Test for stray current in plumbing system

[bernd]

Hi all,

I suspect a stray current in a plumbing system to be the root cause of elevated copper levels in the water.

I would highly appreciate any guidance/best practices on how/where to best test for stray currents in a plumbing system (e.g., measure currents against neutral/ground of the closest outlet).

Thank you very much,


-Bernd

 

[Dzboyce]

I’d be more concerned about checking the ph level of the water itself. Normally that is what causes copper or lead leaching.

 

[MTW]

Electrolysis of copper plumbing due to electrical currents, is normally done by DC current. AC current has no effect.

Is there any DC sources in your neighboring area or buildings, it can travel on underground utility piping, including gas lines.

You can try to measure DC voltage on your water service line right where it enters the building. Disconnect the grounding electrode conductor from the water pipe bonding clamp, and measure for DC volts between the pipe and the electrode conductor.

Back in the 20's and 30's this was prevalent from DC powered trolleys in the area and often called blue water.

If you have this going on, you might experience leaks and malfunctions of piping connections and valving.

Further Reading.
https://www.copper.org/applications/plumbing/techcorner/staining_bathroom_fixtures.html

https://www.copper.org/applications/plumbing/techcorner/electrolysis_cause_copper_tube_fail.html

 

[Mystic Pools]

There is documentation of this affecting swimming pool water from stray currents at neighboring properties underground service.

Difficulties with balancing and maintaining the water chemistry. And if the water was in an acidic condition, i.e., low pH or low total alkalinity, it reeked havoc on the water.
Metallic parts on the pool would corrode.

Then there's the bather swimming in this environment.........

 

[roger]

I’d be more concerned about checking the ph level of the water itself. Normally that is what causes copper or lead leaching.

And I agree and know from personal experience with acidic water in copper piping in my own home.

Roger

 

[tom baker]

I can say with certainly your issue is not related to grounding. This question has come up enough it should be elevated to a myth status.
Copper and lead corrosion is caused by low pH water. In Flint, the water source was changed and corrosion control was not put in place.
Low pH water is aggressive and erodes the protecive oxide film.
Where I work we adjust the pH of our water from 7.5/8.0 to 8.5 by adding a very small amount of caustic soda.
And as pointed out, corrosion is caused by DC current, not AC.
What I would suggest is to contract your water supplier and ask what the pH of the water is. If you customer is on a private system then you may be on your own, but there are probably some small treatment systems available
https://www.epa.gov/dwreginfo/lead-and-copper-rule

Water suppliers are required to provide a consumer confidence report https://www.epa.gov/ccr

Our corrosion control has been in place since 1999 and follow up testing has proved it effectiveness

 

[bernd]

Thank you very much, everybody. That's very helpful.

The consumer confidence report is, in fact, available from the customer's water company. The pH level is 7.3-7.6 (7.5 on average), and total alkalinity is 240-330 CaCO3 (300 on average).
http://lacumbrewater.com/docs/CCR_2017_report(legal).pdf

So far, the customer tried to inject food-grade phosphate into the water to support and accelerate the build-up of a protective layer. The house was built 2-3 years ago. However, this approach wasn't successful.

Where I work we adjust the pH of our water from 7.5/8.0 to 8.5 by adding a very small amount of caustic soda.

I'm surprised that you are adjusting pH levels of 7.5/8.0, since "solutions with a pH less than 7 are said to be acidic."

A proportional injection system feeding a precise amount of sodium carbonate might be worth a try...

Our corrosion control has been in place since 1999 and follow up testing has proved it effectiveness.

That's very encouraging.

Thanks again,


-Bernd

 

[GoldDigger]

I'm surprised that you are adjusting pH levels of 7.5/8.0, since "solutions with a pH less than 7 are said to be acidic."

A proportional injection system feeding a precise amount of sodium carbonate might be worth a try...

Are you asking why such a high pH target is selected?
Acidic water corrodes the oxide film. If the pH is lower than 7 you have a potential problem. It might seem logical to target a pH of exactly 7.0, but since the incoming pH from the water company may vary seasonally or daily depending on their mix of water sources it makes sense to overshoot a little and maintain on the average a slightly basic (up to 8.0) target pH.
If instead of a simple open loop proportional injection system you used sensors to dynamically adjust the injection, you could set a target closer to 7.0 exactly.

 

[tom baker]

20 years of use and followup testing have shown our target value works. Keep in mind this is for a large water system, average demand is 6 million gallons a day, and the corrosion treatment is at the entrance to the distribution system. We also chlorinate our well water, the hypo (bleach at 12.5 %) used has a good amount of caustic which also raises the pH.
The effectiveness is tested by measuring pH throughout the system.
We use caustic soda , typical feed rate is 2.5 gallons per hour or 62 gallons per day into 6 million gallons, kind of a dribble really, but it works.
7.5 from the consumer confidence report seems low...are there other customers with the same issue?

 

[Mystic Pools]

The consumer confidence report is, in fact, available from the customer's water company. The pH level is 7.3-7.6 (7.5 on average), and total alkalinity is 240-330 CaCO3 (300 on average).
http://lacumbrewater.com/docs/CCR_20...ort(legal).pdf

In the swimming pool world, the total alkalinity suggested range is 80-120 ppm. Anything above is considered scale forming.

No mention of calcium hardness here. For pools, range is 250-400 ppm. As with TA, high levels create scale. Just check faucet aerators and your pots after boiling water.
The white crust is scale and it can build up in copper plumbing.

In my house, I installed a water treatment system to reduce calcium hardness and get rid of sulfur (shallow well water) and iron. I also installed a water softening system.
Big difference with regarding scale issues and iron stains-no more