Question:
Is tap water safe for drinking without prior boiling or filtering?

Answer: There have been outbreaks of cryptosporidium in the US, particularly in Wisconsin. In Europe I have never seen the horrible white tap water that I've seen in Michigan and New York.

When I lived in NYC I had a visitor from Germany who kept saying, "But the water here looks like milk! The German people would never stand for this!"

My tap water in France looks and tastes much better than what used to come out of my taps in New York. However, if you travel to St. Petersburg in Russia one day, don't drink the water. The natives boil it and let it sit overnight before drinking it. The tap water in Barcelona used to be salty, but I don't know if that's been fixed in recent decades, as last time I was there I only drank mineral water.

*Mains* tap water is, in the UK. It has a lower bacterial count than much bottled water. However many houses have a tank in the attic which supplies cold taps in bathrooms and hot water taps, so for cooking etc usually the kitchen cold tap is direct from the mains.

In urban areas the water may be chlorine-tasting and in the highlands of Scotland it's a peaty pale brown. Still safe though.

UK Drinking Water Inspectorate http://www.dwi.gov.uk/infoleaflets.shtm