Local public health departments and some independent labs will test water for bacterial and chemical contamination and pronounce the source potable(or not).

Might be sensible to test your swimming pool water, water from your sump pump, and water from the nearest stream in preparation for use as a backup water source. In my experience, pools collect a lot of nastiness from the environment: bird poop, rodents, reptiles, dogs, cattle, acid rain, engine exhaust particulates, deodorant, sun screen...it is considerably easier to remove the bacteria than to remove the cows.That said, most of the rest of the world depends on water sources much more questionable than the pool.

After the cow fell in, we built a better fence.