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Participant

Join Date: Apr 2012
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High Copper Content In Domestic Water

04/19/2012 10:35 AM

I have a new complex that has started to show signs of discolored water yellowish in color in our domestic water supply. After testing before and after our water softener we found that there are high levels of copper above the MCL of 1.3. Could this be an effect of electrolysis or is the softener causing the decay of the copper piping. The system is all copper and is grounded in only one place that I am aware of at the incoming main. Any suggestions would be helpful?

SAMPLE #LEVELLOCATIONBEFORE/AFTER SOFTENERCHLORINECHLORINEALKALINITYHARDNESSPHTEMPERATUREIRONCOPPER
FREETOTAL
WATER PLANTN/A1.31.52403307.36700.08
1BASEMENTAFTER METERBEFORE0.70.92343327.57400.07
2BASEMENTAFTER RPZBEFORE0.91.12383307.87500.09
3BASEMENTMIDDLE (BEFORE SOFTENER)BEFORE1.01.22323307.87400.09
4BASEMENTBREAK ROOM (AFTER SOFTENER)AFTER0.00.123427.2730.020.71
51ST FLOORPROBATION NORTH (AFTER SOFTENER)AFTER0.00.123827.2730.031.33
61ST FLOORKITCHEN (CENTER)AFTER0.00.123427.3750.060.42
71ST FLOORKITCHEN STATES ATTORNEY (WEST)AFTER0.00.123227.5760.070.41
82ND FLOORKITCHEN JURY ROOM (NORTH)AFTER0.00.123427.57701.26
92ND FLOORKITCHEN (SOUTH EAST)AFTER0.00.123627.5750.061.42
102ND FLOORJANITORS CLOSET (SOUTHWEST)AFTER0.00.124027.57500.32
112ND FLOORWATER FOUNTAINAFTER0.00.124227.5730.153.01
=BEFORE SOFTENER
=AFTER SOFTENER
COPPER MCL = 1.3
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#1

Re: High Copper Content In Domestic Water

04/19/2012 11:05 AM

Just guessing I would say there is some electrical appliance grounded to the copper water line....The Ph doesn't appear to be acidic enough to cause degradation in the lines...I would disconnect system ground and test for voltage, then hunt it down...

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#2

Re: High Copper Content In Domestic Water

04/19/2012 11:50 AM
  • Get the facility's electrical installation inspected, looking in particular for final circuits where the earth and the neutral connections have been inadvertently crossed over. As soon as they are identified, correct these faults.
  • If the electrical installation is TN-C, TN-S or TN-C-S earthing, then get the local utility supplier to inspect and remedy any part of its installation upstream of the premises where there is a connection in the neutral line that is "dirty", leading to voltage drop on the incoming supply and the possibility of electric shocks from the outer metal cases of appliances and fixed, earthed plant.
  • Review the electrical earthing arrangements at the facility, re-running, if necessary, the earth connection to the pipework to a separate local earth electrode in the area so as to make a TT earthing system for the pipework.
  • Follow the local electrical code in all the above; if the installation were in the UK this code would be British Standard 7671. If in doubt, consult a qualified local electrician with inspection experience.

Otherwise, the problem will reveal itself with a burst pipe at an undetermined point in the future.

Do report back on the findings.

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#3

Re: High Copper Content In Domestic Water

04/19/2012 10:41 PM

Water is naturally corrosive and if you remove all the hardness the corrosivity of the water increases, it is not simply a function of pH. Research Langelier Saturation Index. Notice that where you have high levels of hardness, the measured copper in the water is correspondingly low.

Corrosivity is also a function of temperature. Those are very high temps for a cold water drinking water supply. When you took your tests did you let the tap run until the water was a cold consistent temperature? Standing water in copper pipes will increase the copper levels, and thus should not be consumed, let the tap or fountain run for a while. The temp at the plant is 67F while it's almost 10F higher elsewhere.

A few thoughts on this subject.

Cheers

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#4
In reply to #3

Re: High Copper Content In Domestic Water

04/20/2012 12:48 AM

Very correct and GA. It is also something that is underestimated in softened water. The loss of protection from the Ca++ deposits on interior of the plumbing can be serious from not only copper but also lead. Further, one may have to consider the side effects of the added sodium if they are on restricted sodium diets.

