What is UV Water Filtration?

Understanding How UV Water Filters Work

UV water disinfection is an effective way to make sure all the water coming into your home is microbiologically safe. Gain insights into how ultraviolet light effectively eliminates viruses and bacteria from your water.

In This Article
Bullet point
Bullet point
Bullet point
Bullet point
Bullet point

How Does a UV Water Purifier Work?

The UV water disinfection process utilizes special UV lamps or bulbs that emit UV light of a particular wavelength. These UV light waves have the ability, based on their length, to disrupt the DNA of microorganisms. These UV light waves are referred to as the Germicidal Spectrum or Frequency, the frequency used in killing micro-organisms is 254 nanometers (nm).

During the UV water disinfection process, as water passes through a UV water treatment system, living organisms in water are exposed to UV light which attacks the genetic code of the microorganism and rearranges the DNA /RNA, eliminating the microorganism's ability to function and reproduce.

If a microorganism can no longer reproduce, it cannot replicate, therefore it cannot infect other organisms with which it has contact. This process of exposing water to UV light is simple, effective, and destroys 99.99% of harmful microorganisms without adding any chemicals to water.

Check out our UV System Buyer's Guide or take our Interactive UV Filter Selection Quiz to help you choose the UV sterilizer that's the right fit for your home or commercial application.

Sold out
  • Compact, yet powerful design treats water with UV light, plus includes an
  • Integrated pre-filter that can remove sediment, dirt and rust for improved taste.
  • Includes a lamp replacement timer.
  • Proven UV system with premium-quality parts at a value price.
  • Treats up to 9 gpm, perfect for a home with 1-3 bathrooms.

What Type of UV Light is Used to Treat Bacteria in Water?

Ultraviolet or “UV” is a type of energy found in the electromagnetic spectrum, lying between x-rays and visible light. A UV light water sterilizer system utilizes ultraviolet light to combat waterborne pathogens, while adding nothing to the water. UV is a safe, economical way to protect your household from illness-causing viruses and bacteria in water.

UV type of energy found in the electromagnetic spectrum

How Is Ultraviolet (UV) Strength Measured?

The UV light, 254 nm, is measured in water treatment as Milli-joules per Centimeter square. The United States Department of Health has determined that an effective UV system should provide a minimum of 30,000 Milli-joules per Centimeter Square for drinking water applications.

Sold out
VIQUA IHS22-D4 UV Water Treatment System
  • The Viqua IHS22-D4 inclues two integrated prefilters to improve the taste and odor of your water.
  • LED Status system indicator.
  • All-in-one UV solution boasting added layers of water filtration and treatment.
  • Safeguards ALL the water coming into your home.

What are the Pros and Cons of UV Water Filtration?

Municipal water suppliers perform the necessary operations to meet water quality standards, but UV purification systems take water treatment to a higher level—providing a safe solution against chlorine-resistant microorganisms such as Giardia and Cryptosporidium which cause thousands of documented health cases each year.

Before purchasing a UV water disinfection system, it's important to examine UV water purifier pros and cons.

UV Water Treatment at a Glance

Check mark
Kills 99.99% harmful microbes
Check mark
Environmentally friendly
Check mark
Treats water 24/7
Check mark
Simple installation and maintenance
X mark
Only treats microbiological contaminants
X mark
Needs electrical power
X mark
Doesn't improve taste of water
X mark
May require prefiltration

UV Water Treatment at a Glance

Kills 99.99% harmful microbes
Environmentally friendly
Treats water 24/7
Simple installation and maintenance
Only treats microbiological contaminants
Needs electrical power
Doesn't improve taste of water
May require prefiltration
UV Water treatment has many pros

Advantages of UV Water Disinfection

Advantage 1

Go green! UV is an environmentally-friendly alternative to chlorine disinfection and has no disinfection byproducts.

Advantage 2

Ultraviolet works 24/7 to consistently keep your water safe from harmful microbes.

Advantage 3

Once installed, annual lamp replacement and sleeve cleaning is basically all that is needed to maintain a UV water disinfection system.

Advantage 4

A UV light water sterilizer works by damaging the DNA of microorganisms, including bacteria, viruses, and protozoa, thus rendering them unable to reproduce and causing them to die. UV destroys 99.99% of viruses and 99.9999% of bacteria in water, making it more effective than chlorine and chloramine for killing many harmful waterborne microbes.

Advantage 5

The UV process takes up very little space. No holding tank is needed and essentially no water pressure is lost.

Advantage 6

As water flows through the UV system, the water is instantly treated without the need for a holding tank or reaction time.

Advantage 7

The UV purification process does not waste any water and has very low electrical needs.

Advantage 8

UV sterilizers eliminate the need for handling chemicals and the disposal of dirty filter parts.

Disdvantages of UV Water Disinfection

While there are many advantages of UV water disinfection, it's important to understand the limitations of this treatment method before purchasing a UV water sterilizer system.

Disadvantage 1

UV technology destroys only waterborne microorganisms (viruses, bacteria, cysts, etc) and does not remove any other contaminants such as lead, pesticides, chlorine or man-made substances like petroleum products or pharmaceuticals. For this reason, integrated UV systems pre-assembled with sediment and carbon filters are popular.

