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Ultra Violet Sterilisation

Ultra Violet Sterilising Systems

Quick Introduction

Our UV systems are ideal for treating private water supplies.
Ultra Violet water filters are highly efficient at killing bacteria, viruses and other micro organisms that can be found in un-treated water.

There's an easy guide just below. But first here's some basic information on UV filtration.

I searched tirelessly over the Internet for a company to supply water treatment for my spring water which was very close to failing the annual tests. Many companies didn't bother helping with queries. And with others the equipment was expensive.
UK water filters spent time with me answering all my questions and sorting out the right equipment which was better than anyone on the marketI just want to put on record what a find this company is and their staff. Well priced products that do the job brilliantly and excellent service.  I'm very impressed. Andrew Clarkson

The way the systems work is by channeling water through a chamber which is flooded with Ultra Violet light.

The UV light shines powerfully through water, hitting any micro organisms and immediately destroying their cell's DNA thereby making them harmless.

The UV bulb looks like a fluorescent bulb (ie long and thin). It's dangerous to look at directly so it sits inside an enclosed chamber.

Typical Uses for UV Systems

You would need a UV system if you have a private water supply ie get your water supply from a well, borehole or river etc.

This is called "raw water" - ie any water that hasn't been treated by a municipal water company.

Your Guide to UV Systems

Choosing The Right UV Unit

High vs Low Quality UV Water Filters

Solar Power 12V DC and other non-mains electricity sources

Ultra Violet filters selection table

See all our UV units


Other Important UV Info

Pre filters - a must have

When to turn off your UV lamp

How much electricity does a UV use / Costs

Frequently Asked Questions


Taking Action

Prices and Ordering

Contact our UV specialists

Need a Replacement UV Bulb? Click here 

Choosing the Right UV Unit

How to Get the Right UV Unit for Your Needs

The main criteria you need to consider is what size unit you need.

The main factor here is the flow rate of your water.

You may also need to consider what electrical power you have available ie are you on mains or off-grid?

When you have established these, please refer to your UV filters selection table.

The Importance of Choosing a High Quality UV Unit

To choose the best UV for your needs you also want to make sure it is a high quality unit. This is because you want to make sure the UV you are using is reliable.

If the UV unit fails you might, at best, end up with a bad stomach.

At worst - for example if you ingest micro organisms like cryptosporidium - you could have serious health problems that last for several months or even longer.

High vs Low Quality Ultra Violet Water Filters

As stated above you need to buy a well made, high quality unit and avoid low quality UV filters.

Some of the differences are:

A low quality unit has no inbuilt warning system and / or no lamp-life count down indicator - which gives you a pre-warning that the lamp needs replacing.

Low quality units simply stop working, leaving you with a sudden problem of no safe, filtered water.

How Can You Tell Good from Bad Quality UVs?

Notice that we say "low quality units". We don't say "low priced" because sometimes these low quality cheap units - often imported from the Far East, India or Eastern Europe - are sold for a higher price than the better ones.

As a website - not a shop that needs to cover its high costs of rent, utilities and rates - we can offer our high quality UVs at a reasonable price.

More Benefits of Good Quality UV Systems

Our high quality branded UV systems have high frequency electronic controllers to start up and run the lamp / bulb.

Lower quality UVs tend to use old style "choke and starter" circuits to run the lamps.

The former are much more efficient thereby reducing running costs.

They operate the lamps more effectively giving a better and more stable UV output. This helps prolong the life of the lamp in operation.

Ironically some lower quality UVs use well-made lamps supplied by trusted manufacturers like Phillips. But even these will suffer from the old style choke and starter circuits. The lamps won't work nearly as well. And they won't last as long.

Considering that a UV lamp costs around £100 plus to replace, buying a cheaper unit will end up costing you more in the long run.


"I have dealt with this company for a few years now and they have gone above and beyond to help me. They keep in contact and remind me when my filter is due. Would recommend them every time." Independent Review by Elaine

Solar Powered UV 12V DC units and Other Non-Mains Power Solutions

For sites that do not have mains power available, we can offer three sizes of UV units to run from 12V DC power supplies.
These units provide disinfection across a range of flow rates from 9.5 L/min up to 22.7 L/min at a dosage of 30 mJ/cm2.

(22 litres a minute is more than enough for an average size home).

The highly efficient lamp controller provides constant output current to the UV lamp as well as giving the user a visual ‘lamp on’ indicator.

Basically you hook up your alternative power supply to a standard unit with a different controller on ie you would be looking at wiring your solar panel directly into the ballast.

Please note that if you are "off-grid" you are well advised to treat all the incoming water.

