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Full Guide: The Best Reverse Osmosis Water Filter (2021)

The Best RO Water Filters

When considering buying a reverse osmosis water filter, it is important to understand that they are not the same as water softener systems or other water filters.

(They do ‘soften’ your water, but this is a happy by-product of the filtration process).

Reverse osmosis water filters are very high grade filters - the best available.

(Other high-purifying techinques like distillation are usually not very practical - they require a lot of electricity and long term can be detrimental to your health. eg some bacterial strains aren't removed. Distillation also doesn't remove most volatile and semi-volatile organic compounds).

They use a high tech membrane to separate water molecules from larger ions or contaminants that often get into the water system.

Reverse osmosis filters work slowly and need a tank to hold the treated water so that it is available for you on demand.

The size of the system required (and therefore the tank) is dependent upon the needs of your household.

Reverse Osmosis filters remove a wide variety of harmful chemicals and other pollutants from your water.

Depending on your location, you could have mercury, copper, arsenic, lead, chromium and various nitrates in your water supply, plus the foul-smelling chlorine and the calcium that attaches itself to your bathroom and kitchenware metals.

Very few standard water filters are capable of removing these toxic minerals, bacteria and other deposits with the efficiency of a reverse osmosis system. Fewer still can remove them all.

To help you decide if an RO system is right for your home, you should consider:

- Your budget
- Your home environment
- The space needed to install your system
- Water pressure
- The needs of the household

The first thing you should do when considering which system is best for you is to work out what you need.

Whole House Reverse Osmosis

First a quick note on these because we get asked about them a lot: A whole of house reverse osmosis installation is possible. But it's not practical.

You'd need a large reverse osmosis unit and these are designed for commercial applications - not resdiential.

A high level of maintenance is required - it's not unlike having a swimming pool (but even more complicated). It requires regular checks / monitoring by somone who knows what they're doing

Normally you would get an easier solution like Ultra Violet filtration for all the water in the property. Then Reverse Osmosis at the final "point of use" ie drinking stage.


Those with specific needs due to the very poor quality of their water supply, or those whose home is supplied with well water or from a borehole would probably need an Ultra violet filter.

In addition to the upfront cost of the RO unit, you also have the additional cost of replacing the cartridges or media and the membrane used by RO filter systems.

The cost or replacement is dependent upon your usage. The more water you use (and therefore process through the RO filtration system) the sooner you will have to buy replacements.

Another factor is the issue of waste water: sometimes less than 30% of the water used in a reverse osmosis system is recovered for use. That means you will be ‘wasting’ 70% of the water supply coming into your home.

While the costs of waste water can be less than you might think - check this article on the real costs of RO waste water - this additional cost should also be accounted for in your budget when choosing the best RO system for your home.

Home Environment

Having Enough Space

Domestic RO units usally go under the sink and will fit a standard kitchen sink unit.

You will need a tank to hold the water that has been filtered - these come with the system.

Reverse osmosis works slowly so the more water you require, the bigger the tank you will need to hold the water after filtration.

So if you need a larger tank than usual you might need to create more space for it under the sink.

These are the dimensions for our standard sized domestic / residential revers osmosis unit

Another option some householders choose is to install their RO water system in a separate room. This is easily done by simply having longer tubing. (If you need extra tubing from us simply ask us after buying a unit and we will provide a few extra meters gratis - within reason.)

Water Pressure

A Reverse omsosis water filter requires a certian level of water pressure to work.

Most UK homes - about 90% - have high enough pressure.

Before buying a unit you should check that the water pressure in your home is adequate to support a reverse osmosis system. Otherwise you will need to come back and buy a pumped RO unit - which would waste time and effort (ie sending the wrong unit back for a refund - assuming your seller offers a refund! (We do).

Here's more about your house water pressure and reverse osmosis

Reverse Osmosis System for Home

Depending on your particular requirements you may decide that you need RO water for drinking plus a whole house softener system for your bathing and laundry needs.

Combining an RO system with a water softener or filtration system will give you two benefits:

- You will have the best quality drinking water from your RO system

- The water softener/filter will remove the scale deposits that make cleaning and bathing a chore and often cause problems by clogging home appliances.

Such a set-up is not a complex installation and reputable companies will be able to advise you on the combination of systems that best suits your household’s needs.

For example we offer this RO for drinking water and this whole of house filter and softener

Reverse Osmosis Water Dispenser

There are two basic options for getting the purified RO water from the filter

- A separate tap used for RO drinking and cooking water
- An integrated ‘three-way’ tap.

A separate "small tap" comes as standard with our Reverse Omsosis filter units. These sit on the side of your sink and deliver only filtered water.

Or you can get three-way tap that gives you hot / cold and filtered water at your kitchen sink.

Best Countertop Reverse Osmosis System

For those who prefer to have a countertop RO system, there are several high-quality options.

Countertop RO systems plug into a power socket and need a cold-water supply and a connection to the drain for wastewater.

Quality countertop systems are made with a ceramic element to avoid the heavy metal extraction caused by metallic elements.

