Ultraviolet (UV) water purification systems work by using UV-C or “germicidal UV” radiation, which is much more intense than regular sunlight. These systems concentrate almost all of their UV output at a wavelength of 254 nanometers (nm), which is particularly effective at killing harmful microorganisms like viruses, bacteria, molds, algae, yeast, and oocysts such as Giardia and Cryptosporidium.
Most UV water purification units are paired with other filtration methods because UV light is great at eliminating biological pollutants but doesn’t affect chlorine, volatile organic compounds (VOCs), heavy metals, or other chemical impurities. That said, UV purification is one of the most affordable and effective technologies for getting rid of biological contaminants in drinking water. Recent studies suggest UV light can also diminish some VOCs, but it’s not recommended as a sole method for this purpose.
One of the biggest advantages of UV water purification is that it doesn’t add any chemicals to your water. This means no by-products are produced, and the pH, taste, and other properties of the water remain unchanged. On top of that, it’s safe for your plumbing and septic systems and is easy and cost-effective to install and maintain without needing special training.
How does it work? UV purification uses a UV light bulb enclosed in a transparent sleeve, usually made of quartz-crystal. The bulb is positioned so that water passing through a chamber is exposed to UV-C rays. When microbes in the water come into contact with these rays, their nucleic acid absorbs the UV radiation, which destroys their DNA structure. This renders the microbes unable to reproduce, making them dead and harmless.
UV treatment is an excellent choice for eliminating biological contaminants in drinking water, whether from a municipal supply or a private source like a well, lake, or spring. However, it’s essential to pair it with other filtration methods, such as reverse osmosis or carbon block filters, to handle chemical impurities like VOCs, chlorine, and heavy metals.
UV treatment is incredibly effective against all known microbes, unlike chlorine, to which some microorganisms can become resistant. UV radiation is especially good at killing viruses, bacteria, molds, algae, and disease-causing oocysts. It can eliminate over 99.99% of pathogens, including E. coli, Typhoid fever, Gastroenteritis, Cholera, Tuberculosis, Legionnaires’ disease, Polio, and Influenza viruses.
While countertop UV purifiers are not usually recommended for removing oocysts without a 0.5-micron carbon block pre-filter, whole-house UV systems can handle these complex microbes if you choose the right model for your needs.