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Water Facts

UV water filtration is excellent to treat water sources, rain water, spring, lake, stream and bore water (all ground waters). A UV lamp dosage intensity of 30mJ/cm or greater eliminates most water born bacteria. For example, Anthrax spores and Aspergillus Glaucus requires a dosage of about 46mJ/cm, E.coli requires a dosage of 10mj/cm.

When UV is used for treating mains or city water sources a UV dosage of 16mJ/cm is acceptable. For mains water the UV is used as a backup in case the water supply authority get their water dose wrong as in the Hawkes Bay situation. Generally UV filtration is not considered necessary to use in water treated with chlorine. However it should also be noted that chlorinating the water supply does not eliminate all bacteria. For example It does not eliminate Cryptosporidium that causes diarrhoea.

Ultraviolet can also be used for the treatment of swimming pool water. UV will eliminate the need to use chlorine or chemicals in the pool water. Also when used for hot water return systems Ultraviolet controls Legionella with a dose of 12mJ/cm.

Why UV treatment?

Ultraviolet (UV) light in water treatment is a highly effective and proven water disinfection method. It offers many advantages over other disinfection methods like chlorination and ozonation. For example UV does not add anything to the water, it does not generate waste by products that may be dangerous. UV uses radiated energy to disinfect the water supply. It is environmentally friendly, effective, efficient, economical and very fast.

The Ultraviolet process utilises a formula based on waterflow, turbidity, chamber width, chamber length and lamp wattage. Water UV sterilisation systems are manufactured carefully to provide just the correct germicidal UV dosage in the disinfection chamber. This dosage works by a function of time and light intensity. So higher flow rates will result in lower exposure durations and lower flow rate will result in higher exposure times. The longer the exposure the better. These faster flows require higher powered UV lamps.

The UV Process:

      • Water is connected to the filter inlet. It flows through the filter housings and is filtered by the internal media. The filter media is customised to address any water issues. So very dirty water may require different or more filters to say that of cleaner water. Having been through the filter process all the floating contaminant matter is removed. It then flows into the stainless steel UV chamber.


      • Any bacteria that is present in the water is exposed to these intense Ultraviolet rays whilst flowing through the UV chamber.


      • The water that flows out the UV Chamber is sterile, safe, clear and clean ready for drinking.


Ultraviolet disinfection and filtration systems only work efficiently with clear water which is why pre filtration is used. Ultraviolet light rays will not penetrate dirty, cloudy water. The floating particles in the water shield the bacteria from Ultraviolet exposure. Water clarity is required and is achieved by using filter cartridges of 5 micron or less.