How to Change a UV Lamp in a Water Filter? – Replacement Guide

Author: Rory Mullan - Published: 2022/05/25 - Updated: 2023/01/05

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When properly maintained, a UV water filter will keep you and your family safe from viruses, bacteria and other harmful waterborne pathogens. And maintaining a UV purifier is as simple as replacing the UV light bulb every year, and the glass sleeve every two years.

Trying to do this on your own might seem like a lot at first, but it’s actually really simple.

In this article, we’ll take you through the steps needed to replace your UV Bulb, as well as answer some common questions about UV water purifiers.

So, here is our guide on how to change a UV light water filter!


This is how you replace a UV light bulb:

  1. Turn off the water.
  2. By turning on downstream faucets, you can drain as much water as possible from the water line.
  3. Remove the UV system’s protective cap.
  4. Disconnect the UV water filter from the electrical outlet.
  5. Together with the quartz sleeve, remove the UV light bulb. Remember:  Wear gloves. A UV light bulb’s surface should never be touched with bare hands.
  6. Reinstall after replacing the bulb and putting it in the quartz sleeve.
  7. Restart the water supply and look for any leaks.
  8. Connect the UV water purifier to an electrical outlet.

UV Bulb Replacement – Step by Step Guide

how to change a UV light water filter thumbnail

Before we dive into the explanation, we’d like to preface it by stating that these are general guidelines. It’s always best to refer to the owner’s manual of your UV model for specifics, as there are many different systems out there.

With that out of the way, these are the general steps to follow:

1. Close the Water Supply Valve

The first thing you’ll have to do is shut off the water supply. If you have a bypass valve, you’ll have to open it and close the valves at the input/output of your UV water filter.

First, close the input valve and wait a few seconds for the water flow to die out before closing the output valve.

2. Take Off the Protective Cap

After the valve has been shut off, you’ll need to remove the protective cap at the top of your UV water purifier. Check the lid for screws if your model is screwed down, otherwise pulling on it with a bit of force should do the trick

3. Disconnect the UV System from the Power Plug

Once the cap is off, you’ll want to disconnect the UV system from the power supply. Check to see if there is a ground wire and unscrew it. If there isn’t one, then just unplug the power cable.

If you hear an alarm, don’t worry. That’s just the system letting you know that the power has been cut off. It should stop after a bit.

4. Carefully Remove the Used UV Bulb

With the valve shut off, and the power disconnected, it’s time to remove the UV bulb. First, give the old bulb a couple of minutes to cool down.

Before you go in, you should put on some rubber or latex gloves for protection. The reason for this is that oil from your skin can damage UV bulbs when they heat up.

Now, touch the glass sleeve to see if it has cooled down enough. If it hasn’t, give it a few more minutes.

If it has, simply unscrew the UV bulb slowly and carefully until it’s free. Then, pull it out carefully to avoid breaking it. Once it’s out, dispose of it with equal care. The bulb contains mercury, so you don’t want it to break at any point.

5. Carefully Install the New UV Bulb

With your gloves on, get your new bulb and carefully place it inside the reactor. You want to take your time as any scratches could lead to performance issues, or, even worse, cracks. A crack could eventually cause your bulb to explode.

6. Examine the Filter for Leaks

Now that your bulb is screwed on, you should check for leaks before turning everything back on. Simply turn the water supply on again, turn on a faucet, and check to see if any water leaks out of the purifier’s seals.

7. Plug the UV System Back On

With the lamp secured, and assuming there are no signs of leakage, all that’s left is to reconnect the power supply, including the grounding wire if there is one, and close the cap.

And you are done.

How to Know When Your UV Light Lamp Needs to Be Changed

There aren’t a lot of ways to tell when you need to replace a UV lamp, other than keeping track of how long it’s been in use. For one, UV light is invisible to the naked eye[1], so you won’t be able to tell if the intensity is diminishing. However, a telltale sign that your bulb needs replacing is if there are cracks in the glass. But even these are tricky as you shouldn’t be randomly taking out your lamp to inspect, as you could risk breaking it.

Luckily for you, a lot of UV purifier models come with built-in monitoring systems. Some of them check the performance of the lamp and let you know when the intensity is reduced below a certain threshold, and it needs replacing. Other systems simply count down from the moment the lamp is installed over a period of one year.

If your UV purifier doesn’t have any built-in monitoring, make a note of the moment you started using the lamp, and check the integrity of the glass every few months.

insides of a UV water purifier

Why Use Hard Glass UV Lamps Instead of a Soft Glass Ones

In general, you’ll be better off using a hard glass UV lamp rather than a soft one. The reason for this is that hard glass lamps have a chemical composition that allows UV light to pass more easily. Furthermore, they last much longer.

Soft glass used for UV lamps is more like that used in windows, which has more impurities. This makes it harder for these types of lamps to transmit UV light. On top of that, they suffer from solarization when exposed to UV rays for extended periods of time. This darkens the glass and reduces the amount of light it transmits even further. This makes it so soft glass bulbs need to be replaced more often. They tend to have a lifespan of 2,000 hours, or about three months.

Frequently Asked Questions About UV Water Purifiers

Why Do I Need to Replace the Lamp in My UV System?

That’s because UV light bulbs lose their intensity with continued use. They might not burn out, as normal light bulbs do, but they won’t be as effective. In general, a standard UV bulb will have lost about 40% of its intensity by the 9,000-hour mark. Not to mention, the excess energy used by an older lamp could end up causing issues for your system.

How Frequently Should I Change the UV Lamp?

We recommend replacing your lamp at least once a year. In general, UV light bulbs are rated for 9,000 hours of continuous use, which is a little over a year of life under normal circumstances. However, if your UV purifier is switched on and off frequently, the bulb will wear out more quickly.

If you make a habit of replacing it annually, you should be fine.

Should I Turn Off My UV System When It’s Not in Use?

Turning off your UV system for short periods of time can actually be counterproductive. The reason for this is that it ends up shortening the lifespan of the UV bulb. Each time you switch it on, it wears out the intensity of the UV bulb. In some cases, it can even end up damaging the lamp’s controller. So, if you are trying to make the system last longer, you should avoid turning it off and on frequently.

However, if you are taking a trip or otherwise going to be out of the house for a while, it’s fine to turn off your system. Just make sure to close off the input and output valves as well to keep any water out of the chamber, as water left there for long periods of time could lead to bacteria infestation.

Am I Safe Using a UV Water Purifier?

Absolutely. UV water purification is considered one of the safest and most effective disinfection methods available to households. It can kill off 99.99% of microorganisms that could breed in water, and all without the use of chemicals or any other product.

If your system is properly maintained, including replacing the sleeves and bulbs when needed, your water will be perfectly safe to drink.


UV Water purifiers are an excellent and perfectly safe way to ensure the water in your home is safe for you and your family.

With proper maintenance, a UV system will last you for a long time.

Replace your UV bulbs at least once a year following the steps we’ve covered, and you won’t have much to worry about.

Just keep an eye out for any signs that they need to be replaced sooner, such as cracks in the glass.

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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