What is a UV water purification system?

A UV water purifier disinfects biologically unsafe water (lake water, seawater, well water, etc.) without using any chemicals. A UV purifier is often used as pre-treatment and perfect for defense in natural disasters when the city water supply has been compromised. When a Boil Water Advisory (BWA) is issued, ultraviolet disinfection helps protect your water from bacteria and viruses that could make you sick. The UV light eliminates the need for chemical disinfectants, making ultraviolet water treatment an eco-friendly option.

We recommended a UV water purifier for:

• Well water
• Wastewater treatment
• Travel to remote areas

How does ultraviolet disinfection work?

A UV water purifier is made up of a chamber that encapsulates the quartz sleeve that protects the UV lamp. The UV lamp contains little beads of mercury that vaporize and fuel the lamp to emit UV radiation. One or two O-rings, held in place by the glad nut (or cap), hold the quartz sleeve to the chamber and keep water from leaking.

UV water purification does not remove contaminants from water. It deactivates 99.99% of microorganisms by altering their DNA so that they cannot reproduce and spread disease. Once the UV light attacks the bacteria, they’re no longer capable of infecting the water supply.

A UV water purifier deactivates:

• Cryptosporidium
• Giardia
• Dysentery bacilli
• Salmonella
• Mycobacterium tuberculosis
• Streptococcus
• E. coli
• Hepatitis B
• Cholera
• Algae
• Fungi
• Some viruses

Frequently asked questions: How do you install a UV water purifier? What are the loose beads in a UV lamp? Do I need UV disinfection for municipal water?

Visit our blog for the full list of FAQs about UV water purifiers and answers to these questions.

UV vs RO

Many people ask, “Which is better, RO or UV?” Reverse osmosis and UV disinfection have different jobs. An RO system uses a semipermeable membrane to filter microscopic dissolved particles, while a UV purifier deactivates bacteria and viruses with ultraviolet light rays. RO does not remove bacteria, and UV doesn’t reduce dissolved particles or sediment. So, one system is not better than the other. Before deciding on a water filtration system, conduct a water test. Knowing what’s wrong with your water will help you determine which system is best for you.

If you want to filter contaminants like chlorine, lead, dissolved solids, or volatile organic compounds (VOCs) and treat your water for bacteria and viruses, then you need a filtration system in conjunction with your UV system. To remove chlorine taste, find a system with carbon filtration. Find a system with sediment filtration to remove dirt and debris. If you need to reduce hardness minerals, then you need a water softener. A water softener protects the UV system by preventing calcium from scaling up the quartz sleeve.

Browse all water filtration systems.

Why you need a sediment prefilter with a UV system

Test your water before installing a UV disinfection system. Water flowing through a UV water purifier should be free of hardness, iron, turbidity, manganese, and tannins (color). The following water contaminant levels are recommended for UV systems:

• Hardness < 7 gpg (grains per gallon)
• Iron < 0.3 ppm (parts per million)
• Manganese < 0.05 ppm
• Turbidity < 1 NTU (nephelometric turbidity units)
• UVT < 75%
• Tannins < 0.1 ppm

If these levels are exceeded, scaling can decrease a UV system’s efficiency. Sediment could block the UV radiation and create shadowing in the UV chamber that allows organisms to pass through without being deactivated. Suspended solids, turbidity, color, or soluble organic matter can inhibit the ultraviolet dosage and reduce disinfection performance. Water turbidity makes it difficult for ultraviolet radiation to penetrate water.

A 5-micron sediment prefilter or prefilter kit will reduce dirt, sediment, bad odors, bad taste, and chlorine. We recommend that a water analysis is conducted prior to installation of a UV system if you are drawing from a lake or from some other "surface" water supply (lakes, rivers, well, etc.).

Why use a UV water purifier?

• Uses no toxic chemical byproducts
• Requires little contact time
• Produces high flow rates
• Adds no taste or odor to water
• Designed to run constantly
• Easy to maintain
• Wastes no water
• No holding tank needed

Is UV disinfection safe?

Treating water with UV radiation sounds dangerous, but it’s harmless. The UV bulb never contacts the water because it’s encased in a quartz sleeve. The quartz sleeve protects the water and the bulb from electricity.

How to Maintain a UV water purifier

A UV disinfection system is designed to run constantly and only needs to be shut off if it’s not going to be used for an extensive length of time. With proper maintenance, a UV purifier will last many years. Most systems have an indicator light to signal if it’s not running properly. Test your water periodically to guarantee that your UV system is effectively treating the water.

How often to replace the UV lamp: once a year (every 9,000 hours)

How often to replace the quartz sleeve: every two years to five years (or until the quartz sleeve can no longer be descaled)

Maintenance Tips

• Keep the chamber and quartz sleeve clean so particles don’t prevent the UV light from treating the water. Be sure to wear gloves when changing the bulb.
• Quartz sleeves are delicate, so it’s helpful to keep an extra quartz sleeve handy in case it breaks.
• Wait for the UV lamp to reheat and flush your plumbing before you turn on a UV system.

Residential vs Commercial UV Disinfection

UV water purifiers are point-of-entry (POE) systems installed at the main water line. A residential UV system is a reliable and cost-effective method of home drinking water treatment when used with a sediment filter. NSF class A systems are for use with water not treated at a plant (well water), and class B systems should be used with treated water. A commercial UV system are larger and usually have more lamps in the chamber than a residential system, which increases exposure to UV radiation and allows water to flow at a faster rate. A handheld UV purifier treats raw surface water during international travel and outdoor camping trips.

Where is commercial UV water purification used?

• Private wells
• Campgrounds
• Hotels
• Aquaculture
• Hospitals
• Cottages
• Restaurants
• Breweries
• Laboratories
• Marine vessels
• Pharmacies
• Dairy farms
• Water treatment plants

UV Water Purifier Reviews

Viqua S5Q-PA Silver Series System

Excellent product, easy installation

“I bought this for our main house after using an earlier version at our camp for 5 years, flawless operation, easy to change lamps.” -- Mark M.

Pura UVBB-3 UV System

We are very happy with this product.

“We use this to purify the water supply for our house in Guatemala and are very happy with it. We have found we experience less sicknesses after using this over bottled water and this is far more convenient.” -- Thomas T.

Sun-Pure UST-200 UV System

Off-Grid Perfection

“I have been using this filter off grid for 8 years and have replaced the low cost (30.00) lamp 5 times. We quit having the water tested 6 years ago, it was pointless, it's always perfect. Neither us or any guests have ever had an issue with waterborne bacteria.” --Donald J.

Browse residential UV water purifiers by brand: Viqua | Ultra Sun-Tech | Pura

Browse commercial UV water purifiers by brand: Viqua | Pura | Atlantic Ultraviolet Corporation | Polaris Scientific UV