UV Bulb Replacement – How to Change a UV Light Water Filter

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One of the most attractive features of UV water filters is that they require relatively little maintenance. Only two parts need regular replacement – the UV light bulb and the quartz glass sleeve. The bulb should be replaced every year, while the quartz glass sleeve can usually last for two years.


How to Replace a UV Light Bulb?

1. Shut Off the Water Supply

Start by shutting off the water supply. If you have a bypass valve, open it, and close the valves at the input/output of your UV water filter. Close the input valve first, wait a few seconds, then close the output valve.

2. Remove the Protective Cap

Next, you need to remove the protective cap at the top of your UV water purifier. In many models, it’s enough to pull on it with some force. Some designs might require you to unscrew the cover first.

3. Unplug the UV Water Filter from the Power Supply

Disconnect the ground wire (in case there is one) by unscrewing the bolt which keeps it in place. After that, unplug the power cable from the UV filter. You may hear an alarm – this is normal. The device is alerting you that its power supply has been cut off. The alarm sound should subside after some time.

4. Remove the Old Bulb

burned out UV light bulb

You’re now ready to remove the old UV light bulb. Before proceeding, put on a pair of rubber or latex gloves. You should never touch the surface of a UV light bulb with your bare hands. Any skin oil residue can cause permanent damage to the bulb due to the heat it produces. This also applies to your old bulb, as it will probably be very warm when you pull it out of the purifier.

Touch the main chamber to verify that it’s cool enough to handle. If it’s still hot, wait a few minutes before proceeding.

To remove the UV bulb, simply unscrew it until it’s free. Pull it out of the reactor carefully. The bulb is quite long, and you should keep it straight until it’s fully out of the purifier to avoid breaking it. Handle it with caution – it contains mercury, so dispose of it carefully and avoid breaking it at all costs.

5. Insert New Bulb and Secure It in Place

Take your new UV bulb – again, only touching it with gloves on – and carefully insert it into the slot. Keep your hands as steady as possible. Even a tiny scratch can affect the performance of a UV light bulb, preventing some of the light from leaving the bulb. Even worse, a scratch could eventually turn into a crack and cause your bulb to explode.

6. Check for Leaks

Before plugging the filter back in and closing the cap, you should check for leaks. Turn the water supply back on, turn on a faucet and wait for a couple of minutes. Once water starts coming out of the faucet, go to the UV purifier and see if there are any signs of leakage around the seals.

7. Reconnect Your UV Water Filter

Once you’re sure that the new lamp is properly installed, it’s safe to reconnect the UV purifier’s power supply and close the cap. Don’t forget to connect the grounding wire!

How Often Do You Need to Change Lamps?

Standard UV light bulbs are rated for 9,000 hours of continuous use. With 8,760 hours in a year, this means that lamps should be replaced annually. Under some circumstances, you might have to replace it more frequently. For example, if you often switch your UV purifier on and off, its UV bulb might wear out faster.

Signs to Know When to Replace

Some UV water purifiers have a built-in UV monitoring system that continuously evaluates the current performance of the lamp and alerts you if it needs replacement.

In other devices, their system doesn’t actually measure the UV output of the lamp, but simply counts down over a period of one year.

If you don’t have any integrated monitoring, you will have to manually keep track of how long the lamp has been in use. UV light is invisible to the naked eye, so it’s not possible to examine the current state of the purifier visually.

Cracks in the bulb’s glass are the only visible hint that a replacement is necessary. However, you should avoid taking out your UV light bulb for random visual inspections too often, as you risk scratching or cracking the glass in the process.

Why Are UV Bulb Replacements Required in the First Place?

Unlike regular light bulbs, UV bulbs don’t burn out with prolonged use. Instead, they gradually lose their intensity. Standard UV bulbs used in water purification systems lose about 40% of their intensity within 9,000 hours of continuous use. This means that your purifier will be operating at nearly half of its original efficiency after one year.

Is It a Good Idea to Turn My UV System Off When Not in Use?

You might be tempted to turn off your UV water purifier when you’re not using it to conserve the life of its light bulb. In reality, this can shorten the bulb’s lifespan. Each power cycle causes additional wear on the bulb. In some models, the lamp’s controller might also be affected negatively if you turn it off and on too frequently.

If you’re going away for longer – like going on vacation for a couple of weeks – then it’s probably okay to turn off your UV purifier. Make sure to close its input and output valves to prevent any water from making its way inside the chamber. Still water, especially when left unattended for a longer period, can be an attractive breeding ground for microorganisms.

Are UV Water Purifiers Safe?

UV water purification is one of the most effective and safest water disinfection methods on the market today. Ordinary household purifiers can kill off 99.99% of microorganisms in the water supply. They do this without the use of any chemicals.

In fact, nothing is mixed into the water at all. Water never even comes in contact with anything other than the internal piping of the purification unit. Exposing it to UV light is enough to kill most of the microorganisms it contains.

As long as a UV water purifier is maintained properly and bulb/quartz sleeve replacements are carried out regularly, it’s a safe way to treat water.

bacteria in water

Soft vs Hard Glass UV Lamps

Hard glass is commonly used for the casing of UV light bulbs and the quartz sleeve found inside a UV water purifier. Its chemical composition makes it more suitable for this application, as it allows UV light to pass through more easily.

Soft glass is closer to regular glass used for windows. Its impurities reduce its ability to transmit UV light. In addition, soft glass suffers from solarization when exposed to UV rays over time. This further reduces its light transmittance. The sleeve encasing the UV light bulb is made of quartz for this reason.

It’s always advised to use hard glass UV lamps in a water purifier. Soft glass lamps can also work, but they require much more frequent replacement. Typically, a soft glass UV light bulb will need to be replaced every three months when used continuously.

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If you have any questions about how to change a UV light water filter please don’t hesitate to leave a comment below!

About the Author Gene Fitzgerald

Gene Fitzgerald has been with BOS since the very beginning. She is head of content creation and has fully immersed herself into the home water treatment industry only to become an expert herself. Outside of BOS, Gene loves reading books on philosophy & social issues, making music, and hiking.
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