In Brazilian cities are the water treated and it is advisable to not drink it directly from the tap. It is recommended to buy and drink bottled mineral water, avoid buying food stuff from street vendors, preferable with gas/carbonated. Do not drink beverages with ice made from tap water. Make sure that the fresh you eat is peeled or cleaned. Do the same with vegetables, check that they are well cleaned, or even better, cooked. Take care with seafood (particularly in cold seafood salads) must be fresh and well cooked. People with reduced immunity should avoid poorly fried meet and ice cream. If you are in an exclusive restaurants you may not worry so much about these advices.