Distillation produces the absolute safest drinking water. In this case the liquid water is evaporated and then subsequently condensed away from the original source. This process actually physically removes the water from the impurities so it can be used safely. While this mechanism produces the cleanest water, it can also be time-consuming or expensive.

A factory distillation machine runs off of electricity and produces a steady supply of drinkable water from literally any source, to include seawater. These marvelous devices work like a champ but can set you back a thousand dollars or more. The same process can be improvised with nothing more than a sheet of plastic and some sunshine, but the yield is very low.

Dig a hole in wet ground and place a pot or cup in the center of the hole. Then cover the hole with a sheet of plastic anchored and sealed around its edges. Drop a rock in the center such that the plastic forms a cone leading down into the pot. In bright sunshine water will evaporate out of the ground and condense on the plastic before running down into the pot. The water you collect by this process is perfectly pure, but even under ideal conditions this method is a full-time job to make enough water to keep yourself alive.