Ultraviolet Disinfection

What is Ultraviolet Disinfection? 

  • Method of disinfection using short-wave ultraviolet light to kill or deactivate microorganisms that could be present in the water. 
  • Uses light at wavelengths of  260-270 nano metres known as UV- C to break the molecular bonds in the DNA of microorganisms. 
  • This will kill or deactivate the bacteria and prevent it from reproducing.
  • Widely accepted as a primary method of disinfection for potable drinking water offering a 3 log (99.9%) reduction in targeted organisms. 

Why is UV Disinfection useful? 

As an alternative or supplement to traditional chemical disinfectants, an ultraviolet disinfection system offers several operating advantages. UV disinfection systems are safe and easy to operate. In addition, the use of UV does not inject any taste or odour into the processed water, nor does it produce any undesirable by-products. 

There are no micro-organisms known to be resistant to UV light. UV is known to be highly effective against bacteria against bacteria, viruses, algae, moulds, and yeasts. In practice, bacteria and viruses are the causes of most waterborne pathogenic diseases. Of these enteric viruses, hepatitis virus and Legionella pneumophila are readily eliminated by UV treatment. For most microorganisms, the removal efficiency of UV for microbiological contaminants such as bacteria and virus generally exceeds 99.99. 

It is recommended that UV systems should be installed with pre-filtration to maintain effectiveness as sediment and other contaminants in the water can create a “shadow” which prevents the UV rays from reaching and disinfecting the harmful microorganisms. 


Once installed units must be regularly serviced and the lamps and quartz sleeve replaced periodically. Typically, a life expectancy of a lamp is usually 8000 operating hours. After that period, the ability of the lamp to emit UV radiation will decrease significantly. 

Quartz sleeves, just like UV lamps, wear out over time. Quartz will lose its ability to transmit UV rays into the reactor chamber. To maximise the optimal performance of any UV unit, manufacturers recommend that the quartz sleeves be replaced with each lamp replacement.