Tap water here in the UK is probably safer than bottled water, the big exception was tragedy in the 90's in a town in Cumbria called Camelford where the water company dumped/miss applied 20 tons of aluminium sulphate into the drinking water. This led to permanent brain damage in quite a few people..Streams and rivers around here? not a chance without purifying.
People used to drink from rivers with dead animals upstream and were fine. Now we have water on tap, tested and purified and we worry about it, buying bottled water because we think it is better.Too much money around the western world.