Bottled water quality. From £1.96 a week.

The Gold Standard. Extremely powerful purification: Removes 200+ contaminants — chlorine, fluoride, microplastics, heavy metals, pesticides, bacteria — then uniquely restores natural minerals so it tastes as good as it performs.

No plumber needed · Easily install under your sink in an hour · Everything included

Removes 200+ contaminants

Fluoride, lead, microplastics, pesticides, E.coli and more

Re-mineralised as standard

Restores natural minerals — better tasting than most RO systems

3-year warranty

Plus 90-day money-back guarantee & free returns

Same-day dispatch

Order before 4pm for same day despatch — free delivery included

Free lifetime support

UK-based team — we care! and always reply as soon as we can

31p a day to run

Less than a third the cost of a daily bottle of water. Reduce plastic waste!

£287 £378 Save £91 (24% off)

That's £1.96/week — inc. VAT & free delivery

100,000+ customers served 25+ years in business Trustpilot's best rated UK water filter company

My overall experience has been amazing ! My RO water filter arrived really quick. Ed was a dream in helping me with any queries. I can't recommend this company highly enough. I absolutely love my filter. Thank you! Rachel J. - verified buyer

If you want to remove the widest range of problem contaminants from your drinking water - like pesticides, bacteria (ecoli, cryptosporidium etc), microplastics, microfibres, heavy metals, fluoride - and many other pollutants - Reverse Osmosis is, without question, your easiest and best solution.

Plus you get great tasting, healthy water!

Read on for full details, plus useful information and tips on what to watch out for when looking for an RO filter.

How the Filter Fits into Your Kitchen

The filter is designed to fit easily under a standard kitchen sink.

To serve your fresh, purified drinking water you can either get a stylish, small extra tap on your counter top, which you use when you want to drink. (This is supplied as standard with your kit).

Or you can get a "three way tap" - which gives you hot / cold and filtered water. (Here's the three way tap we can supply you with - but the system can be used with any make of similar tap.

As you may already know, Reverse Osmosis filters are usually expensive. You can easily pay £400 plus.

Why Our RO System Costs Much Less than Others

Without us having to cut corners

The honest answer has two parts.

First: we don't add filter stages you don't need.

Some suppliers market their RO systems by the number of "stages" — five-stage, seven-stage, even nine-stage.

More stages sounds more impressive.

But the filtration science doesn't support it.

A well-engineered RO system needs

a good pre-filter (we give you two),
the membrane
a remineraliser/ realkaliser filter
a post-filter (to polish the water before it reaches your tap.)

That's five stages.

Everything beyond that is either redundant, marginal in benefit, or added specifically to justify a higher price.

We know this because we've been in water filtration for over 25 years. We understand what each stage actually does — and doesn't do. So we build the system around the science, not around the price tag. (More info here on unnecessary RO "stages")

Second: we sell direct, online only.

No showrooms, no sales reps visiting your home, no retail margins. Those costs don't make the water any cleaner, but they do make the unit considerably more expensive when other suppliers pass them on to you. We don't.

The result is a system that is, in our assessment, technically superior to many units sold at £400–£500 — at around half the price.

The 3-year warranty and 90-day money-back guarantee are there precisely because we're confident in that claim.

Read More

Pros and Cons of Reverse Osmosis

What about "Wasted Water"

Important Note about Acidic water

What about the Minerals?

List of Contaminants Removed by Reverse Osmosis

Installing the System

Replacing the Filters

How Reverse Osmosis Works

What are Reverse Osmosis Stages?

Summary of Features

Pros and Cons of Reverse Osmosis

Pros: RO filtration gives you very high quality water. It removes just about every contaminant you can think of.

Cons: They are more expensive than a standard water filter.

Is it Overkill?

To be honest British tap water is usually good quality. Many people simply want to remove basic contaminants like chlorine in order to get "mineral water" quality for a fraction of the price of bottled water.

Many dangerous contaminants, like bacteria, are taken out by the water treatment plants.

However, other contaminants can get left in the water which RO will remove and a standard water filter won't.

The main reason for choosing an RO unit would be if you wanted to remove a specific contaminant from your water, for example fluoride or hormones or microplastics - among many others.

