OMG I dont meen to be rude but i am like laughing pretty darn hard right now. Really? None of you "City Folk" have never used a well before? Here in the remote place know as Traverse City (in michigan its not that small) pretty much everyone uses well water. It is true that well water is extremely hard or otherwise called "liquid rock" but that all depends on where you live. I know in places such as Hawaii the ground water is very soft due to the volcanic nature of the islands. I know for sure that anywhere near the great lakes you will get very hard water due to the limestone below. So, once again, it all depends on where you live.
As far as the disease goes, I would not know. I have never lived in an urban area but I would guess it to be clean of diseases such as e. coli for the ground would filter the water of those types of things. I do now know where you live but another thing to worry about if you live in an urban area would be pollutants in the water such as lead. If you are intending to use this water for your own drinking or for your pets I would get your water tested, which is fairly easy. They sell test kits online or you could get it tested in many places or by people such as the person who takes care of your water.