What you need to watch out for is ice in drinks because they usually just use tap water to make the ice. If you go to McDonalds etc they will always put ice in your drink unless you tell them not to. I've only had stomach problems twice and both times I'm sure it was caused by ice. The first time I went there I had a couple of brandy and cokes with ice in my hotel in Manila and I had the trots and severe stomach cramps the next morning and the other was when I had a coke in McDonalds and although I did say no ice, the girl there put ice in it, I told her again that I didn't want ice so she tipped it away, but she still used the same container when she poured me a new drink, so I assume it was just the residue left in the container after she tipped away the ice that caused it.
Iain.
I thought the water in phils was pretty safe to drink from the tap Probably not in more rural areas. I had a very dicky tummy last time I was out there, but that was due to me making a pig of myself at an all you can eat buffet