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topic 30479

Copper corrosion and blue water in residential water system

A discussion started in 2004 but continuing through 2018


Q. I am a civil engineer trying to figure out the following problem for a high-end home builder. After just finishing this exclusive house, the owner started complaining about blue water in their domestic water system. The local water authority was contacted and confirmed through water sample analysis that it was copper corrosion, and happening only at the referenced house. Suspecting potential electrolysis due to improper grounding of the electric wiring, an independent electrician was hired and confirmed that grounding was correct. Further inspection revealed that the copper piping from the hot water heater was connected to galvanized steel reducers and the connection was corroding and starting to leak. Does that explain the blue/green water in the system? Both the hot and cold water had the coloring, with the cold water having more pronounced evidence of the bluish tint! Due to the size of the house, the hot water heater is part of a forced hot water system to ensure hot water is available instantly at any location in the house. Any explanation for the copper corrosion? Is it electrolysis due to improper electric grounding even though no evidence was found? Is it due to the galvanic corrosion from the water heater? Any ideas?

Tony Warrick
civil engineer - Bethlehem, Pennsylvania


A. This is a strange problem, and sounds to me like it is almost surely related to improper grounding of electrical service causing electrolytic dissolution of copper. Can you turn the power off at the main, and run the cold water, to see if it clears up?

Both galvanizing (zinc) and the pipe underlying the galvanized surface (steel) are anodic to copper. These materials go into solution preferentially to copper. Remember the high school chemistry experiment of putting a nail in copper sulphate: the copper deposits on the nail because iron goes into solution to pull the copper out, not vice versa. The very rapid failure of the galvanized joint may well also be due to the electrolytic action from the electrical system.

Ted Mooney, Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey
Striving to live "Aloha"


A. Another possibility: Maybe the electrical system is grounded OK, but there is an appliance with a small earth leakage - not a full-blown earth fault that would trip a protection device - and the small earth leakage is causing the corrosion. Certainly sounds as though SOMEWHERE there is a source of electric current through the water pipework.

Bill Reynolds
Bill Reynolds
   consultant metallurgist
Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.


A. If you can find someone with a clamp-on Ammeter large enough and sensitive enough, you can check the water supply-pipe for current flow. Sounds like an interesting problem, please let us know what you find.

Tom Gallant
- Long Beach, California

Ed. note: Please also see response below from Steven W of Santa Ana, California who feels that this is a water chemistry issue, not an electrical one.


Q. I have a 10 year old home, that has had 5 leaks in the copper water pipes. Always the cold water lines. To make matters worse, the plumbing is run under a concrete slab. 5 different plumbers think there is some sort of electrolysis causing the corrosion of the cold water lines. But, none have any idea how to stop the problem. Evidently, this can be a problem with electric hot water heaters, but ours is gas. You can even feel an electric tingle if you touch a cold water pipe. Any ideas on how to fix this?

Shirley Canfield
homeowner - Alpine, Texas


A. Hi Shirley Canfield..

I had the same problem. The earth on your house should read less than 1,ohm from any power socket to ground. The earth connection should be made via a dedicated earth cable from your consumer unit to ground via a buried metal spike. If you can feel a tingle ( it's safer to use a multimeter tester) when you touch your water pipes, this is due to the voltage leak going to earth via your pipes rather than the correct route through the earth wire. Try switching off each mains fuse trip one at a time until you locate the circuit that is responsible for the voltage leak (tingle should disappear).Once you have located the offending circuit,unplug each appliance on that circuit until the leaky appliance is identified and have it repaired on bin it. You should then have your earth connection checked out.

Good Luck.

Keith (UK).

Note this sort of earth leak will pepper your copper pipe with pinholes wherever in comes into contact with moist earth, (the higher the voltage, the quicker the holes).

Keith Cooper
- England


Q. I have a similar problem in that I have a .75 inch cold water copper pipe under my slab approx. 20 feet long and there have been 5 separate pin hold leaks in this section over a 6 year period. To my knowledge, there have not been any leaks in the other sections of the house or the hot water pipe. The house is 30 yrs. old. Any suggestions ?


