Well here's a for instance:
In Florida my horses were ok drinkers. Just ok drinkers. Normal I'd say. The well water down there was disgusting and stunk like rotten eggs. Loaded with sulphur and I dont' know what else but it sure stank.
Upon moving to Tennessee, the well water up here was loaded with iron and I mean loaded with it. It is so bad that all my water buckets and troffs turned orange inside dispite me scrubbing them with clorox on a regular basis. However I couldn't believe how these horses gulped it up by the gallons at first. I guess compared to what they had in Florida, they love this stuff a lot. Then they got used to it and went back to drinking "just ok"
Enter city water now. When we built the new barn, Jerry hooked up the city water to it so no more orange rusty stained buckets. They are drinking that up amazingly well.
Recently, I got a notice from our city water suppier to tell me that the water has been contaminated now for the past month and suggest we all used bottle water or boil it, but they are working on getting it back under control. Gee, that's lovely. How thoughtful of them! This is not the first time this has happened either.
Good luck!