Why do I need to replace my UV bulb?

Why it is important to replace your UV bulb regularly?

Our UV units all have replaceable UV bulbs, these bulbs deliver the UV light within the unit directly to where the water passes and need to be replaced regularly as they eventually wear out and become less effective.

It is important to replace the bulb so that you avoid a build of bacteria within the UV unit and end up consuming unsafe water.

Replacing your UV bulb should be part of the regular maintenance of your UV system, whether installed within a commercial or domestic property. Ideally, your UV bulb should be replaced every year* or after 9,000 hours* of use (whichever is soonest)*.

What happens if I don’t replace my bulb?

UV bulbs are not like traditional light bulbs that you replace when they are blown (no longer working), UV light can still be emitted from the bulb after a year* or 9,000 hours* of use. However, the level of UV light won’t be the same as a new blub and will be less likely to kill the bacteria in your water to make it safe to drink, cook with, or bath in.

The UV unit will eventually suffer from a build-up inside of bacteria, effectively water will pass through a glass tube and out the other end carrying the bacteria with it. You may as well not have a UV unit and have a direct feed from your water supply, the bacteria will no longer be killed and will stay present in the water that you are consuming or bathing in.

Consuming untreated, unsafe water can cause many health issues for your customers or family, as the bacteria that is still present in the water will be ingested causing adverse effects.

You have installed a UV unit within your household or business to clean the water that is entering your premises, to kill off the bacteria, and like with any piece of machinery it needs to be maintained to keep it working.

Should I replace my bulb even if it is still working after 12 months*?


The germicidal properties of UV bulbs are fuelled by mercury. Each UV bulb or lamp contains beads of mercury that create electrical arcs that disinfect the water that passes through the UV unit.

When heat is applied to the lamp the mercury emits UV-C light which has a wavelength that is capable of neutralising bacteria.

Once the 12 months* or the 9,000 hours* have passed, the effectiveness of the mercury has been exhausted and will no longer disable microorganisms within the water.

Therefore, we advise all our customers to change their UV blub every year (12 months) or after 9,000 hours of use.

How do I know when to change my UV bulb?

As a UV Water Filter customer, you will be able to check via your account accessed through our website as to when you bought your last bulb or complete unit.

Check the date and see how long ago that was, if it was over 12 months* then order a replacement and follow our helpful video to show you how to replace the blub.

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How to change a UV bulb or lamp

We can also send you a timely reminder to reorder a blub before the 12 months is due, if you are happy to receive emails from us. Make sure that you check the box within your account permissions for us to contact you.

If you want to check how many hours your UV lamp (or blub) has been running then you can check this via the ACL controller (the digital interface).

Atlas UV ACL controller
This is an ACL control unit of an Atlas UV unit

Any questions or concerns about your UV blub and how to replace it please do not hesitate to contact us and one of our service team will be able to help you.

*Please note: some amalgam/commercial lamps are rated at 18,000 hours

UV Water Filter

If you are looking into purchasing a UV unit to disinfection your water supply, then have a look at our wide range of products for domestic dwellings or commercial properties, we offer complete packages or individual units along with a comprehensive range of replacement bulbs for a variety of brands.

If you have any queries about installing an eco-friendly, low-energy, cost-effective water treatment unit then feel free to contact us with your questions, we are more than happy to help.

Sterilght UV lamps S810RL

UV Lamps

Discover our range of genuine replacement lamps for UV units to fit: Atlas, Wedeco, Viqua, Trojan, R-Can, Luminor, TUV/Philips and more. If you can’t find the replacement lamp you need please contact us for help.