Do not drink water from the tap. Try not to take ice and ice cubes, no fruit juices mixed with water and no food prepared with tap water. You can buy bottled water almost everywhere. If you buy a bottle of water, check if the bottle is sealed.
Explore Tanzania puts a lot of effort into limiting the amount of plastic that enters the parks (mainly bottles of mineral water). To limit our waste, we have made agreements with a mineral water company.
In your safari jeep (in the north of Tanzania) is a container with 20 liters of mineral water. You get a bottle you can fill. In our Green Camps there is also a container with clean mineral water in the restaurant tent.