Water purity for KNF solutions

Water is important, just behind air and sunlight in terms of how much it matters. The main thing with pond and river water is that it is not stagnant, and your nose will know if it smells putrid or gross. Typically flowing water is preferred, because as it flows, oxygen is brought into the water which will reduce pathogens, but also pond water tends to be full of Purple Non-sulfur Bacteria which produce oxygen and will again reduce pathogens. Purple Bacteria are also useful in KNF context.

Main thing is the water is not stinky. If it is, aerating it through stirring, vortexing or bubbling for several hours can tremendously improve the condition of the water and make the water more conducive to the type of biology that we want to cultivate in KNF.