Copper in Hot water but none in Cold Water

[DHH]

I have had approximately 1.4 PPM of copper in the hot water only, absolutely 0 PPM in the cold water for the past couple of years. Copper is just enough to slowly turn blonde hair slightly green. I have a well with a water softener and a circulation pump which runs 12hrs/day. PVC pipe into the house, copper pipe for hot and cold water which runs under the slab to all devices. House is 20+/- years old.
There are no dissimilar metals anywhere on the lines, everything is copper, new gas water heater with dielectric nipples.
Have tried turning off softener, circulation pump for over 2 months with no effect.
We have:
Very Hard water - 780PPM or 45gpg
No iron
PH 7.0
High TDS - 1500 PPM
Sediment filter on the well water.
I work in the construction industry and have spoken to engineers and commercial plumbers with no luck.

Anyone got any ideas??

 

[WorthFlorida]

No idea myself. Do you have a test kit or send samples to a lab? I'm assuming there isn't a blending tank for chlorine disinfectant. Is the recirculated on a dedicated return line or cold water pipe as the return?

I would take a water sample right before the cold water enters the WH, right after the WH, then at sinks and tub/showers. When one pops up with a high copper number it should narrow it down.

 

[Sponsor]

 

[DHH]

No idea myself. Do you have a test kit or send samples to a lab? I'm assuming there isn't a blending tank for chlorine disinfectant. Is the recirculated on a dedicated return line or cold water pipe as the return?

I would take a water sample right before the cold water enters the WH, right after the WH, then at sinks and tub/showers. When one pops up with a high copper number it should narrow it down.

No blending tank. Dedictated return line. Tested at every faucet-all the same. Incoming water is 0 ppm. all cold faucets are also 0 ppm.

 

[WorthFlorida]

My techniques for trouble shooting is usually eliminate items to narrow down. To help prove or disprove the copper is leaching from the pipes with heated water. Shut the power or gas off at the water heater and drain the tank, turn off the circulator. Refill it with cold water and do not power up the water heater so only cold water will run from the hot water tap at the faucets.

If the copper is zero, then hot water is leaching copper from the pipes, or (doubtful) the anode rod is reacting to sometime in the water and while the water sits and being heated, it has time to react. I would place a spigot right after the water heater to take any samples.

It might be worth it to have a full water analysis on the cold side and bring the results to your local co-operative extension. They are usually an extension to one of the state universities and have great resources. Someone may know a chemical engineer that could help. There is the Texas Water Resource Institue, thought they usually manage water sources and agriculture use, it might be worth to asked there.

If you have a neightbor with copper pipes and a well, ask to get a sample from their home. No one else may not notice it if there are no blonds.

 

[Reach4]

I would re-check pH. I like the cheap pH meters (mine is yellow) where you dip the meter tip into a calibration solution each time, and adjust the calibration screw if needed.

 

[FraserJim]

I would be interested to see if it is ground currents circulating through the copper pipes. Extremely difficult to troubleshot, so the approach is to ensure that all components are properly bonded.

Ground currents are always present when you have two independent grounds to earth, and you link the grounds through a conductor. You break the continuity of your copper pipes when you use dielectric fittings at your water heater. So, an opportunity for another ground to earth.

Commercial buildings develop building grounds (called ufer) by encasing bare copper wire in concrete, so you may have additional grounds to earth when your copper comes into contact with your slab.

Where and how does the PVC transition to copper? Do you have a driven ground rod for the home and is it bonded with a clean solid connection to your copper cold water pipe and to your main electrical panel?

First, check your ground rod connections and bonds to your cold water pipe.

At this point, if you don't already have one, I would install a hot water heater bonding jumper between the cold and hot copper. Available in kits at hardware stores. Also install one around water softener, and any other components that may break the copper. I am presuming that you don't have a meter? If things change, for better or worse, I would jumper, between hot and cold, all plumbing fixtures that are accessible.

One last question, where are you measuring and are concentration higher at some points?

Good luck! Keep us posted.