William Hutt
- Dallas, Texas

2004 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. 2 years ago I was called to investigate water in a 1st floor ceiling. The house is approx. 25 years old with copper piping. There is a 2nd floor bathroom above the wet ceiling. I investigated and saw no evidence of a fixture leak. We took the ceiling apart and found pin holes in a few locations with green stains nowhere near the sweated joints. The house has city water. My first thought was low pH and would have pursued this if it were a well system. We had a plumbing contractor in to repair the pipes and analyze the situation. They stated it was caused by electrolysis. They proceeded and repaired the pipes that were visible. I explained to the homeowner ( not fully understanding electrolysis) the situation and said we should get an electrician in to look at the bonding, they did so and he said everything was ok. @ years later the customer called me back and said the leak reappeared in the same area. I visited the site and found in the basement near the service panel more pin holes. I have our electrical contractor meeting me next Monday. I need any info on this including possible causes, testing and solutions.

Thank You,

contractor/designer/builder - NEW HARTFORD, Connecticut

The Blue Death
from Abe Books



A. What is occurring in your plumbing system is refer to as "Blue Water Syndrome". It is not an electrolysis problem but a water chemistry issue. All new copper piping dissolves at a rate of .001-.003 per inch, per year during the first few years of installation. Blue water occurs many times in homes which are larger and only a few occupants or if a soft water conditioner was installed before the piping was ever used and is over softening the water. There are a few other reasons why you can have an accelerated rate of copper dissolving as well. Some of which is if the pH is below 6.5 copper solvency occurs. In addition the changes made as part of the EPA Safe Water Act of 1991 removing of NOM's from the water has caused a lack of the protective patina which occurs as the copper is dissolving.

Steven Wann
- Santa Ana, California

2005 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I have a newly constructed home that is just over a year old and has excessive blue-green staining of sinks, tubs, tile etc. I had the water tested and it is municipal water that tests OK. I have been told by the chemist as well as a water treatment specialist that my water is corrosive and the problem has to be electrolysis. My electrical system has been tested and has been found to lose amperage to grounds (e.g.copper pipes, etc.) instead of the neutral ground. However thus far the source has not been isolated. I'm trying to find out the places or areas within the house that people have had experience with this occurring. Can it only be in the electrical system? Can it be in the plumbing system? Can it have to with the electrical utility company or the water company outside my house? Can it have anything to do with the audio-visual wiring or phone or computer network wiring somehow creating a ground loop within the house? I am desperate to hear from anybody who has encountered a similar problem and what the possible causes and solutions are.

Thank you.

Stephen Gal
homeowner - Wyckoff, New Jersey


Q. We have a new construction home that is 2 years old. We are on a private well and the water is extremely hard. The first year we dealt with hard water deposits and staining, and then we installed a water softening system. That helped reduce that problem, and now a year later we have blue water stains indicating copper corrosion.

We have not done any testing to discover the underlying reason for this problem (we are still gathering info). My question is: Assuming the reason is discovered and addressed; is there a way to stop the corrosion or are we destined to have leaky pipes with the likelihood of having to replace them?

Debra Curry
- Rochester, Washington


Q. I have an artesian well and the pH was low a while back so it tinted my bath tub and my hair a greenish color. Not so fun. The pH has been normal for a while now but the water is still turning my hair a funny greenish tinted color. If anyone knows how to make it so the corroded copper stops turning things green it would be so awesome. please help!

Christine C [last name deleted for privacy by Editor]
student - Concord, New Hampshire


Q. I have .3 to .9 volts a/c on my external water faucets, what could cause this? I am experiencing pin holes in copper water pipes in a nine year old home. From the looks of the pipe, it appears to be electrolysis. The first leak appeared 2 years ago and the latest one week ago. I have a water well with excellent water and live in rural central Texas. The electric company came out and removed the meter and we disconnected the breaker at the well. With no electricity possible to the house, I still measured the .3 to .9 volts at the faucet.
Any ideas? Help.