Disadvantage 2

If water is murky or contains “floaties,” UV light cannot effectively reach microorganisms because the rays are blocked by these other particles. A prefilter may need to be installed in front of the UV sterilizer system. This is especially important with UV light for well water, when ultraviolet is the only source of water treatment and it's important to get best results from UV.

Disadvantage 3

While some treatment methods (such as point of use reverse osmosis filter systems) do not need electricity, a UV water sterilizer requires power. For this reason, UV treatment of water may not be suitable for all applications-- such as rural settings or emergency or survival needs when electricity may not be available.

Disadvantage 4

For some, this might be an advantage. But if you're looking to improve the taste and odor of your water, you'll want to install either a reverse osmosis drinking water system WITH your UV water sterilizer or purchase a combo system that preassembles a UV unit with sediment and carbon filtration (such as the Viqua UV Light VH200-F10 system).

Overall, UV treatment of water is an outstanding way to meet your water purification needs. UV has proven to be one of the most reliable, quick, and cost-effective methods for disinfecting water at both point-of-use (kitchen tap) and point-of-entry (whole-house) applications.

Top-Selling UV Water Sterilizer

Viqua D4 Premium UV Water Treatment System

The VIQUA D4 Premium features the compact footprint and advanced lamp/chamber technology of the D4 with an updated LCD controller powered by UV MAX Trojan. The new LCD controller simultaneously displays total UV lamp life remaining, support information, and lamp replacement reminders to help make sure your water is always safe. Capable of 100-240V, 50-60Hz. Learn more >

Sold out

Chlorine vs. UV Disinfection in Water Treatment

This short video explains how some waterborne microbes are chlorine resistant. UV water disinfection is the most effective method for destroying illness-causing microbes in water.

Video courtesy of Viqua

What Contaminants Can UV Light Remove from Water?

Biological Contaminants Destroyed by UV


E. coli


hepatitis A







typhoid Fever






Are UV Water Filters Safe?

Sometimes customers ask, "are UV water purifiers safe?"

UV disinfection has come a long way since it was first invented. And although UV is a new idea to some, ultraviolet technology has been used for decades by municipal water suppliers and commercial water bottling plants.

While most skin cancers are a result of exposure to UV rays in sunlight, the UV rays in water disinfection UV system do NOT cause cancer. The entire process of exposing water to UV light takes place in an enclosed chamber, posing no risk to family or pets.

UV disinfection is approved by the EPA (Environmental Protection Agency) and is an environmentally friendly disinfection method. The UV process is chemical-free and creates no byproducts. Because UV is simple, swift and safe, millions of homes and businesses now use ultraviolet technology to disinfect their water.

What are the Parts of a UV Water Disinfection System?

There are a variety of ultraviolet water purification system makes and models, but most of them have the same basic components. Below is a list of the nine most common components of a UV sterilizer.

Diagram of UV Water Purification System and Parts

1. Ballast or Controller

The UV system's ballast is the “brains” of the unit. Some systems have a very simple controller, and others have a more complicated system that includes alarms, lamp change timers, trouble indicator lights, and more. Although UV units vary in complexity and size, all controllers do basically the same thing of controlling the electrical output of the lamp and powers the UV-C light needed for water purification.

2. Water Inlet

The water inlet is simply where the piping connects to bring in untreated water.

3. UV Chamber

This part of the system houses the UV sleeve and lamp, and also controls the flow of water through the system.

4. Water Outlet

The treated water leaves the UV chamber from this part of the system.

5. UV Lamp

The lamp of a UV system (also called a UV bulb) produces UV-C, which is UV light considered to be germicidal. However, different lamps perform different functions, so the type of lamp used will be contingent on the application and disinfection requirements.

6. UV Quartz Sleeve

The quartz sleeve of a UV system is the long, cylinder-shaped tube. The tube is made of quartz glass and is there to protect the UV lamp which is powered by electricity from the flow of water. The UV lamp transmits light through the tube into the water. It is important to clean the sleeve (generally when the lamp is changed) as minerals and contaminants in the water can cloud the glass tube.

Options available when purchasing a UV system include:

  • UV Sensor - Available option on most UV systems, the UV sensor monitors and indicates the intensity of the UV light. If the intensity becomes too low, even though the UV bulb is on, an alarm is triggered.
  • Solenoid Valve - Available option on most UV systems, the solenoid valve automatically shuts the water off if the system is not functioning properly, preventing the possibility of contaminated water flowing through the system that is not treated properly.
  • Flow Meter - Standard on some UV systems, the flow meter calculates the actual real-time UV dose delivered for a particular flow rate, ensuring water is treated properly.

Ultraviolet Technical Tips

How to Change a UV Lamp

Instructions on how to replace a UV water sterilizer lamp yourself, including step-by-step instructions and video.
Read More>

How to Clean a UV Sleeve

Cleaning the UV sleeve in an ultraviolet water sterilizer system is crucial to maintain optimal performance. Learn how to properly clean a UV sleeve.
Read More>

How to Maintain a UV System

Tips for proper maintenance of a UV water disinfection system. Find solutions, UV system troubleshooting tips and more.
Read More>

Explore Other System Types