Quick Answer
UV purifiers are relatively effective against many waterborne pathogens, but their efficacy can be reduced by factors such as UV dose, pathogen type, and water quality. They can inactivate 99.9% of Giardia and Cryptosporidium with a 2-mJ/cm^2 dose, but may not eliminate all viruses and bacteria.
Common Pathogens and UV Inactivation
UV purifiers are commonly used to inactivate Giardia and Cryptosporidium, two protozoa that can cause waterborne illness. These pathogens can be inactivated with a UV dose of 2-mJ/cm^2, which is a relatively low dose. However, some bacteria such as Clostridium perfringens can be more resistant to UV and may require a higher dose to achieve inactivation.
UV Dose and Water Quality
The effectiveness of UV purifiers can be affected by water quality, including turbidity and organic matter. High levels of turbidity or organic matter can reduce the UV dose that reaches the pathogens, making it less effective. In such cases, pre-treatment of the water, such as sedimentation and filtration, may be necessary to improve UV efficacy.
Viruses and Bacterial Inactivation
While UV purifiers can effectively inactivate many bacteria, some viruses such as norovirus and rotavirus can be more resistant to UV inactivation. Bacteria such as E. coli can be inactivated with a UV dose of 1-mJ/cm^2, but may require a higher dose to eliminate all bacteria.
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