In some regions, it may be required to implement a multi-barrier strategy (New York City’s Drinking Water for example) at the water treatment plant to protect the water supply from a wide variety of pathogens. UV is able to inactivate chlorine-resistant microorganisms like Cryptosporidium and Giardia, along with other waterborne pathogens that traditional disinfection methods would inactivate. Various plants have used a combination of ozone or chlorine in conjunction with UV in order to eliminate the risk of pathogens that are resistant to chemical forms of disinfection (e.g. the Metro Vancouver Coquitlam Plant in Canada uses ozone, chlorine and UV).

UV disinfection does not form disinfection byproducts nor impact the taste or odor of the water. It is also easily integrated into existing treatment processes because it does not alter nor is it affected by water chemistry (i.e. pH). UV systems are extremely compact due to the short retention time for UV (in most cases within a second). This allows an existing plant to easily retrofit their process to incorporate UV disinfection.