James Prosise
rancher - Mullin, Texas


Q. In my 45 year old house we noticed blue water in our bathtub recently when filled to 8-10 in. The city and province ( state) have all tested and declare the water OK to drink. Then ran a hose from the fire hydrant into my white bathtub, by passing my system, and the water was still blue. tests for copper all indicate level OK for drinking water. my neighbor has the same problem. Extensive testing for organic and non organic and metals all show normal levels for drinking water.
any thoughts?
any help would be welcome!

Alistair Stewart
- Toronto, Ontario, Canada

Practical Grounding, Bonding, Shielding and Surge Protection
from Abe Books



A. Too many earths could explain most of these problems. I am an electrician turned science technician. Electrolysis is caused by DC current only. I found pin hole leaks under an earth clamp. My explanation is that a DC current is flowing from one earth on the water system to a second earth also connected to the water system. A DC voltage often exists between distant earths. Examples of separate earths are:

The electricity substation earth rod.
A supply pole earth wire.
A buried water or drain pipe.
A buried cable sheath.
The steel frame of a building.
A machine,pump or boiler standing in water or on the ground.
Telephone or other communication system earths.

Electricity will flow through the water as well as the copper. Modern regulations mean that the water system is earthed by several of these sources of varying potential at various points. Now can someone suggest a solution?

Eric Swift
- St. Briavels, Gloucestershire, UK


Q. I am facing a similar problem. There is a tingling sensation when we try to open the taps in the house - kitchen, bathroom … but it lasts only a few seconds - 10-20 sec. Then it's gone for a few hours. The electrician checked the electrical wiring but seems fine. still struggling with the problem.
If anyone can suggest I would be happy . If I find a solution, I will post it to you.

Milind, G.
- Delhi, India


Q. I am curious about the forming up of the 'Blue/green' water in copper pipelines, just wondering if these pipes are soak in water before a huge tank to allow these pipe to be oxidised will it help?
Basing on my understanding, these phenomena is only subjected to NEW copper pipelines.
My prime concern is to get an answer not by purging the pipelines or flushing the pipes with chemicals.

Richard Nam
- Singapore


Q. My problem is also with copper pipe failing, my Question is will a strong radio signal promote electrolysis in copper pipes? If it can does anyone have any suggestions?

Miles Berry
- Meridian, Idaho


Q. I'm not seeing many answers here, but I will post what I'm seeing and see if it helps anyone.

My house is 6 months old and it gets used only every few weeks. Every time we have returned the water will flow bluish and you can find blue crystals in the aerators and showerheads after running the water. The crystals look much like copper sulfate.

The water supply comes through black Polyethylene piping and connects to the copper system in the house. The electrical system is not connected to the copper pipe at all, but is grounded via grounding rod outside. There is a DC potential of ~0.5 volts between the metal spikes embedded in my foundation and the copper piping in the house. When the main circuit breaker is turned off, the potential remains.

Add to all this that my foundation is insulated on the outside using pink styrofoam insulation, but is attached using special nails with 2" diameter heads. I measured the potential between the nails and the electrical ground rod to be about 0.3 volts (the measured points were only 12" apart). This may be the multiple grounds that Eric referred to above.

My big problem is that my shower heads are clogging and it appears that I will have failing pipes in the near future if this is not resolved.

Local water quality is excellent with a PH around 7.0. Neighbors and local plumbers do not have/have not seen this problem.

So if I have a distant earth problem, will providing a better ground than the foundation be the solution? or will I just create new problems by grounding the pipes to a new ground rod.

I'm going to get to the bottom of this so any leads from here are greatly appreciated. A solution is even better.

William Mahony
- Limerick, Maine


Q. Following Steven Wann's answer, I have another question.
We have a new vacation home in NH, and are experiencing the blue water problem. I called the town water person (we town water not a well), and he said they keep their pH at about 8, so that should not cause the copper corrosion.
Our electrical system is properly grounded, as far as I am told.