While disinfecting the drinking water alone is much better than nothing, consider that you can get eye infections from washing... stomach infections from brushing your teeth... and children tend to drink water from any tap...

Checkout our customer Rob’s great video on how he set up his off-grid, stream-fed water system using our UV and prefilter (plus water tanks and a pump etc)  

(and his nice mention of our good service when there was an issue

Our Off Grid UV Models

9.5 Litres per minute / 12V UV - Very Small / Campervans etc

15 Litres per minute / 12V UV - Smallish Homes

22 Litres per minute / 12V UV - Larger homes


Please ask us for further details on UVs for your private water supplies

UV Filter Selection Table

Max Flow Rate
L / min
Typical Use
Power Unit Model Link
Feeds a drinking water tap
Small cottage
Average House Up to 4 Beds. Best Seller
5 beds plus house
5 to 6 beds plus house
6 beds plus house
Large property
79 plus
Very large / Commercial

Other Important UV Information

Pre Filters

All UV water filters should have a suitable pre-filter to remove any waterborne particles or debris.

These particles can create a "shadow" behind which some micro organisms, like bacteria, might be able to hide. This prevents the UV light neutralising them.

Your recommended pre-filter for each UV model depends on your local water quality.

All our UV units are supplied with suitable pre-filters.

We can advise you on this and all other aspects of UV filtration. (Please contact us)


When to Turn off Your UV Lamp

UV Bulbs/lamps are designed to be left on all the time.

Turning the bulb/lamps on and off regularly will greatly shorten its life by 3x and / or cause premature lamp failure.

On average the UV bulb/lamp loses between 4 to 6 hours of lamp life every time it is turned on and off.

Definitely don't switch off your UV lamp/bulb on a regular basis eg not daily or weekly.

However if you are going away for a long periods you can weigh up the cost of the electricity used vs the cost of the new bulb.

For holiday homes, where you know that you are not going to be there for, say, 6 months at a time, we would suggest switching the unit off to save electricity and lamp usage i.e. you would then get 2 seasons out of a lamp - rather than one.

(A lamp left on would need to be changed every 12 months regardless of how much water had gone through it).
When you return to the holiday home, you should then re-sanitise your whole system with bleach (just like when you installed your UV unit in the first instance).

If you are only leaving the house for a few weeks, then it would probably be easier to leave the unit on.


"I have been using the water filters from UK Water Filters for some years now, and found both the filters and the service from the company to be excellent." Independent Review by Frongog

How Much Electricity does a UV Lamp Use?

Depending upon the model of the unit, the power usage varies between 30 Watts to 48 Watts.

A kilowatt hour is the use of 1000 watts of electricity in an hour.

Therefore, a 20W bulb takes 50 hours hours of use (1000 watts (ie 1KW) divided by 20 = 50 hours).

At the time of writing a 30W UV light costs about 50 pence per month to run.

Cost of Ultraviolet lights / lamps / bulbs

Figures from this UK power usage calculator

When and Why to Change Your UV Lamp

Note that UV Lamps do not burn out and suddenly fail / stop giving light. Instead they "solarise".

What happens is that over time the lamp's effectiveness decreases to about 60% of a new UV lamp.

But you can't see this change.

All you can do is judge how long the lamp's been in use for.

The maximum life is one year. After this time the UV light given out by the bulb will drop to below 30 mJ / cm2 - the minimum dose needed to kill micro-organisms.

So make sure you change your UV lamp/bulb every year without fail.

If you're not sure how long a lamp has been installed for - change it!

Frequently Asked Questions

Question: How long does the lamp last for?

Answer: You should change it once a year. Even though the lamp might still seem to be working, the UV output decreases over time. Don't risk your health by saving a few pounds. Changing at 12 month guarantees full safety.

Question: What happens if the flow exceeds the max flow rate?

Answer: There are no flow restrictors on the standard range of units. If you exceed the recommended flow you will end up with less treatment.

So it's best to overestimate your usage. If you are concerned about exceeding it then simply add a flow restrictor. These can be purchased quite cheaply online.

Question: Can I treat Hot water with my UV filter?

Answer: The UV filter should normally be connected only to the cold water supply. However it can handle hot water up to 40 degrees centigrade.

Question: Where can I install the UV system?

Answer: The UV is designed to be used indoors and should be installed in a cool, dry, well-lit area.

Leave enough space for changing the lamp and quartz sleeve - at least one full chamber length so you can pull the lamp and sleeve out of the unit.

Your UV unit should always be installed closest to the point of use. It should flow directly from the system to your tap - don't leave the water sitting in a tank or bacteria might take hold.

Question: Do I need electricity?

