What is a key disadvantage of using an ultraviolet irradiator for disinfection in potable water systems?

Using an ultraviolet irradiator for disinfection in potable water systems has the key disadvantage of failing to provide a residual disinfectant. This means that while UV treatment can effectively inactivate pathogens present in the water at the time of treatment, it does not leave any chemical residual that continues to disinfect as water flows through the distribution system. As a result, once the water leaves the UV treatment area, there is no ongoing protection against potential recontamination or growth of microorganisms that could re-enter the water supply in the distribution system. This lack of residual disinfectant can pose a risk, particularly in systems where water is stored or transported over longer distances.

In contrast, many traditional disinfection methods like chlorination leave a chemical residual that continues to provide protection after treatment. Understanding the nature of residual disinfectants is crucial for ensuring the safety and quality of potable water.