Chemical disinfection kills viruses and bacteria. After which you safely can drink the mess yourselves. You have to use the appropriate chemicals. (Saturated iodine crystals, chlorine or silver: the latter is tasteless). A known rule: excess harms. In predicament you may temporarily help yourself with

  •   Iodine, 8 mg / liter, let affect for 30 minutes.
  •   Betadine, 7 drops / l, 30 minute. Both not for pregnant women, people with thyroid disorder or -problems.
  •   Potassium permanganate: add grains until the water is light pink. 30 minutes.
  •   Bleach : 1 drop for bright, 2 for cloudy water. Does not eliminate Giardiasis and Cryptosporidium.

bleekwaterWater is an excellent habitat for all kinds of microorganisms, including pathogenic ones.
Our tap water is pure and safe. Other water can be a risk.
Safe drinking water is not available in all countries and regions. From exotic holidays everyone knows you have to be careful, even with tap water. Apparently natives have no or very little trouble.
People who still use water from local rivers, wells etc. up from childhood got a resistance against the local fauna and flora. Their immune system is adjusted. (See also < Hygiene Hypothesis.)

If your body gets the time it can also still adjust, if you are strong enough.
Globetrotters try to build this resistance gradually. The first few days they use to brush teeth with the water, then they drink very small amounts and gradually more.
It certainly does not guarantee that you will not get tummy (traveler's diarrhea).
By the same built up resistance dogs, chickens... may, unlike us also drink from puddles etc. without necessary becoming sick.