What’s a UV Water Purifier? How Does a UV Water Purifier Work?

Author: Rory Mullan - Published: 2022/05/25 - Updated: 2022/12/22

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UV water purifiers are a popular choice for water disinfection in many households. This is especially true in places where there’s a high level of biological contamination. They are used because they are effective and don’t require much maintenance.

But do you know how they work? What makes them so effective? Knowing how a water purifier system works can help you determine whether it’ll be good for you or not.

That’s why in this article, we’ll tell you everything you need to know about UV water purifiers, including how they work and how to maintain one.

So, here is our guide answering the questions, what is a UV water purifier and how does it work?


  • A UV water purifier is a tube-shaped appliance used for disinfecting water. It uses UV light to cleanse any water that goes through it.
  • UV water disinfection works because a brief exposure to the proper wavelength of ultraviolet light (254 nm) scrambles a microorganism’s DNA and destroys it.
  • Up to 99.9999% of microorganisms in a water supply can be neutralized by a UV purification system under optimal circumstances.

What Are UV Water Purifiers and How Do They Work?

How Does a UV Water Purifier Work thumbnail

A UV water purifier uses a UV lamp inside a tube-shaped device that’s normally attached to the plumbing of the house. The water passes through the chamber where it is exposed to UV light. The UV lamp is encased in a quartz glass sleeve that protects it from the water while still allowing the light to pass through.

Quartz is used for the sleeve due to its higher purity, as the impurities in normal glass wouldn’t allow the same amount of UV light to pass through.

Types of UV Purifier Systems

There are different types of UV systems based on their strength and the flow rate that they have to handle. For most regular households, a standard UV lamp is used. These are enough to handle low to medium flow rates, which is what you usually see in most homes.

A high-output UV lamp is used in commercial settings where a higher flow rate is found. These can handle the increased flow without compromising their effectiveness. However, they use more power and are more expensive.

In some cases, special UV lamps with vaporized mercury are used. These are significantly more powerful and are used in environments with very high flow rates for water.

UV purifier systems are also categorized as whole house or point of use systems.

How Does UV Water Purification Work?

UV water purification systems use ultraviolet light to kill microorganisms. UV light is deadly to them, with short exposure scrambling their DNA[1] which neutralizes them, prevents them from reproducing, and is extremely effective at killing them.

With optimal conditions, a UV purification system will neutralize at least 99.99% of all microorganisms in your water supply. These optimal conditions include water that isn’t too mineral heavy, and the absence of suspended particles. This is because both of those elements can affect the effectiveness of UV systems.

You can reduce their impact through the use of pre-filtration systems.

Does Ultraviolet Light Water Disinfection Remove Contaminants from Water?

It’s important to note that UV water purifiers don’t actually remove contaminants from your water. They only target microorganisms and sterilize your water supply by killing or neutralizing them. However, they don’t remove them.

Furthermore, they can’t filter out chemicals, heavy metals, salts, or other particles either.

In fact, the presence of these contaminants in the water can be detrimental to the performance of a UV purifier. For one, they create blind spots where the UV light can’t reach the microorganisms, and they can cause a buildup of grime on the surface of the glass sleeve, which affects the ability of light to pass through it.

bacteria under microscope

Lastly, a UV purification system doesn’t affect the taste or smell of water. This is excellent if your water is already clear of any bad smells and has good taste but won’t help you if it’s the other way around.

What Components Does a UV Water Treatment System Have?

A UV water purifier system is typically composed of 4 components. These are:

UV Light Bulb

The UV lamp is the main component of the purifier system. This is a long bulb that emits light in all directions and sits inside the main chamber.

Quartz Sleeve

The UV bulb is encased inside a quartz glass sleeve. This sleeve separates the bulb from the water while still allowing the light to go through. Quartz glass is preferred to regular glass as it has a higher purity which allows more light to pass through. Ordinary glass absorbs more UV light, and suffers from a solarization effect, where the glass becomes foggy when exposed to UV light for long periods of time.

Reactor Chamber

The quartz sleeve and UV lamp go inside a large encasing chamber, also known as the reactor chamber. The water flows inside the chamber where it’s exposed to the UV light, and then out of it to the rest of the household.

Controller Unit

In a lot of cases, the UV purifier will also have a control unit to manage the operation of the UV light. It could be a simple on and off switch, or a more complex system. The latter of these can have light level sensors for the UV light to let you know when its potency is diminished, or a light bulb change timer. Both of these are for maintenance purposes. They can also have an alarm to let you know if the power goes off in the unit.

How Effective Are UV Purifiers? Are They Safe?

When installed properly, and supported by additional pre-filtration systems, UV purifiers are one of the safest and most effective methods to disinfect your home’s water supply.

