The well being unused could be part of the problem. In '99 I bought a homestead that hadn't been lived on for 20 years or so. When I dropped a pump in the well to check it, the water was literally black and stunk horribly of hydrogen sulfide (the black was probably oxidized manganese, of which the water contains a lot). After running hundreds of gallons down the hill, the water cleared up completely, but still smelled and tasted somewhat of hydrogen sulfide (still does directly out of the well).
In my case, because the well is low-producing, I put a holding tank in to supply the house I built. I didn't know it at the time, but the aeration from the water being sprayed into the side of the top of the tank helped remove all of the hydrogen sulfide, so I've never had any in my domestic water. If possible, a holding tank is probably the easiest way to completely get rid of the hydrogen sulfide in the water. The magnesium in the hot water anode may act like the manganese in my water. If that's the case, yeah, it would make a pretty nasty combination.
Edit to add: Last week I was staying at someone's house that had a lot of Hydrogen Sulfide in the water to the point that they only drink bottled water. I don't care that much about it, so I'd drink right out of the hose in the yard if that's where I was. I noticed that the water sitting the hose wouldn't taste of H2S; I'd only notice it if I drank until I was getting water out of the spigot. Apparently even sitting in an open hose overnight is enough to outgas the H2S.
Last edited by Thegman; 07/22/19.
