Sometimes I have to buy drinking and cooking water, but I try not to due to the cost factor on a low income.
If you are drinking from a stream, make sure you know what is upstream. Don't drink where there are mining operations or dredging of old gold mining sites (mercury in the water), upstream. If you do drink water from a stream take the water from the fastest moving area not still water as bacteria rarely grows in a moving stream. Keep that in mind with your own internal system and keep it flushed with at least 2 liters of water (more if hot or exercising) per day.
Don't be caught out travelling without enough water with you. If you have to buy water as you cross the Nullabour Plains then expect to pay more for water than you pay for fuel for your car.
The main thing though is to plan in advance when traveling though varied water quality areas. I use a two minute rolling boil when uncertain of tap water safety in some places and never kid myself that tank water is fit to drink straight from the tank
Another good reason to drink plenty of water when traveling and maybe being exposed to more pathogens in public conveniences than you come up against at home, is that regular flushing of the urinary tract helps prevent bacteria breeding and reduces incidences of UTI's