Answer: Yes you need a simple electrical power supply with normal plugs - ie no special connection is required. However, if you are "off grid" we can supply 12 Volt units that work with solar power and other alternative energy sources. See UV with non-mains electricity

Question: Do I need a pre-filter?

Answer: Yes always. These remove any waterborne particles or debris which can create a "shadow" where bacteria etc can hide as they flow through the UV chamber. If the UV light doesn't hit them the bacteria will survive,

The type of pre-filter you need depends on your UV model and your local water quality. Please contact us for advice.

Question: How often should I clean the Quartz sleeve?

Answer: The quartz sleeve holds the UV lamp and separates it from the water. It needs to be kept as clear as possible so it doesn't block the UV light. How often you need to clean it depends on your local water quality.

A good idea is to remove the sleeve after 6 weeks and then 12 weeks of operation to inspect it. If it's already discoloured then you need to add more pre filters. Otherwise, give it a clean every 12 months ie when you change the bulb.

Question: How do I install the unit?

Answer: This depends on the exact model. All our UV filters come with full, comprehensive installation and servicing instructions.

Some Customer Questions and Answers


We have an off-grid cottage that sleeps 5 people. Water will be coming from a small moorland stream above the house via about 400m of pipe.

There is 35m of head.

I doubt the flow rate out of the stream will be enough for filling baths etc and I really don't want to empty the pipe, with risk of air-locks afterwards, so we will need a cistern somewhere. At the moment I have about 80 gallons of water in a couple of loft tanks.

My feeling is that I should use the two loft tanks separately, one as a header for the hot water and one as a header for cold. That way the water can be UV sterilised in the feed to both tanks (each will have its own float valve) and there won't be any risk of the hot header feeding into the cold taps.

This means that the UV system doesn't have to cope with a huge flow rate, just with the flow rate through a couple of float valves.


Our recommendation is that though it is obviously easier for your particular application, you should not install UV treatment before any storage devices.

UV treatment has no residual effect on water and header tanks are among the best places for bacteria to grow and enter a particular supply. Even completely air tight water tanks can have bacteria growing in the air space between the tank and water.

Because of that we always recommend that this type of equipment is installed on the outlet side of any tanks.

The UV filter can handle hot water up to 40 degrees centigrade.


I have a small cottage with no mains electricity. I am hoping to have a picohydro (ie small hydroelectric power) system that will make enough electricity to run the UV bulb. Can I run the UV directly off a 12 Volt or 24V supply. Obviously the lower the power the better.


For your supply we would recommend our 12 Volt unit. (24V systems are usually used on Boats and Yachts).

Please see the section on Solar Power UV Other non-mains electricity sources


I want to fill up a storage tank on an off grid cottage for a few minutes a week (using a 12v battery). We want to save power by only turning on the bulb while we fill up the water tank.
Will that reduce life of the UV bulb? (I assume we need to change the bulb yearly regardless of how much we use it... but will turning it on / off frequently break the UV bulb sooner?


The bulb would be fine. In fact, in this case, you would only need to change the bulb after 2 years - compared to having a bulb running constantly for a year. The actual work time you get out of it is severely reduced. But the 2 years takes the on and off switching into account.

One thing we would like to mention here is that it'd be almost worthless UV'ing the supply when it's getting stored in a water tank right after then UV treatment. Even completely air tight water tanks can have bacteria growing in the air space between the tank and water, and the bacteria will be reintroduced there.
This is why we recommend putting a UV unit on the outlet supply. But then your unit will be turned on for a lot longer than you wanted....

Prices and Ordering

It's all about the flow rate! So the first step to find out the cost is to find the flow rate.

You can see all our UV units and their maximum flow rates here

But when you're drinking from a non-mains water supply it's important to get it right.

So, to ensure you are getting the right system for your precise needs, please feel free to contact us for further information - either on the phone during UK office hours, or anytime via the quick enquiry form below.

We will get back to you very soon.

"I have been dealing with Uk Water Filters for more than six years, I have always found them to be one of the most conscientious of company's eager to help with queries and information. the product and delivery service are second to none and other online companies could learn from their business ethics and their service!!! Oh! and did I mention they are extremely competitive Regards Griff" Independent Review by Griff Worcester


Your Money Back Guarantee

Need advice?
Please call us on
020 8761 6611

Need a Replacement UV Bulb? Click here

Guide to UV Systems

Choosing The Right UV Unit

High vs Low Quality UV Water Filters

Solar Power 12V DC and other non-mains electricity sources

Ultra Violet filters selection table

See all our UV units


Other Important UV Info

Pre filters - a must have

When to turn off your UV lamp

How much electricity does a UV use / Costs

Frequently Asked Questions


Taking Action

Prices and Ordering

Contact our UV specialists

Need a Replacement UV Bulb? Click here 





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