No, it is very unsafe to drink tap water in Tanzania. The tap water is not considered fit for drinking purposes as they are polluted with harmful elements. We highly recommend you to use tap water only for showering or cleaning your hands, and not even for washing your fruits or vegetables. Restaurants may provide bottled water but make sure that the water is from a branded company and the seal is intact. However, branded bottled water may not be available everywhere especially when you are on a safari trip or climbing peaks. During these times, ask for treated water or boiled and filtered water. If you insist on drinking bottled water, make sure to check the seal because it may have been refilled carelessly by an unscrupulous water dealer. To evade other health issues, use either filtered or bottled water for brushing your teeth as well.