Is UV Water Disinfection Right for You?
Ultraviolet (UV) light has been used for water disinfection since the early 20th century. Initially developed and utilized by public utilities and commercial facilities that needed to process water for beverage or food production, UV systems for home use have been gaining popularity since the 1990s.
To determine if this approach is right for your household, it’s important to understand how UV systems work, what they can and cannot do, and the advantages and disadvantages.
How UV Light Works
A form of electromagnetic radiation, UV light occurs between normal visible light and x-rays on the light spectrum. To disinfect water, a lamp capable of producing UV light at the right wave length (254 nm) is installed in a water chamber. As water passes into and through the chamber, it’s subjected to the UV rays for a prescribed length of time. The most effective UV lights are constructed of quartz glass which allows 95% of UV rays to pass through without disruption. Some units feature Teflon sleeves, but because the material absorbs up to 35% of the critical UV rays, they’re less effective.
What UV Light Does
Technically, UV light doesn’t kill bacteria or other microorganisms. Instead, the rays damage the organism’s DNA, which prevents it from multiplying in the water or in humans and animals. The process is described as microbial inactivation, and because they can’t replicate the organisms are rendered harmless.
The right dosages of UV light effectively neutralize 99.9% of bacteria including E. coli, parasites such as giardia and cryptosporidium, and viruses. Because viruses are more resistant to UV light, the dosage must be properly calibrated to effectively deactivate them.
What UV Light Doesn’t Do
While UV light is a very effective way to disinfect water, it doesn’t alter water quality in any other way. If you have issues with hard water, want to remove trace chemicals and contaminants, or reduce odors and particulates, you’ll need to invest in filtration and softening systems to accomplish those goals.
Advantages & Disadvantages
UV light effectively disinfects water without the need for chemicals such as chlorine, but it’s important to invest in a high quality system with a powerful UV lamp that emits rays at the optimum wave length. The system also needs to be designed and calibrated to kill viruses, which typically involves extending the disinfection time to increase UV exposure.
Basic water quality has a direct effect on UV disinfection. If your water is high in minerals, total dissolved solids (TDS) or suspended solids, for example, you’ll need to have pre- filtration and/or softening systems installed to reduce them, because they block UV light penetration and prevent microorganisms from receiving the full dosage required to inactive them.