Bottled water is a good idea. You can bring a Katadyn filter or an ultra violet sterilizer like the Steripen if you want. Bottled water is available at all the small stores and gas stations but it can be a bit pricey for the brand names that are shipped in. We don't provide plastic bottles anymore because there is no viable plastic recycling plan here. Instead, we use 5 gal. bottles from the local water purification plant. We provide guests with carafes of water. I brush my teeth with tap water and drink it sometimes without problems. My advice is to start eating yogurt daily and your intestinal flora and fauna will be up to the task of protecting you form any bad effects. If you eat salad, it will have been washed in tap water.
Oh, and throw some immodium in your tank bag just in case