Ultraviolet water filtration is a very effective way to disinfect drinking water. It works pretty much the same way as in nature itself; UV light of enough strength will harm bacterial and viral DNA, it will disrupt the organisms reproduction ability and they will become harmless to humans.

By exposing water to ultraviolet light of a certain wavelength (253.7 nm), all microorganisms will be disabled. This can be used for water purification purposes where the problem is any of bacteria, virus or other similar contaminants.

The chemistry of the drinking water is not affected, it is a bit like boiling water. It is an environmentally friendly method, used in the US since the 1930's.

Ultraviolet lamps for water filter use

The 253.7 nm UV light is normally generated from mercury low pressure lamps.

Modern UV technology has resulted in development of highly specialized ultraviolet lamps which generate both 185 nm and 253.7 nm UV light. This combination is necessary for photooxidation of organic compounds. With this new technology it is now possible to keep the TOC (total organic carbon) level as low as 4-6 parts per billion.

Prefiltration as part of a water purification system

The disadvantage of using ultraviolet light for water purification is that it will not remove particles, ions or colloids. It is however possible to combine ultraviolet water filtration with other techniques to get an optimum result.

By adding prefilters, especially designed for the removal of contaminants in the feed water, many of the shortages of ultraviolet water filtration can be improved upon. Typical prefilters are - activated carbon water filters, particulate filters (removing sediment) and/or different softening agents to remove the minerals causing hard water.