Searching water is no problem. But finding it sometimes is...

To find water go in the direction of willow and alder.
Find the lowest point in the landscape. Dig there if necessary.
Follow grazing animals. Also finches and pigeons, especially at sunrise and sunset.
Notice insects: mosquitoes and gnats. Bees stay to approximate 6.5 km nearby water.
Look in holes and clefts, especially when they appear to be greener than the surrounding area.

Obvious: close to the water source the water is cleaner than further away.

oppervlaktewaterA groundwater well contains water that has been filtered by the surrounding soil. I still regularly drank it in the early’60’s. Unbeatable tasty and fresh on hot summer days: a stone-cold bucket of crystal clear water! With nowadays phosphate-, nitrate- and other pollutions I would not dare to drink it without recent certification. Unfortunately, we have done this to ourselves. I did not realize then what a luxury that water was.

To filter pond water you can dig a hole on a short distance (1 m) of the lake. Spoon the first, still dirty water out until you get clear water. Filter it and cook it at least 1 minute.

Rainwater is, if you can catch without polluting it, rather safe to drink. It is distilled by the water cycle of Mother Earth. (Unfortunately our heating, transport and industry spray too many mess to heaven.)