I have tried to work out the LI based on a conductivity of 524 μS/cm (assuming that the total alkalinity and total hardness represent 90% of dissolved ions) and TDS based on the conductivity x 0.6. For the incoming raw water the LI is 0.47 and the water with the highest copper has an LI of -1.8. The raw unsoftened water will provide a barrier so copper will not migrate into the water and the softened water with a negative 1.8 Index is extremely corrosive. The TDS is an educated guess and an actual TDS may create different indices. FYI

The solution may be to separate the softened water to all the cold supply for drinking and just soften the hot water for the benefits of soft water. As an interim solution, the OP should advise all to run the taps for several minutes to flush the built up concentrations of copper and lead. Keeping a tap open to continuously flush the main lines may also be a strategy. Water consumption may be an issue so the Op will have to judge the solution he wants.

There is an added strategy that can also be employed and that is to feed polyphosphate (PP) solution into the water supply on a continuous basis. The PP will form a monomer coating on the interior of the plumbing and thus some protection from corrosion.

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#7
In reply to #4

Re: High Copper Content In Domestic Water

04/20/2012 7:29 AM

I am going to research the polyphosphate with our chemical supplier and see if this is a feasible option. Our chemical supplier has noted that it may take several months of running hard water to build up enough calcium in the plumbing but I am concerned about the hard water running through my boilers for this long period of time. I will discuss with the boiler rep. to ensure we are not voiding our warranty. Short term we will flush the system at the fountains daily and continue to test for contaminents. This is the first time I have used the CR4 forum. It seems to be a very good resource to exchange knowledge. I hope I can be of help to others in the future.

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#10
In reply to #7

Re: High Copper Content In Domestic Water

04/20/2012 11:58 AM

PP is a common strategy for chicken farms where they want the chickens to get much of their dietary calcium from the water. Softening the water just removes the desired calcium so they use PP to sequester the calcium and prevent over encrustation problems. Here is at least one article and use in potable water situations.

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#15
In reply to #10

Re: High Copper Content In Domestic Water

04/21/2012 4:46 PM

Thanks for the information and link. I work on a poultry farm at the moment, and we are having encrustation problems in the hatchery which plugs the mister nozzles. There has been discussion about installing a RO unit just for the hatchery, but that is going to be relatively large and costly.

PP may be the way to go vs RO, I'll certainly discuss it at work.

Cheers,

Duane

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#17
In reply to #4

Re: High Copper Content In Domestic Water

04/23/2012 4:31 PM

kevinm,

You think a LSI (Langelier Saturation Index) of -1.8 is "extremely corrosive" ?...

Well, several months ago I did some water testing in a residential building in Manhattan. The LSI of the incoming water being provided by the City's water distribution system was - 3.90. Now THAT'S Corrosive!

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#18
In reply to #17

Re: High Copper Content In Domestic Water

04/23/2012 5:30 PM

Agreed! The usual interpretation of extreme levels of encrustation or corrosivity when using the LI for domestic water plumbing is anything outside of the range +1 to -1; so yes -3.9 should be very "THAT'S corrosive" to plumbing. We would see some of those low levels in landfill leachate. Some of the waters used in the shield area of Canada have very low alkalinity and low pH. The LI is frequently low and much less than-1. Manhatten should be following the lead copper rules laid out for such levels. The LI level of -3.9 is a localized problem and may have many causes. Here is a report I found but have not read.

I do hope you have not been drinking this water. I suspect lead and copper would be above the regulated levels. Something that comes to suspect is a level of tuberculation and pitting in very old plumbing. The underlying surface of many tuberculated pipes is very low pH water and harbors many metals from lead, copper to arsenic.

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#6
In reply to #3

Re: High Copper Content In Domestic Water

04/20/2012 7:15 AM

Thanks for the comments. We are testing the langelier index today and are also bypassing the softner for the next month or so to increase the calcium content to help coat the piping. The temperature I believe was not taken when the sample was drawn, so it may be incorrect. We are also looking in to softening the hot water only.