As mentioned before, they can reach 99.99% of effectiveness when killing or neutralizing microorganisms in your water supply, under the right conditions. Plus, they are perfectly safe, as they don’t affect the composition of your water at all.

These conditions include pre-filtering to reduce the number of solids in the water, and proper maintenance. You need to remove these solids as they can affect the performance of the UV system.

If your area has a high level of minerals in the water, also known as water hardness, you’ll want to soften it before it reaches the filter. Hard water fogs up the quartz sleeve faster, which would mean more maintenance.

Your sleeve will have to be cleaned and eventually replaced, and the frequency of that will depend on how hard your water is. A UV water purifier needs a clean sleeve to work at top efficiency.

Maintaining Your UV Purifier

As we mentioned before, you need to properly maintain your UV purifier for it to remain effective. While they require little maintenance when compared to other systems, you still need to keep an eye on them.

There are two items for you to work on when talking about maintenance: the UV light bulb and the quartz glass sleeve.

For the UV bulb, you should change it at least once a year. The reason for this is that UV bulbs lose about 40% of their potency and effectiveness within 9,000 hours of operation.

As for the quartz glass sleeve, you’ll need to clean it and eventually replace it. Typically cleaning the sleeve at least once a year should be fine, but you might need to clean it more often if your water has a high hardness level. Eventually, you’ll have to replace the sleeve as it fogs up over time, which can’t be fixed. Sleeve replacements should happen about once every two years, but they could be increased in frequency for the same reasons we mentioned before.

Another thing you’ll want to check is the sealing rings at the end of the purification unit. They tend to last very long, but you still want to keep an eye out for leaks and address those immediately.

uv light bulb

Why Should You Use a UV Water Purifier?

If you live somewhere where contamination of the water supply by biological elements is a concern, then a UV water purifier is an excellent choice. This is especially true for households that use a well for water.

However, we should note that a UV purifier works best when used in conjunction with additional filtration systems. You should have a filter that can remove suspended particles in the water to achieve the maximum level of purification possible.

If you are not sure whether you need a UV purifier for your household, you could have your water supply tested for contaminants. That way you can know if your water is contaminated by bacteria or other potentially harmful microorganisms.

Even if the test results are great, you should still consider a UV purifier system. That way you would be protected in the long term and prepared for any eventuality.

What Are the Pros and Cons of UV Water Purification Systems?

No water purification system is perfect. UV purifiers have their own advantages and disadvantages, and it’s important to know them before settling for one.


Among the many perks of using a UV purifier we can mention:

Highly Effective and Energy Efficient

UV water purification systems have an effectiveness rate of 99.99-99.999% when it comes to killing microorganisms, at least under optimal conditions. They are approved by the FDA and are generally considered one of the best methods out there for water purification.

Furthermore, UV systems don’t use any pumps, fans or components that draw power other than their lamp. And even their lamps use about as much energy as a house lamp.

No Chemicals Needed

UV filtration systems only need UV light to work, so you don’t have to add any chemicals to your water. This has the added benefit of protecting your pipes from damage.

Simple Design

A UV system doesn’t have any complex components, moving parts or electronics (other than the controller). You don’t have to do much beyond cleaning and replacing the glass sleeve and the UV light bulb about once a year.


As far as downsides go, UV purifiers have the following:

They Neutralize Contaminants in Water, But Don’t Remove Them

UV purifiers have one job: kill microorganisms. In that area, they are excellent. What they don’t do is remove their dead bodies from the water, or any other water contaminants for that matter. That’s why it’s better to complement them with other treatment systems.

Need Supportive Filtration Systems to Deal with Suspended Particles

This point builds up on the last one. Since UV filtration systems don’t remove particles from water, they can build and cause issues with their ability to perform. Particles in the water can block the ability of the UV light to kill all organisms[2], not to mention they can build on grime on the quartz sleeve.

Doesn’t Work without Power

UV water purifiers work through a lamp, which needs energy. If the power goes out, so does the system. Water will continue to flow without issue, but it won’t be disinfected. This can be especially problematic if, for whatever reason, only the area where the filter is plugged loses power. You could go on using non-disinfected water without knowing it unless you knew the unit is powered down.


UV water purifiers are excellent water purification methods that need very little maintenance.

They are safe to use, and don’t require a lot of space in your home.

Their advantages more than make up for the few shortcomings they have.

Now that you know what they are and how they work, you can decide if they are what you need for your household.

Every home is different, but it can’t be denied that UV water purifiers are excellent in most cases.

Further Reading


Meet Rory Mullan

Rory Mullan Rory has joined the Water Masterz team as a contributing writer. He has covered all sorts of topics in the last several years.

Outside of his writing work, Rory enjoys photographing the Irish landscape and making music!

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