marble. I have filled the sink to different levels 3 times, each one higher than the one before with plain water. It leaves a white coating each time. Is there something in the softened water that would dissolve the clearcoat?

A. That does look like something in your tap water interacting with the clear coat.

Get your tap water tested.
Also get some pH test strips and see if your water is swinging too far towards acid or base (pH of 7 is neutral).

A. Sounds like your house is somehow reproducing a earth battery effect two dissimilar metals, such as iron and copper lie in damp soil they can tap telluric currents creating a current leading to electrolysis and pin holes A earth type battery set up was used to power telegraphs in the early days.

If you all stayed in Scotland you could replace all your copper supply pipes in barrier pipe (plastic) which gets a 25-year guarantee and copper only gets 15 years in Scotland.

A. Sorry for your troubles Tawny. If you are considering legal action though, please contact a lawyer and let him/her handle it; s/he will explain that public posts can weaken your case. My limited understanding of this is that if your lawyer receives opinions contrary to your view, s/he doesn't have to reveal it to the other side because it's "work product"; but if you are asked whether you received such replies, you must truthfully answer. Good luck, and speedy recovery.

Regards,

A. A water softener is not made for drinking water. It prevents scale build up. It does not stop things that dissolve copper. Drinking water is made from a reverse osmosis which will make it drinkable . Water softeners soften the water … if the water is soft then it's not the softener causing blue water. High TDS dissolves brass fittings. Best pipe to use is pex with plastic fittings. If you have copper, check grounds and use poly(?) to coat your lines to help slow down the corrosion while trying to figure out the answer.

Ed. note: Some of the electricians above have claimed above, that water softeners can be a problem not due to the water chemistry but because the water main was previously being used as a ground and installing the water softener can interrupt that metallic grounding path.

A. Hi Gerry. Sorry, I wouldn't drink it. Buy bottled water or contact the county health department or wherever monitors public water supplies.

Regards,

A. Hi. I'd bet that the county health department will analyze your water for free. It may still turn your hair green, but at least you'd know whether it's safe to drink :-)

Regards,

A. I had a new electric water heater installed, a new gas heater and new plastic piping. The contractor (on his own) after a utility company inspection, put in a new copper water pipe to the new water heater. The water heater is grounded. The person who installed the water heater did not run a new line as I specified but used the line for a basement light. He was paid to upgrade all the lines including well pump but did not so they are from 1951. I found this out in 2015. Without knowing I had a copper pipe, my bath water was blue so I checked to see the pipes in the basement and found the copper pipe with corrosion around all of the welds. Neighbor came in and said it was new pipe. Meanwhile, the water heater is running brown and in a real mess. It was only 5 months old. This house was bought in 2001 and had good water. When that copper pipe was installed the mess began.

Q. My house was built in 1928 and I hired electricians and plumbers to bring it to code after 4 years. No problem with corrosion or blue water. Changed to PEX for all basement plumbing. Gutted bathroom but not tub. Porcelain over cast iron. New Heating system also used PEX. Bought new electric water heater to replace gas (vented into chimney was not good). Found green and blue water after utility company visited and discovered copper pipe from well to water heater. Sense here is for years no blue and green water or corrosion even with well. Now with copper pipe supplying NEW water heater (electric) it had a life of 4 years. I also noticed installer used wiring and circuit from the light in that area rather then a new circuit and I had a 20 amp board installed but had a marginal electrician twice. Water is a little acidic.
Had all cast iron plumbing replaced. Tub shows corrosion around new chrome fixture. I am replacing water heater and will use black pex. Not sure if I should go back to endure expense of a new gas appliance with venting or try electric again without the copper pipe.

A. Hi Barbara. If your tub is connected to everything only with PEX it is not possible for galvanic currents to travel to it. It should be fine henceforth.

I don't think corrosion is inherent with electric water heater; something is doubtless wrong, but I wouldn't know what.

Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 2016

A. It sounds like this forced hot water is a tankless water heater? If so get rid of it and use a tank type. If not it may have an electric recirculating line, look at that.
Also look at type of copper and solder used.
No dissimilar metals should be used.
I am not an electrical expert but I disagree with using copper water pipes for grounding because there is always a current traveling through them which causes corrosion.
Compare water before the meter vs. after to locate source of problem.
LEADFREE COPPER IS THE SAFEST POTABLE WATER SYSTEM.

Jeff blair
- Omaha Nebraska USA
August 6, 2016

? Hi Rebekah. Apologies but I don't understand the situation you are trying to describe. We can either hope that another reader understood, or please write a couple of paragraphs :-)

Regards,