Quote Originally Posted by quejai View Post
Demineralised water is more pure than rainwater is more pure than tapwater.

If you live in an urban environment, it's closer to tapwater from absorbing carbon dioxide (turns it to weak carbonic acid) and etc from pollution in the air.
If you live in a rural place, it's much closer to demineralised water.

Either way, wait out the first 10 minutes or so of rain to 'wash out' the air, and then collect water after that. It's the cleanest you're going to get.
OK, so my father was kind of right, because we lived on a farm in a rural area, 150KM away from the closest city.

But for me....OK, I suppose I would also then need to consider filtration, which in the end might just end up being just as easy to buy the 4 litre bottles from the super market.