Quick clean water
If you are in desperate need of water, or can't boil your water you can find a river. Rivers that flow slowly are usually filled with animal feces and bacteria that can give you nasty diarhea. I learned this from the show man vs wild. You can dig a trench about 6 in to 1 ft away from the river bank.
Try to make it a bit higher than the water. Dig a hole until it is below water level. The dirt and rocks will filter the water of some nasty bacteria as it passes through.
The water in the hole you made is fine to drink. Use this only if you have to.