[mantas]

Of course it varies around the world, but in my whereabouts there're few rules-of-thumb regarding such springs:

- some popular springs are tested by gov/parks regularly and even have results sheet attached

- knowingly bad springs are marked. Maybe as simple as "do not drink" on a sheet of paper in a plastic bag.

- most good springs are prepared. At least home-made step to come without walking in the water/mud, cup to drink from etc. If spring is regularly used by locals - what to worry?

If spring doesn't match any of these - use your judgement. Moving water is good. Stale water is risky. Settlement upstream or on the hill - risky. Farm - very risky!

Boiling is good. Another good idea is hiking bottles with water filters. They do affect taste more than boiling though. I think they're usually carbon-based and/or UV?