in rio de janeiro unfiltered tap water is not recommeded for drinking and can, after time, cause adverse stomach reactions - in a small percentage of people, even using tap water to brush teeth can cause belly issues and needs time getting used to - locals generally drink filtered water or buy bottled water.

during the hottest months, november through march, it is preferable to buy bottled water in drugstores or supermarkets rather than in the street or on the beach - some of the bottled water sold randomly on the beach is actually carefully packaged tap water -  many drugstores sell more trustworthy bottled water, and certain locations sell 5 gallon containers which can be visulized here.

when purchasing water individuals should check if the water contains bubbles, gas, since this drink is just as common as natural mineral water - a common question at restaurants is whether or not individuals prefer water with gas, 'com gas' or without gas 'sem gas.'