Untreated borehole water is often unsafe to for humans to drink, at least that's usually the case here in Australia. As for cities, it depends entirely on the

Untreated borehole water is often unsafe to for humans to drink, at least that's usually the case here in Australia. As for cities, it depends entirely on the specific city. The city I grew up in was supplied by a river that was unsafe to even swim in due to agricultural runoff and high levels of heavy metals from volcanic activity. Our drinking water was so heavily chlorinated that you practically needed a water filter to make it drinkable. The city I went to university was supplied by an aquifer and modern, high quality piping. The water was such high quality, it required no treatment at all.