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topic 30479p3

Copper corrosion and blue water in residential water system

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A discussion started in 2004 but continuing through 2019

November 7, 2011

Q. I have had blue stain in my sinks for several years now. Have read all responses posted here and don't see any easy solution. I've found one commercial product out there that claims results. Does anyone have any comments on the sacrificial anode made by Copper Knight?

James Haberberger
- Leavenworth, Washington

November 24, 2011

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

Mohammed Ali, P.E.
- Danville, California

March 5, 2012

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!

Bob Gordon
- Metairie, Louisiana

March 11, 2012

Q. I have purchased a home in cape coral Florida. I have gutted the home and am told while it is gutted I should replace the plumbing. It now has copper water lines in the slab. The house was built in in 1972. There have not been any issues but I am told that in time these pipes will beginning springing leaks and I should run new pipes from the attic down to the faucets. Does anyone know if there is truth to this? I do not not have any blue green rings in my sinks as others had reported. Any assistance will be appreciated.


George Forte
- Cape Coral, Florida

March 26, 2012

Q. I own an old house with copper piping; we also have well water and have been told we have hard water. We have several leaks a year with blue corrosion at the leak site, and the area will be so thin that it just breaks and crumbles. Would a water softener correct this problem?

- RINGTOWN, Pennsylvania

March 30, 2012

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 sulfate/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.

ron schultz
- Detroit Michigan you s of a

August 20, 2012

Q. I have a home built in 1998. In the last 3 months we have had 4 "Pinhole" leaks in our copper pipes in unrelated areas of the house. Investigating online I see this is becoming an increasingly common problem in homes across the nation, and that the latest research leans towards water chemistry as the problem although no one yet has a definitive answer. My question related to the above topic is: What experiences have folks had with PEX piping. I see many folks are going this route, and I read that PEX has been the piping of choice in Scotland for more than 30 years, but I can find no reliable information about the long term history of PEX. I need to repipe my whole house, but I don't want to use copper again if I'm going to have the same problem in another 10 years.

Please help if you can!

Joe in NY

Joseph Peck
- Pound Ridge, New York, USA

Brass finish sink has a white film on it … electrolysis?

March 28, 2013

Q. I have a Hooker bathroom vanity and sink. The bowl is a baked on brass finish. It was installed during construction and has been in our powder room and used for 8 years. Then two days before New Years Eve this year, we noticed that water that sits in it leaves a white film which we cannot get off. The manufacturer said we can use regular toothpaste or SoftScrub on this bowl. Nothing works. I did fill it partway with vinegar and let it stand and some of it seemed to come off but not a lot. Two things have changed that may/may not be the cause. We installed a hot water recirculating pump in October. Then the first week in December we installed a non-electric Kinetico water softening system with a Chloramine Reduction System which has a large carbon filter. Since installing this we have noticed a green residue accumulate under my electric toothbrush and last week we noticed our bar sink (not used much) had a green residue, like calcium deposits only green, on the outside of the aerator. Kinetico has been out to look over the problem and claims it is not their system but thought maybe we have a electrolysis situation. He feels it is in our plumbing or that maybe the recirculating system is causing it. My thought is, why is it only showing up now? I hope someone has an answer before any damage is done.

E A McCoy
- Omaha

March 31, 2013

Hi EA.

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.


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

April 1, 2013

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?

E A McCoy [returning]
- Nebraska USA

April 8, 2013

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).

Marc Banks
Blacksmith - Boone, North Carolina, USA

October 9, 2013

Q. We had a new solar water heating system and on-demand water heater installed last November. Coincidentally, the town had just repaired water saddles on our street before redoing the road surface. Also, we had just upgraded to FibreOp on our tv/ internet. When we started to experience blue water from our taps, both hot and cold, we contacted the solar installers to see if there would be any system or electrical cause and they told us there shouldn't be. But here we are, almost a year later with the same problem and no idea how to go about fixing it. We don't remember the blue before this but had had a recent discolouration (brownish/greyish) in our water from the hot water tank that we had only had in operation for 8 years.
All the above information is very interesting but we are unclear as to the order of steps we should follow. City? Electrician? Plumber? Etc.
Thank you for any feedback or advice you may have.

Kathy Phillips
- Wolfville, Nova Scotia, Canada

Earth Battery

May 2, 2014

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.

Jamie Robb
- Dartmouth, Nova Scotia, Canada

August 6, 2014

thumbs up signIf 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.

Robert tonner
plumbing and heating - Glasgow,scotland

August 16, 2014

!! Hi, we had light blue water when we had a dysfunctional water softener installed in our house. I had professional water analysis done on our household softened & unsoftened drinking (tap) water.

The softened (tap) drinking water had copper level of 15 mg/L (EPA safe level is 1.3 mg/L), and also contained acetone. Unsoftened household water copper level was .05 mg/L. and did not contain acetone.

Our family had physical symptoms consistent with high copper ingestion including gastroenteritis, bloody diarrhea, nausea, vomiting, headaches, tachycardia, dermatitis, cognitive impairment. Symptoms started within weeks of the softener being installed and continued for the 7-month period that the softener was in our home. The water softener company failed to install a pressure regulator valve, which apparently caused the unit to become damaged and not function properly. After 7 months of having this dysfunctional unit in our home, the company took out the broken unit & replaced it with a new unit. After 2 weeks of the new unit softening our water, water analysis showed that softened water copper levels were at .06 mg/L. Our symptoms improved. My daughter now has IBD (Ulcer. Colitis) and I have cognitive impairment.

