To purify water, the distillation process uses evaporation, and water that is contaminated is heated to produce steam. When the steam cools, forming purified water, large non-volatile organic molecules and inorganic compounds (including nitrates and metals) are separated from it-along with calcium, magnesium, and certain particulates. Distillation also removes bacteria and some viruses as well.
The removal of organic compounds will vary according to the chemical characteristics of the element in question, including its boiling point and water solubility. An organic compound with a boiling point above the boiling point of water, such as some pesticides, can be removed easily. Others with a boiling point below that of water will become part of the steam, and they must be removed before distillation or they will recontaminate the water.
What Distillation Entails
Distillers, also known as stills, are composed of a boiling chamber (where the water is heated and turned into steam), a condensing chamber or coils (where the water cools and liquefies once again), and a tank where the purified water is stored. For home use, these units are kept by the kitchen faucet, and the distilled water they produce is used for cooking and drinking. They come in various sizes, are manual, partially or fully automated, and produce 3 to 11 gallons of purified water on a daily basis, Distillers can be connected to the wall, or kept on the floor or countertop. Some also come with volatile gas vents or columns to ensure that any organic chemicals with a boiling point lower than that of water will be eliminated.
Note that as the distillation process removes heavy metals, chloramines, and organic compounds, it also takes away some trace metals and oxygen that give water a pleasant taste. Consequently, some people consider the taste of purified water to be “bland” or “flat”.
Choosing a Distiller
Most distillers are made from aluminum, stainless steel, and plastic, which will not absorb the water’s impurities, and they are also easy to clean. A batch-unit distiller ranges from a one-gallon countertop unit, which is about the size of a coffee maker, to a 10-gallon floor unit. A continuous-flow unit is connected to the owner’s water-supply line, constantly produces more distilled water, and removes all impurities periodically.