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What Is a UV Water Purifier?

A UV water purifier is a device that uses ultraviolet (UV) light to render the bacteria, cysts, and other microorganisms in water harmless. Ultraviolet light is a form of radiation that can damage cells, and when it's used in the correct dose, it can prevent waterborne pathogens (like E. coli, Giardia lamblia, and Cryptosporidium) from reproducing. If dangerous microorganisms cannot reproduce, they cannot make you sick.

Understanding UV

Ultraviolet is a wavelength of light that cannot be seen by the human eye. It falls right under Violet in the "ROY G BIV" colors of the rainbow acronym that you may have learned in school. Most of us are probably familiar with the term "UV" because of its role in the development of skin cancer. The sun produces UV light, some of which penetrates the atmosphere and reaches the earth. Too much exposure to ultraviolet light can damage the DNA of your skin cells and promote the development of cancer.

There are actually three types of UV light: A, B, and C. The ones that we're warned about protecting ourselves against are UV-A and UV-B, since those are the wavelengths that penetrate the atmosphere and can cause skin damage. It's actually UV-C that's the most dangerous; it gets blocked by the upper atmosphere, so it usually doesn't really have an impact on our daily lives. UV-C can be used as an effective weapon against bacteria and other pathogens, however.

All types of UV light can damage cells, which is why we're advised to wear sunscreen to protect ourselves from the sun. UV-C is considered to be "germicidal" radiation, which means that it can inactivate germs. This form of radiation alters the DNA in the cells of the microorganisms, preventing them from reproducing correctly. UV light can be used not only to help disinfect water, it's also been used to clean the air, laboratory equipment, and fruit juices.

The Parts of a UV Water Purifier

To understand how a UV water purifier works, it helps to start with what the UV water purifier parts are. A basic UV system is made up of four main parts:

  1. The UV lamp
  2. A ballast or controller unit
  3. A quartz sleeve
  4. The reaction chamber

The water to be treated flows into the reaction chamber, where it is exposed to UV light. The UV lamp is enclosed inside the quartz sleeve, which protects it from direct exposure to the water (which could damage the electronics of the system). It's important that sleeve that protects the lamp be made of a special type of glass that does not block or disrupt the UV light. The ballast or controller unit provides power to the lamp and may also control the flow of the water through the system. Many UV water purifiers include a warning light to indicate when the lamp needs to be changed, but it should be replaced once a year.

Advantages and Disadvantages of UV Water Purification

While UV is a very effective way to kill pathogens in water, there are also a number of UV water purifier disadvantages.

UV Water Purifier Advantages

  • Systems are relatively inexpensive
  • Works quickly and with no moving parts
  • Electricity requirements are very low
  • Does not add harmful chemicals to the water
  • Easy to maintain and does not require constant monitoring
  • Does not create any potentially dangerous byproducts

UV Water Purification Disadvantages

  • Requires a source of electricity and stops working when the power goes out
  • Does not improve the taste or feel of water and does not remove any contaminants
  • UV lamp must be replaced yearly, and the bulb (which contains mercury) must be disposed of properly
  • The untreated water must be relatively clear, or the treatment cannot work as effectively
  • Offers no residual disinfection; once the water leaves the reaction chamber, it could be re-contaminated

If you have any questions about UV water purifiers or how to disinfect your drinking water, please call our Certified Water Specialists at 1-800-608-8792 and we'll be happy to help you determine which system is right for you.