Or perhaps you would like an RO to help with an allergy or other medical condition.

Otherwise, if you are simply looking for a good quality water filter, you might be best opting for a less powerful but good undersink water filter.

This is because the initial purchase and ongoing cartridge renewal costs of a standard are much lower than an RO.

If you do want an RO, please note that we sell very high quality ones at about half the price of many other suppliers.

Be wary about cheaper products though. While ROs do remove nearly all micro-organisms, cheaply made and/or deteriorating parts can greatly increase the risk of contamination through tiny leaks within the system.

UK Water Filters have always offered a great service with excellent after sales service. This is a great product which we have used for many years now. It pays for itself over and over. Steve - verified buyer

The Issue of Waste Water

As part of the Reverse Osmosis filtering process about 70% of the water is rejected / wasted.

While this is only lost from your drinking and cooking water - i.e. not all the water you use in your home - in these times of water meters and general environmental awareness, this may be off-putting.

The "waste / rejected water" is automatically sent down the drain. However, you could recycle it e.g. for garden watering.

(You can read more details about this in the quick article about What are the added costs of wasted water with your Reverse osmosis system

Important Note about Acidic Water

Why We Include a Re-Alkaliser as Standard

Reverse Osmosis is extraordinarily effective at removing contaminants — and that thoroughness has one side effect worth knowing about.

Natural tap water contains dissolved minerals, particularly calcium and magnesium bicarbonates. These act as a natural pH buffer, keeping water slightly alkaline (typically pH 7.5–8.5). When RO removes them, that buffering effect goes with them, and the filtered water becomes mildly acidic — typically in the pH 5.5–6.5 range.

This isn't dangerous, but mildly acidic water can taste flat or slightly sharp, and most water quality guidelines recommend drinking water that is neutral to mildly alkaline.

Our solution is simple: we re-add what RO removes.

Every system we supply includes a re-alkalising mineral media cartridge. As the purified water passes through it, natural minerals are reintroduced, raising the pH back to a neutral or mildly alkaline level — typically pH 7 to 8.

Most UK reverse osmosis suppliers don't include this. We do, as standard, at no extra cost.

(If for any reason you'd prefer the system without the re-alkaliser — for example, for a specific technical application — just let us know when ordering.)

How Much Does it Reduce the Acidity?

This depends on how acidic your source water is. But our re-alkaliser will have a significant effect.

You can expect your pH level to rise to at least 6 or more (pH 7 is neutral. Anything higher is alkaline).

What About the Minerals?

Here's the Honest Answer.

It's true that RO removes virtually everything from water — including calcium and magnesium, the naturally occurring minerals that give tap and spring water its characteristic taste and contribute modestly to your daily mineral intake.

Critics of RO sometimes present this as a serious health threat. The reality is more straightforward.

The actual concern — and why it doesn't apply to Reverse Osmosis

The scientific literature on demineralised water does suggest that drinking it exclusively over long periods, without dietary compensation, could marginally reduce mineral intake.

The more relevant mechanism is that very low-mineral water has a slightly greater capacity to leach minerals from foods during cooking.

Neither effect is dramatic — but they're real enough that the World Health Organisation recommends a minimum mineral content for drinking water, and real enough that we take them seriously.

Which is exactly why we include re-mineralising media as standard.

Before the purified water reaches your tap, it passes through a mineral restoration process that reintroduces calcium and magnesium at levels consistent with good-quality natural spring water.

You get the purity of RO with the mineral profile of bottled mineral water.

This is included in every system we sell, at no extra cost. Most UK RO suppliers don't do this.

What about minerals from food?

A balanced diet does provide the vast majority of your daily calcium and magnesium — your water contributes a relatively small fraction.

So even without our re-mineraliser, the risk from RO water alone would be modest for most healthy adults eating a reasonable diet. But modest is not zero, and there's no good reason to accept any unnecessary risk when the solution costs nothing extra.

So the reassuring facts are:

Fact one: An easy solution to the filtering out minerals issue is to simply re-mineralise the RO purified water before using it.

We do this with a high quality re-mineralising media along with the re-alkaliser media. Problem solved.