Is there another answer to this blue water thing? We are going to have the state lab test our water for potability.

The toilet tanks show blue tinted water, and the toilet bowls of the lesser used bathrooms have a blue stain that is difficult to remove. This does not occur in the bathrooms that have been used more regularly, say once or twice a month.

Any suggestions?

Thank you.

Judith Leader
- Lexington, Massachusetts


A. I do have a solution although it is costly. Replace the copper pipe system with a PEX system. If you are on a slab, run the pipes down from the ceiling. PEX has been used in Scotland for 30 years very successfully. It is being used in new developments in the local area. I am a homeowner and live in a 100 unit duplex/triplex set of condominiums. Built mainly in the 1976 to 1985 era. We have had 5 major pinhole leaks in copper pipes in last two years. Three of the leaks were under cement slabs. I have been trying to find the cause with no success. I have talked with water analysis engineers, had lab work done on the water and the pipes and I still have no answers about cause and repair. I have discussed the problem with people from Alaska to Florida. No solutions After two years of research I have come to the conclusion that copper pipes and water don't work together and nobody knows why.

Donald H Leo
- Lacey, Washington


Q. I have been living in the same house for 26 years using the same artesian well and copper water pipe system without any significant problem. Over the past three years we have been getting a bluish-green stain on our white bathroom fixtures. It has gotten worse and worse to the point of frequent cleanings and I'm worrying about the safety of the water.

I recently had the water tested and it was normal except for the pH level which was 5.8; however, 26 years ago it was 5.6 and I had no staining problems then. The only thing I done to the system recently was about four years ago the submersible pump was professionally replaced.

Any ideas?

Robert DesRochers
- Westford, Massachusetts

National Electric Code
from Abe Books



A. I'm an electrician, I can only say what a properly grounded system should consist of, according to the NEC. The neutral (in the main panel or first main disconnect) should be grounded to the Copper water main before the water meter(the water meter should also have a jumper around it,to provide continuity if the meter is replaced).This is one method other methods are a copper wire embedded in the footing and bonded to the rebar(UFER GROUND), or if a steel building, using a steel beam as the main ground. The code then requires an additional(supplementary) grounding rod(actually two unless the electrician can prove that the one rod is 25 ohms or less to ground). So usually two 8' ground rods are driven and connected to the water pipe as well.

Now a jumper of #6 copper wire can be placed from the cold water pipe to the hot water pipe above the water heater. Any other systems should all be bonded back to the same point(before the water meter)this is the crucial step that eliminates any potential ground loops. Any piping system which you believe could become energized is permitted to be grounded back to the water main. The NEC gives specific wire sizes for telephone(Communication) and Cable(CATV) grounding.

There's also a line of research in which childhood leukemia is being investigated in which small electric currents flowing from the supply to the drain piping via a person touching the faucet handles while in the tub. EC&M magazine published this article in about Sept 2006 -- they're on the web as well.

Finally, electricity wants to get back to the source(the transformer which it comes from)and the ground(earth) is not a very good path, the copper wire which is the neutral usually covers 90% of this, its the other 10% we're worried about. However if lightning were to strike you'll be very glad to have a well grounded system.

John Andreson
- Denville, New Jersey


Q. My husband and I recently bought what we thought was our dream home until we found blue granules in our toilet tank and toilets and then started noticing a blue spot in one of our sinks. Our community is about 1 year old and several homes are having the same issue. The water has been tested at the hydrant and tests normally(so our H20 supplier says)and the homes have been tested and are properly grounded. What else could be the problem? Also, how hard would it be to reinstall plumbing for an entire home, if it is even possible? I have children and a newborn and have read that it is toxic to ingest a certain amount. Does anybody have any other solutions for me to try?

