Why can animals drink untreated water?

Answer 1

yes, animals have been exposed to much more germs than we have, therefore they have more stronger immune system.
in developing countries, people drink untrerated water whereas we might get sick from drinking the same water

also, animals have a stronger innate immune system, for example dogs have more powerful germ degrading enzymes in their saliva than we have in ours. another example is that cats have a slightly higher body temperature, which restricts growth of some human pathogens, which prefer our body temperature.

Answer 2

hehe, ya, they might be a little more up to the task since they're eating stuff off the ground since they're little. So one factor is they get a more built-up immune system. BUT- they also get a lot more infections than we do, we just assume they don't (that's why your pets are supposed to be periodically "de-wormed" by the vet every few years). Vets also don't worry nearly as much about giving them medications with a safety level that would be considered "risky" or "unknown" to humans. They also have shorter life-spans (well, most of 'em do), and can't explain their personal health problems to us, so we don't perceive everything that's really going on inside.

Answer 3

Their digestive system can destroy pathogenic bacteria. However, poisonous water can kill all customers.