: My acidic (PH6.7) well water corrodes my water heater. I get about 6-7 years each. Copper plumbing. I installed dielectric unions. Before I hooked up the gas and the stack, I took a voltmeter and measured 0.4volts DC across the union! I have created a battery!!! When I hooked up the gas line, which of course was grounded, the voltage dropped to zero because, in effect, I shorted the battery. I put a dielectric union on the gas line and insulated the stack. I'm hoping I can get more life out of the water heater. I can't prevent it from being a bettery without expensive water treatment, but I can prevent the battery from being shorted. Shorted batteries corrode fast. Does this make sense?

What? Just reading this is making my brain hurt. Now I wish I knew more about the electrical effects on corroding water heaters.

Water lines are required to be grounded in a plumbing system, in case an electrical wire comes in contact with a pipe. Plumbers have been killed because of this. A person should be careful with dielectric unions and make sure the grounding is in place.
Regards,
Terry