Same problem here. My parents' cottage house is about 150m from a river, so underground water is abundant. A neighbor's well, 3m in depth, gives pure clean water. Their own two wells, 40 and 15m, both yield undrinkable water with iron and sulfur as well.

Concerning rainwater, don't know if it's somehow related to the territory you live on (and I reckon it's not, since clouds travel all round the Earth), but I was raised in fear of acid-rains. Chernobyl is way to close, unfortunately.

When it stroke in April '86, Soviet government refused to tell anybody what happened. Five days later it was a traditional May's demonstration, with thousands of people on the streets. A lot of people were irradiated, because a rain poured on this day. In later years, of course radiation wasn't an issue, but people grew too much concerned about rainwater.