Sarah Bowerman
new home owner - Hutto, Texas


A. While proper grounding is important one thing that I have noticed in my area involves the water chemistry. I have a handful of customers in a new housing development that are seeing this staining. Some have water softeners and some don't. The problem comes from the incoming water. People hear that the pH is around 7.2 (pretty neutral) and assume it has to be the electrical system. I disagree. You need to have a water analysis done and look for a few important things. What is the copper level at? What is the Dissolved Oxygen level? The oxygen will start the corrosion process of the copper that is in solution and in some cases from the plumbing itself. You are left with a Blue-Green stain or build up and in some cases pin holes in your plumbing.

Chris Ray
- Omaha, Nebraska


! I investigated a blue water issue in a town home community my company built several years ago. Several homes in the community (but not all) had the blue granules and staining. We also found evidence of the same phenomenon in a neighboring single family community. We used the same materials and contractors in several Villages, but only had the issue in one. We tested the water, and while the copper content was higher than normal it tested well within the EPA's standards. We had State plumbing and electrical inspectors check the community and all was found to be done correctly (no grounding issues and proper materials and installation). Nothing we did alleviated the problem. I called a chemist at a neighboring Village's water department and was told that some Villages use a chemical to seal their pipes periodically if high levels of lead are found. This chemist said that her Village did not use this chemical because it causes copper to corrode. When I mentioned this to the water department of the Village we had the issue in, they ceased to request any more exploration into the issue by my company. I believe it is still an issue in that community to this day (7 years later), but we have not been involved in it for the last five years.

John Yanez
warranty manager - South Elgin, Illinois


A. I came across the following information from the Washington Suburban Sanitary Commission. It may help explain some of the copper pipe problems in new housing:

"Inadequate Flushing and Stagnant Water
Formation of a uniform, protective film on copper also depends upon proper flushing of the system to remove construction debris from the inside of the tubing. Clean inside surfaces are essential to the development of protective films. If debris is allowed to remain in place on the inside surface for an extended period of time early in the life of the system, two to three months for example, corrosion can develop beneath the deposits [6,14]. Once started, this type of under deposit corrosion@ will likely continue resulting eventually in a leak failure.

A related cause of copper corrosion can occur when a completed plumbing system is allowed to remain stagnant with residual water for an extended period of time following flushing and testing. This problem has been discovered and identified most often in tract homes and apartment complexes that are often constructed, but not occupied, for a period of time [13]. The initial stages of protective film formation on a clean copper tube surface depend upon a frequent flow of water through the system to promote uniform film growth. Stagnant conditions for extended periods of time, especially when the system is partially filled, can cause non-uniform film development and corrosion depending upon the source of water.

An example of stagnant water induced corrosion is shown in Figure 6. The copper tube sample shown is from a horizontal section of 3/4 inch Type M cold water tube removed from an apartment complex that had been tested for leaks, but remained unused for several months. After two years, leaks began to develop in the plumbing. The upper half of the tube is positioned at the top in the photograph. A residual amount of water remained in the tube following testing, resulting in the growth of a non-uniform corrosion film in the bottom half of the tube. The yellow arrow indicates pitting corrosion that occurred at the water line under the stagnant conditions. This is another example of under deposit corrosion."
Brian Crawford
- Tupper Lake, New York


Q. Our house in Edinburg, Texas was built in 1996 and we bought it in 2000. I never dreamed a less than 5 year old house would have problems with the water pipes. We put in a water softener at that time, too, but it does not to appear to have helped. We recently went away for the Thanksgiving holiday and returned to a flooded kitchen, DR & LR.

The insurance company will help with the damaged drywall, cabinets, etc, and I paid for the water line repair. However, I am now trying to decide whether to change out all of the water lines.

What are your recommendations?

Jackie Michel
student - Edinburg, Texas

August 5, 2008

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.

Rishi Dwivedi
- Flushing/NY/Queens, New York

sidebar 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.


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey
Striving to live "Aloha"

August 27, 2008

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.

H. Hancock
- Austin, Texas

September 26, 2008

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 deg. 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.

Allen C. Willems
engineer - Manitowoc, Wisconsin

March 26, 2009

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.

Benjamin Du
- Torrance, California

June 22, 2009

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.

Jerry Ringtadt
- San Diego, California

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