All water has bacteria and other goodies in it--no matter how it is purified, including bottled water. But in countries with good public health programs (e.g., USA, Canada, western Europe, Japan, Australian, etc.), you will be safe from any major disease.

However, as others have already pointed out, even in these countries, some people can have minor digestive system issues if they are sensitive for some reason, take drugs that reduce stomach acids, etc. That's because most purification systems aren't designed to kill every living thing in the water, and water does pick up some minor "bugs" as it travels through pipes, taps, bottling machines, etc., and then from the bottle, glass, or straw into your gullet. This is true of all water no matter the source--but most people never have a problem as their bodies easily handle these types of organisms.

The other issue is water taste, and some water does have a taste that some people don't like--this can be natural or a result of the purification system used.

I have never gotten sick from the water in Europe. We have been there about 15 times, usually for 2 or 3 weeks at a time. Your friend is mistaken.