Water
Within the larger cities mains water is normally chlorinated, and whilst relatively safe may cause mild abdominal upsets. Drinking water outside main cities and towns is likely to be contaminated and sterilisation is considered essential. We would not recommend that you drink tap water anywhere in Tanzania. Bottled water is available and you should use this, even to brush your teeth. Sterilised water, using puri-tabs or boiling is an alternative. Always make sure that bottled water comes from a sealed bottle and has not simply been taken from the tap – if the little plastic seal around the bottom of the cap isn’t intact don’t buy it.
The other side of this question is the need to drink water – you should be drinking lots of it, at least a couple of litres a day.