Later we discovered that the company who installed and maintained the water softener system, installed it without required permits (which if permits were pulled, the incorrect install would've been noticed by inspector). They also installed a system which is illegal in our city (it drains brine waste into the sink/sewer, which is illegal). If anyone has a water treatment system in their house and has noticed blue water, and physical symptoms described here, please let me know.

Tawny s [last name deleted for privacy by Editor]
- Los Angeles, California, USA

August 2014

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 publicly posting can weaken your case (my understanding is that if your lawyer receives opinions that do not support your view, s/he doesn't have to reveal it to the other side, but you must). Good luck, and speedy recovery.


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

July 23, 2015

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.

Chris smith
- el reno Oklahoma usa

September 5, 2015

Q. Hi, I live in a rental and there is a blue tinge to the cold water. I boil the water as I like to keep a jug of cold in the fridge; when it gets near the bottom of the jug there are blueish granules, residue. I have been in the property about three months. If I continue to drink this water is it likely to make me ill or do me damage. I am getting a bit worried about this; hopefully someone can reassure me that I will be okay. Many thanks, Gerry.

Gerry mcveigh
- Hamilton New Zealand

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


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Striving to live Aloha

December 14, 2015

Q. We just purchased our house 6 months ago. It was a custom built home in 2005. My husband loved the master bath, it came with a steam vent, lg ceiling fixture, & 3 side wall mount fixtures.

I'm blonde and have highlighted hair. After 6 weeks I have green tint to my hair. The salon said it must be chlorine, we have a whole house water purification system, charcoal tank kind. We have it serviced & checked. We have an on-demand hot water heater for the house. The salon got the green out of my hair and 3 weeks later it is green again! I noticed green residue on the ceiling shower head. Also there is substantial green corrosion on the copper pipe to the steam value. We are not on a well. The problem is the plumber doesn't think it is a corrosion problem because we are not on a well. The pH level is good and no chlorine was found. No one seems to be able to answer or willing to look. Is there a plumber in the area who can find a solution? Thanks.

Patrick Coleman
- Fallbrook, California

December 2015

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


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Striving to live Aloha

February 21, 2016

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.

barbara brandt
- Ewing, New Jersey, USA

May 21, 2016

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.

barbara brandt [returning]
- Ewing, New Jersey USA

August 2016

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.


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Striving to live Aloha

August 6, 2016

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.

jeff blair
- Omaha Nebraska USA

March 21, 2016

Q. Blue water on the floor outside the shower every morning and/or evening. Have no idea what it is, would this be the same thing? We don't know where it's coming from.

Rebekah Foote
- Perth, WA, Australia

March 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 :-)


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Striving to live Aloha

June 20, 2017

Q. Hello. We recently (3 weeks ago now I think) had a water softener installed as we live in north London and have very hard water. We have also refitted our house with new appliances, a new combi boiler, and just had the downstairs bathroom redone. so we've invested a lot of money!
So far the water softener seems fine. But last week we went on vacation. And we have come back to find a blue stain in the bath, under the bottom of the u-bend in the shower hose.
so I can't imagine this is anything other than the water softener, maybe being set at too high a setting? the bath was redone 1 year ago, and the combi boiler was put in 1.5 years ago. no prior history of staining before the water softener. there are no other blue stains we've found. thanks very much,

Michael carrton
- London, England

May 19, 2018

Q. Hi. We have blue green staining as well. 15 year old home and one owner. Piped with copper and electric water heater and private well (330 ft deep). Replaced water heater in year 3 and year 6 and in year 15 (this year). Started noticing blue green staining shorty after second water heater install mostly on the hot water side. NO HOLES in the pipes. We paid for complete water testing -- all checked out fine including pH. Some turbidity.

We installed a triple 2.5 x 10 water filtration (sediment + GAC + Carbon Block) and swap them out every three months or so. The sediment more often. House is grounded appropriately (to well casing), but somehow copper water pipe is bonded to the neutral. Physically disconnected the water heater and pump from the electrical system, but copper pipe still bonded. Switched off each breaker individually, copper pipe still bonded. Drained water from copper pipe and disconnected pipe from pump (to see of water is carrying the charge) … copper pipe still bonded. I have replaced pieces of the copper with PEX when installing water filtration and new water heater. AND … we are still getting blue green water staining with NO pin holes/leaks in pipes. Any thoughts/solutions before I re-plumb the house with PEX.

LR Squires
- St. John's, NL

December 14, 2019

Q. Hi,
We replaced our old water softener (it was past six months old) with a new one last week. Since then the water in all the faucets is blue in color. Tried leaving the taps on for few minutes to drain out the water in the pipes, but no difference. We thought the water softener was defective so bought a new one and had a plumber replace the cartridge but the water remains blue and has a metallic taste. So definitely it's not the softener. We have copper piping in the house.
I don't know if there's a connection but at the same time when I changed the first water softener, I replaced the water filter cartridge behind my refrigerator as well.
The water was fine until I replaced the water softener filter with a new one. I am supposed to change it every six months. Have done it in the past. No idea what happened this time.
Please help.

Sushma Roy
- Bay Area, California, USA

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