Steam distillers are one of the oldest and one of the most effective ways to purify drinking water. Steam distillation utilizes a very simple process that mimics the natural processes that purify the water on the Earth. On earth, this process is called the hydrologic cycle. The hydrologic cycle is a process of events where water moves through the on and through the Earth and atmosphere in its liquid and vapor forms. This process is powered exclusively by the energy of the sun.

The hydrologic cycle begins with the water that exists on the surface of the earth. This includes water in soil, rivers, lakes, streams, oceans and on every other surface you can imagine. Sunlight strikes the water and energizes some of the water molecules enough to turn them from liquid to vapor. This process is often referred to as evaporation. Since the water vapor is warmer than the water it came from, it rises and enters the atmosphere. In order to understand how this process purifies water, it's important to understand that only pure water is light enough to be vaporized. As water turns from liquid to vapor it releases it's impurities. The now pure water rises up higher into the atmosphere and in doing so becomes cooler and cooler. It combines with other vaporized water molecules to become microscopic droplets. Droplets combine to form what we know as clouds. The droplets continue to condense with other droplets and grow in mass until the droplets can no longer be suspended in the air. This is when it rains. It should be noted that rain is very pure when it first forms, but picks up contaminants as is falls through the Earth's atmosphere.

So, in nature it is the process is vaporization and condensation which leads to the formation of pure water. A steam distiller operates in virtually the same way. First, the reservoir of the distiller is filled with tap water. The water is then heated until it boils. Steam (aka water vapor) then rises out of the boiler and enters a condensation loop. Remember, as with the hydrologic cycle, when water vaporizes it leaves behind all of its contaminants. In the condensation loop there is a spiral of stainless steel that is cooled by air with a fan. As steam contacts the sides of the cooling loop it condenses and trickles down towards the spout.

It's at this point that a steam distiller varies slightly from the natural hydrological process. Some contaminants in water have the same boiling point and condensing properties as the water itself. That means that they are able to travel through the distiller with the water and could end up in the purified water. For this reason, most high quality steam distillers include a carbon filter cup that acts as a final purification stage, before the water is dispensed into the collection cup. The activated carbon filter cup removes any remaining contaminants leaving only pure, clean, healthy water.

When shopping for a steam distiller look for products that utilize high grade stainless steel in the boiler and condensing coil and of course, look for products that are supported by a manufacturer's warranty.