Just about the first thing we do after picking up a rental car in france is hit a supermarket and get a six-pack of large-size bottled water and a cooler chest to keep it in. We've found that sticking with bottled water throughout our stay prevents stomach upsets. We especially like Evian and Plancoét (when we can find the latter; it's from Brittany), although in France we make a bee-line for Malvern Water. (That's what the Queen takes with her when traveling abroad.)

Romania is the only place in Europe where we have confined ourselves to bottled water, and that is because they do not have an up to date water purification system. We too just re-fil the bottles we have with us from the tap. Personally, I think bottled water is one of the biggest rip-offs there is.

I'm not sure why supermarket bottled water (low prices) is a rip-off. We drink it at home too because our local water tastes awful.

Solutions.
1.- Buy water at supermarkets.
2.- Buy a brita travel bottle filter
(http://www.brita.com/202i.html)

Rome has the best public drinking water..You can refill your bottles from the various fountains around the city..The water is icy cold, it comes through the Ancient Romans acqueducts..

Totally agree with nytraveler!
When I was at Bethesda NH in the early 70's we treated all US State Dept, etc. folks returning from St Petersburg for Giardiasis without wasting time and money to confirm the DX - nothing has changed there.
However, my former partner acquired the absolute worst case of Giardia I have ever seen right here in Dallas.
M (MD ABIM,ABNM,ABR)

It took me a few trips to Italy to muster up the nerve to drink right from
the public drinking fountains and when I did I was so glad, it was wonderful!

The first time it is a little odd to stick your mouth up to some statue (female, male or animal) and drink from one of it's orifices in a fountain, but after a while we filled up water bottles from them too.

Like kismetchimera wrote, it is delicious and icy cold from the acqueducts, try it.

Cool. Thanks everyone. Today, I headed out to get a Brita Fill & Go water bottle (didn't know they make travel size bottles -- thanks sol_veracruzano). It filters out minerals, that's what I need. And it's pretty handy too.

I just read about this church in Rome: Santa Maria in Via. It has a spring underneath the church and the water is supposed to be "healing." Can't wait to try it. I'm sure I won't need my Fill & Go for that! Now I'd try water from the public fountains since you're all in favor of it.

I don't react well to the tap water in California either, but the water in France, Italy, Germany, England and Switzerland has not bothered me.

I think they add something strange to CA water. BTW, this happened before Arnold too.

I'll drink tap water from most places in Europe that we've been to...but I try to avoid outdoor drinking fountains. A little disconcerting when you see how popular they are with pigeons.