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?

I once drank lake water in Iceland during winter. The only reason I could be convinced to do so was because it was Iceland during the winter. It was absolutely fantastic. Easily the best tasting water I've had by an order of magnitude.

I once drank water from a natural spring in Kolomenskoye Park in the middle of Moscow. Tasted great with no ill effects. Don't know if it's safe for chronic consumption though.

95% it is safe. If it wasn't, it'd be marked as such. The spring doesn't need much space. Rain drops, gets filtered by sand and soil, comes out from a spring down bellow. A park of few hundred square meters is more than enough to be a safe filter.

Source: drink frequently from springs in/around towns.

I once drank a bottle of lake water straight from the lake, way out in the wilderness in northern Ontario. No negative effects. I don't remember the water tasting particularly good or bad.

Ugh. Don't do that. The water is disgusting in Ontario. There are some pretty strong guidelines regarding eating fish from there too. Heard stories from people who need to test it and filter it for injectables. It's not out in the wilderness, but it's still a good idea to just avoid it. So you drank one bottle that's different from sustained consumption.

Does boiling destroy taste?

My strategy was to wait a day or two and see if my buddy got sick before I tried it. But, yeah, after seeing the other comment here, boiling probably would have been a good idea!

Most likely yes. Boiling brings the water closer to purified water.