I often just go for the tap water, but when you look out the window and see your guesthouse’s water pump dipping into the mekong, it just doesn’t seem like a good idea.

And yes, I have a money belt, actually a neck thingy, but it lives in my bag, not on me.

In lieu of a water filter, I traveled through Asia with a UV water purifier, which was small, useful, and saved me from further filling landfills with bottled water, as well as saving me about $150 in bottled water costs over 6 weeks. (http://theprofessionalhobo.com/2008/06/clean-water-in-asia-and-not-from-a-bottle/)
As for the bulky water filter itself, I agree: unless you are planning to be in the deep back-country somewhere that you will need to filter out non-clear water, most of the time you can get away with buying or purifying it.

I like the moneybelt, but you have to be smart about it. I use a moneybelt with (a) Passport, (b) Paper tickets if I have them, (c) Cash. It’s thin enough to blend with my beer belly. I also NEVER access it in public. Money comes out once or twice a week and goes in my wallet, I get my tickets and passports out the morning we fly. The moneybelt isn’t the problem: dumb usage is the problem.

I dislike the money belt as well. I remember the first time I used it when I went to the UK in 1997. It was so cumbersome. Plus, people SEE you take the money belt out…it defeats the purpose of keeping your money & passport safe.