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#8
In reply to #6

Re: High Copper Content In Domestic Water

04/20/2012 8:32 AM

Well, the softener is there for a purpose, and the effects of bypassing it on the downstream equipment need to be considered carefully before carrying it out.

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#11
In reply to #3

Re: High Copper Content In Domestic Water

04/20/2012 11:48 PM

There seems to be a difference of opinion on whether the Langelier Index is a good indicator of corrosivity....In any case I would be interested to know what the findings are...

http://events.nace.org/library/corrosion/NaturalWaters/corrosivity.asp

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#12
In reply to #11

Re: High Copper Content In Domestic Water

04/21/2012 12:23 AM

The Langelier Index is an empirical tool. Just like most engineering formulaic approaches and will give varying results depending on the circumstances. The whole topics of water chemistry and corrosion are complex which is why failure analysis and experience are required to solve problems when they occur.

The particular discussion thread you refer to relates to the corrosion of steel and water. This is a completely different problem than the corrosion of copper and water. Steel pipe will form a voluminous corrosion product which eventually chokes the pipes ability to carry water. The phenomenon of copper corrosion and pinhole leaks is common and widespread.

Duane

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#13
In reply to #12

Re: High Copper Content In Domestic Water

04/21/2012 10:10 AM

I don't agree that the corrosive nature of water (ie; the tendency to deposit calcium carbonates and other minerals in pipe, or not, is related to the pipe material itself.)would have a different result in copper as opposed to steel.. or anything else for that matter...

Handy calculator...

http://www.awwa.org/Resources/RTWCorrosivityCalc.cfm?navItemNumber=1576&showLogin=N

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#14
In reply to #13

Re: High Copper Content In Domestic Water

04/21/2012 4:15 PM

Many years ago when I was a registered professional engineer, I used to be a regular contributor on the NACE corrosion forum. There the engineers acted professionally and gave opinions or answers in areas and on topics that they had experience and knowledge.

I see that we have nothing to discuss Mr. SolarEagle. You have no knowledge of this topic and are acting like a troll.

Adieu.

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#16
In reply to #14

Re: High Copper Content In Domestic Water

04/21/2012 8:13 PM

I have many years of experience in water systems of all types as a troubleshooter, design, installation and maintenance...more than you could ever hope to have...That doesn't mean I know everything like you do, so I'm still willing to learn....

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#5

Re: High Copper Content In Domestic Water

04/20/2012 3:41 AM

Consider re-running the pipework in plastic instead, with those runs downstream of the water softeners starting first. Once these runs have been re-done, re-test for dissolved copper and take a view on which runs to do next, if any.

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#9

Re: High Copper Content In Domestic Water

04/20/2012 9:59 AM

Hi all...

It's been a while since I've commented on this forum.

some thoughts;

1. A secondary water treatment is a good option. I did a lot of research into the use of sodium silicate back in the late 1990's and that shows great promise in my opinion. One hospital in Vancouver used this system to treat all their water and they had no pinhole leaking problems, and some of their copper piping from the 1940's or 50's was still in use.

2. Without additional water treatment you will likely experience corrosion failures in the pipes within 10 to 15 years, or earlier in re-circulated hot water systems. So your purified water becomes a liability to the water quality where it's in direct contact with metal for extended periods of time. Drainage piping may also be affected in areas over time.

3. Brown staining is likely one of the copper oxides forming. Copper chlorides will usually show up as greenish blues, and are the result of over-chlorination. A good stable corrosion product will adhere to the inside of the copper pipe and reduce corrosion over time. These tend to be deep-black/greens (malachites). Brown corrosion product flakes away and leads to pinhole leaks.

4. Pinhole leaks into wall cavities can present a future health issue. Moulds may form and SBS may ensue.

5. Calcium build-up will present other issues so removing the water treatment for hardness is not suggested long term.

6. Replacement with PEX (I used to use Wirsbo) is an excellent idea (if you can afford the re-pipe). Consult your local plumbing and building codes for other requirements, such as firestopping, etc.

That's all for now... have to get to work!

Cheers,

Duane

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