Fact two: In any case, a good varied diet with lots of fruit and vegetables should ensure you have more than enough minerals to cope with any risk of mineral deficiency.

I have to say that it has really made me happy the way you deal with people. Gives me hope there could be a better world. Barbara C. - verified buyer

How Hard is it to Install the Filter?

Everything you need is in the pack.

It's very easy to install. No plumber is necessary.

You might prefer to use a plumber. If so, this should be a simple, "one hour callout" job for them at most.

(If you're going to hire someone else to do it, we suggest you use a handyman - they'll probably be cheaper than a plumber - and just as good at what is a very straightforward job).

Otherwise, it is all designed to be done by a householder. Full instructions are included. It should only take you about an hour. You will need a normal electric drill. That's all.

It comes with an easy-fit DIY self-tapping "saddle valve" that pierces your water pipe (works on 12mm and 15mm pipes - ie 99% of under sink pipes.

And we've got friendly (and free) customer support available.

After much research I decided to purchase a reverse osmosis unit from UK Water Filters and have found the product very easy to install and excellent service if any problems - really do know what they are talking about... good after-sales service. Very pleased and great to have fresh tasting water once again. Maggie - verified buyer

Replacing the Filters

Like all water filters, you will need to replace the filters on the system periodically to ensure maximum performance.

Cartridge Replacement Information

Five filters needs to be replaced every: 6 Months.
Replacement code: FRO-DM-UKWF https://www.uk-water-filters.co.uk/products/ukwf-reverse-osmosis-cartridge-renewal-with-remineraliser
The membrane filter needs replacing every 2 - 3 years on average *depending on local water conditions
Replacement code: MEM-RO https://www.uk-water-filters.co.uk/products/mem-ro_reverse_osmosis_membrane_replacement
Running costs per days - approx: 31p
Replacement time / difficulty: Easy; takes a few minutes

Replacement notes:

Your pre filter cartridges and membrane “drop in” to a housing. Tubing "push-fits" into your post filter cartridges. You replace the cartridges NOT the whole housings.
We send you a reminder when it’s time to change the cartridges.

All the required filters are included when you purchase the RO system.

Read about how Reverse Osmosis works

For full performance details of our RO units please click here.

Supplied complete with all fittings and ready for immediate installation - including tap.

Features Summary:

What you get — in plain numbers

200+

contaminants removed

99%+

filtration rate

12L

storage tank included

3 yr

full parts warranty

Filtration

Membrane type	TFC (Thin Film Composite)
Rejection rate	98%+ dissolved solids
Filter stages	4 — no redundant stages
Re-mineraliser included	Yes — as standard

System specs

Production rate	75 gallons/day
Tank capacity	12L nominal (5–9L usable)
Unit dimensions	43.5 × 35 × 12.5 cm
Feed pressure	2.7 – 6 bar

Running costs

Daily cost	~31p per day
Filter pack (×5)	£39.95 every 6 months
Membrane	£79 every 2–3 years

Peace of mind

Warranty	3 years (full parts)
Money-back guarantee	90 days, no questions
Installation	DIY, ~1 hour, no plumber

Everything you need to install the system is supplied
Simple installation no plumber needed
Full instructions included
Easy to use

Reliable operation
Free Technical Helpline to assist with any problems
No Quibble THREE MONTH Money Back Guarantee
Buy with complete confidence
Three year full parts warranty

Compact design
Failsafe flow restrictor
Auto shut-off/on full tank
Five top quality cartridges

ORDER ANYTIME Day or Night 24/7 for NEXT DAY DELIVERY

With FREE Delivery

Immediate Dispatch

Purchase with Total Confidence

THREE MONTH Money Back Guarantee

Click here for delivery information

No hidden extras

If you don't like what you get, send it back for a full no quibble refund.

If for any reason you decide to return your purchase we promise you a no questions asked THREE MONTH Money Back Guarantee. Click here to read the "large print" about our Money Back Guarantee.

PLUS We'll even pay your return postage !

Product Code: RO-UKWF

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Larger High Capacity Extra / Spare Reverse Osmosis Tank 18L

Reverse Osmosis Water Filter System