With increasing concerns about contaminants in water that may affect health, distillation can remove contaminates from drinking water.
Distillation is an effective method for removing most contaminates
According to the U.S. Environmental Protection Agency: “Distillation is an effective water treatment technology for commercial and household use. When water is purified by distillation, it is boiled in a container and the steam is sent into cooling tubes. The steam is condensed and then collected as purified water in a second container. The impurities in the water are left behind in the first container and can be discarded. The distillation process removes almost all impurities from water. Distillers are commonly used for removing nitrates, bacteria, sodium, hardness, dissolved solids, most organic compounds, and lead. Contaminants that easily turn into gases, such as gasoline components or radon, may remain in the water unless the system is specifically designed to remove them. Distilled water may taste flat to some people because the water’s natural minerals and dissolved oxygen often have been removed.”
Contaminants Removed from Water by Distillation
Distillation can remove most impurities from water. Compounds removed include sodium, hardness compounds such as calcium and magnesium, other dissolved solids including iron and manganese, fluoride, and nitrate. Distillation effectively inactivates microorganisms such as bacteria, viruses, and protozoan cysts. Distillation can also remove many organic compounds and heavy metals.
Contaminants Not Removed from Water by Distillation
Depending on the contaminates, a combination of treatment processes may be required to effectively treat the water. Certain pesticides, volatile solvents, and volatile organic compounds with boiling points close to or below that of water will vaporize along with the water as it is boiled in the distiller. These compounds will not be completely removed unless another process is used prior to condensation.
Treatment Principles
Distillers use heat to boil contaminated water and produce steam. Impurities such as inorganic compounds and large non-volatile organic compounds are not vaporized and are left behind in the boiling chamber. The heat inactivates bacteria, viruses, and protozoan cysts. The steam rises and enters a cooling section. When the steam cools, it condenses back to a liquid. The resulting water can have up to 99.5 percent of impurities removed. The water remaining in the boiling chamber has a much higher concentration of impurities and should be discarded.
Since volatile organic compounds can also vaporize as the water is boiled and turned to steam, methods for removing them can be incorporated into the system. Distillers that use a combination of removal methods are more efficient than those with a single method. section
Incorporating gas vents (small holes in the passage leading to the condensing coils) can allow volatile organic compounds to escape before entering the cooling section.
Another option is to use an activated carbon filter to remove volatile organic compounds from the condensed water before they enter the storage tank.
In and emergency, a simple distiller can be made using a pot and stove or a pot and solar energy. See “Distill Water Using a Pot and Stove” and “Solar Desalination for Drinking Water.”
In summary, distillation can remove contaminates from drinking water and is an effective solution in emergency situations.
