Domestic Hot Water and Legionnaires

I had a thought!
Perhaps for those who would like to take some time to research this-----It's the metal ions that supposedly keep the bacteria at bay, right? Perhaps a zinc sacrificial anode could do the same job. I say this because either zinc flashing or copper flashing on a roof both keep all that nasty stuff from growing downstream on asphalt shingles. Or perhaps an anode made of copper. I'm sure it's the copper sulphate that is killing the bacteria on the roof. Don't know about the zinc. I don't believe the whole hot water system needs to be be plumbed in copper.

velvetfoot said:

There was that lead solder thing.

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Yeah, more than 50 years ago, and vastly overstated. There were serious problems with lead pipe, and lead solder was eventually eliminated in response, but it was never really determined that the small amount of lead leaching from small amounts of exposed solder was causing health problems. Not a bad thing... but again, ancient past. Copper plumbing with zero-lead solders have been used for a very long time, with a very good track record, in terms of human health.

Fred61 said:

Don't know about the zinc. I don't believe the whole hot water system needs to be be plumbed in copper.

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Yeah, but aside from a fairly insignificant cost difference, with respect to the cost of building a house, what's the down side to using all copper? The only cases I know of premature failure are all related to severe and uncommon water (particulate and pH) condition problems, which should likely be addressed if you're consuming said water.

All this talk has been about tank type hot water tanks. What about tankless on demand heaters? I have my rinnai tankless set at 120 deg.
Is that bad? I could set it higher but works great at 120. Any thoughts?

The issue is more related to tanks that can sit unused for a while at room temperature to something under 140F.
Tankless heaters are usually copper or copper alloys. The potential issue is much lower.

tom in maine said:

If you research plumbing with plastic, you find a lot on the bioslime that grows on the inside of plastic domestic water tubing.
This does not occur in copper. My suspicion is that copper and materials containing copper deter this growth.

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That's why they make copper bottom paint for boats... kills biological growth.

Back at my old place I had a 1/4 acre pond that would grow some sort of slime and cloud up the water. I treated it with copper sulfate crystals by placing a cupful of the material in an old sock, tying a line to it and tossing out to the middle of the pond and reeling it back in full circle around the pond until the material was totally dissolved. Within 24 hours the water was clear. and the dead organism was laying on the bottom.