A countertop system will give you the option of instant RO water that is hot, cold, or even warm. You can make your tea or coffee using the hot water in the system and know that it will be made with healthy RO water.

Many health-conscious customers have chosen to combine a countertop reverse osmosis system (for drinking water and tea/coffee) with a water softener system (for bathing and laundry use).

Common Questions about Reverse Osmosis Systems

Below is a list of common questions asked by householders who research reverse osmosis water filters.

Are reverse osmosis filters worth it?

Everyone will have their own opinion about how much they can benefit from purchasing a reverse osmosis filter.

Some people smoke and others exercise. Some people buy health food and avoid takeaways, while others eat junk food and drink a lot of alcohol.

Reverse osmosis systems are usually purchased by people who want to drink pure, quality water that is up to 98% contaminant free. If you fit into that category, the purchase of a reverse osmosis filter is worth it.

Are all reverse osmosis filters the same?

Like all products, some are well made with quality materials and others are made cheaply with materials that will wear out quickly or not do the job that they were ‘designed’ for.

Your best bet is to buy a reverse osmosis filter from a reputable UK company (hint, hint :) that offers a guarantee and has a dedicated customer service channel. You want to be able to speak to a real person, not an internet server.

Always check references online to make sure you are using a company with a good track record for customer care.

How much does a reverse osmosis system cost to install?

Most domestic reverse osmosis drinking water systems are easy to install. Any householder who is relatively ‘handy’ could do it.

You should receive full instructions on how to install your system with the product. If you are wary of installing the system yourself, you could get a handyman or a plumber to install it for you. It is a very easy job for a plumber.

Whole of House reverse osmosis systems should be installed by a plumber. The price of installation will be determined by the type of system you choose and the complexity of your installation.

You should seek help from a reputable supplier to estimate the costs for your installation.

How much wastewater Is produced by a reverse osmosis system?

There is no getting around the fact that reverse osmosis systems waste a lot of water.

During the filtration process, purified water is stored in your tank ready for use, but the remaining ‘waste’ water is discarded. This is obviously uneconomical. However the costs of waste water are much less than commonely assumed - read more on the costs of RO waste water

But there is an environmental cost to consider here - though it's quite easy to mitigate this by re-directing the wastewater for suitable use elsewhere in your home & garden.

What does water produced by a reverse osmosis system taste like?

Water has no taste, so it is hard to describe water that has been filtered by a reverse osmosis system. Many say that it tastes ‘clean and fresh’.

A good way to think about what water filtered with a reverse osmosis system tastes like is to think about what it doesn’t taste like. Your water will not taste:

- Salty (because the sodium has been removed)
- Bitter (because the magnesium is gone) or
- Milky (because you no longer have calcium in your water system).

Do I need a reverse osmosis system with a UV light?

Reverse osmosis water systems will filter out up to 99% of the harmful chemicals in your water. This means the system kills contamination that has been dissolved in your water supply.

However, RO systems will not kill microbiological bacteria.

The good news is that most people in the UK will not have microbiological bacteria in their water supply because governments set stringent controls to ensure microbiological bacteria do not make it to your tap.

That bad news is that householders who are drawing their water from a well or bore might need to use a reverse osmosis system with a UV light to ensure they have safe, clean water.

The best option in these cases is to have a separate UV filter for the whole fof the property - so there is no risk of swallowing small quanties of infected water in the shower or while brushing teeth etc

Is reverse osmosis water bad for you?

It is wrong to say that drinking reverse osmosis water is bad for you. Those who say that probably have an agenda.

However, there are some things you should be aware of when deciding whether to buy a reverse osmosis water filter. There are two potential, albeit easily solved, problems:

- Your water will be more acidic

- Minerals essential to the body such as calcium and magnesium will be lost in the reverse osmosis process

These two potential problems have two simple solutions:

- To solve your acidity problem, quality reverse osmosis systems - like ours - include a re-alkerising cartridge (sometimes called a pH adjuster or neutraliser) to counter this

- Good systems will also add a re-mineralising filter to your system to regain the lost minerals. (You should also be aware that a healthy, balanced diet will also heavily reduce the chance of any problems. We do not get calcium and magnesium only from water.)

The key to avoiding any problems is to buy a quality product from a reputable supplier who can give you sound advice and answer all of your queries.


Choosing the right RO filtration system for your home is a difficult one and should not be undertaken without significant research.

Buying the wrong system can be stressful and expensive.

Good quality RO systems are not cheap, but they do give you the peace of mind to know that you are giving your household the best quality water.

The key when choosing the right system is to understand your household’s needs.

Consider your budget, get good advice from a reputable company with a track record of customer care, and chose a system – or a combination of systems – that will give your household what it needs.

Drink to your health

Our water filter systems can remove harmful pathogenic bacteria, cysts, parasites, and unhealthy chemical contaminants such as Chlorine, while at the same time leaving in the essential minerals your body needs.


Save money on bottled water purchases by regularly usingfiltered water. Get your highest quality water filters at the best price here.


We supply the widest range of water filters for any needs - residential or commercial.