UV Treatment of Pool Water
The Role of UV Treatment in Pool Water Sanitation
Following is an extract from UV Treatment of Pool Water-Fact & Fiction by Graham Smith. (UV) radiation is being used increasingly to both destroy harmful combined chlorine (otherwise known as chloramines) and act as an additional disinfectant barrier to complement the role played by free chlorine in swimming pools.
Importantly, both UV and free chlorine have a role to play in the disinfection of pool water. While chlorine is very effective in destroying common water borne bacteria such as E. coli and various strains of faecal coliform, it is relatively ineffective against protozoan parasites such as Cryptosporidium and Giardia, which can readily contaminate a swimming pool via infected swimmers. These parasites are particularly pathogenic with those infected suffering symptoms including severe abdominal pain and diarrhea. In uncommon but extreme cases involving either the very young or very old, deaths have been reported from Cryptosporidiosis.
Having said this, UV should only ever be seen as a secondary pool water disinfectant, with chlorine used as the primary disinfectant. This is because chlorine has a very important property which UV lacks – the ability to provide a residual level of disinfectant in the pool water. This means, chlorine can remain in the pool water actively combating pathogens at the very moment they are introduced. UV on the other hand, can only disinfect the water as it passes through the UV chamber. Once the water has left the chamber, it is available to be re-infected by swimmers when the water returns to the pool. It is for this reason that most public and municipal swimming pools use UV systems more as a means to destroy harmful chloramines than as a disinfectant.
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