What @rupert said.
I travelled for years and targeted out of the way places - drinking any water was risky and bottled water was never an option.
Use bleach. Cheap, safe and super effective
Only use regular, unscented chlorine bleach that is suitable for disinfection and sanitization as indicated on the label. The label may say that the active ingredient is 6 or 8.25% of sodium hypochlorite.
Do not use scented, color safe, or bleaches with added cleaners. If you can, if the water is dirty / cloudy, let it settle and also filter it through a clean cloth, paper towel etc.
Bookmarks