Reverse Osmosis Water Filter Systems. 

Finerfilters offer a wide range of Reverse Osmosis systems, accessories, replacement cartridges and membranes for a number of applications. Our best-selling domestic and aquatic RO systems see us as a leading supplier within the UK. We are always looking to expand our range, as seen with our brand new Tankless Reverse Osmosis Systems.

Tankless Reverse Osmosis Water Filter SystemsTankless Reverse Osmosis Water Filter Systems

Tankless RO Systems

Domestic Reverse Osmosis Water Filter SystemsDomestic Reverse Osmosis Water Filter Systems

Domestic RO Systems

Aquarium Reverse Osmosis Water Filter SystemsAquarium Reverse Osmosis Water Filter Systems

Aquarium RO Systems

Dental Reverse Osmosis Water Filter SystemsDental Reverse Osmosis Water Filter Systems

Lab & Dental RO Systems

Reverse Osmosis (RO) is a filtration process that creates one of the purest forms of water and can remove up to 99% of all contaminants. Depending on the system, water is pushed through 2 to 3 pre-filters, a membrane and finally through a post-filtration stage which can be DI resin (to reduce TDS down to 0) or remineralising filter (to replace health essential minerals lost in the RO process), depending on its application.

Typically it needs an optimum pressure of 80-90 PSI – so it may also include or require a separate booster pump should you not have the required pressure for it to operate correctly.

Reverse Osmosis (RO) works by forcing water through a semi-permeable membrane that filters molecules down to 0.0001 microns (by comparison, a strand of human hair is 0.8 microns!). That’s fine enough to essentially remove all contaminants in the water, including hormones, fluoride and pesticides.

In fact, people who drink it usually opt for a remineralisation filter to put back some of the good nutrients such as magnesium, calcium and potassium (and make it taste better!).

With an RO system, when the water is forced through the membrane under pressure, only the H2O molecules are allowed to pass through and the remaining water is rejected to the waste line. In a traditional RO system, around three-quarters of the water is rejected and the remaining quarter is pure, filtered water.

Pumped or unpumped system?

Reverse Osmosis works by putting water under high pressure. We strongly recommend checking your water pressure before you buy a Reverse Osmosis System, as adding a booster pump separately, post-purchase is more costly than purchasing a pumped RO system firsthand.


Our pumped RO systems require a minimum of 30PSI (2 Bar) pressure and un-pumped systems require a minimum of 40PSI (3 Bar). Anything below these levels will make the system inoperable. We will always recommend that you purchase a pumped RO system, this is because the optimal operating pressure we recommend is around 80PSI (5.5Bar) and it is very rare that your incoming mains water will have such high pressure. 


It is also much more sustainable to have a pump as this will constantly operate at the pressure that you set, compared to mains water pressure which can fluctuate due to factors such as other people or appliances in your household using water (washing machine, showers etc.) which will cause the incoming pressure to drop.


  • Filters out 98% of contaminants
  • Even removes hormones, fluorides and pesticides
  • The water produced has a variety of uses, including window cleaning, drinking water, aquatics and hydroponics


  • Produces a lot of waste water
  • Requires high pressure to work
  • Takes longer than other water filter systems to produce water


Humans actually get a lot of nutrition from water, but the Reverse Osmosis process is so thorough that it removes essential minerals such as Calcium, Magnesium, Sodium and Potassium along with harmful contaminants. Our remineralising filter adds these essential elements back into the water just before it’s dispensed from the tap. 

Re-mineralising filters can be found on our Six Stage Reverse Osmosis Water Filter Systems or you can install one retrospectively, shop here.

What can I do with my waste RO water?

With a traditional RO system, there is around 3 to 4 times more wastewater produced than there is pure water. Most of the time, the wastewater will go into a bucket and/or be disposed of down a drain. The wastewater is actually highly concentrated in some minerals, which can be very good for plant life – so it’s perfect for watering your garden! 

Please be aware that this water is more concentrated and therefore may need to be diluted with other filtered water before use.

Looking for a Replacement Water Filter for your Reverse Osmosis System? Click here. 


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