How to Install a Reverse Osmosis Water Filter at Home

Written by: James Smith

Updated: April 10, 2023

We explain how to install a reverse osmosis water filter in your kitchen. We also tell how to recharge a faulty water tank.

reverse osmosis installation

Do you find that you buy lots of filtered or bottled water or are you just in general worried about the quality and safety of your tap water?

If so, a reverse osmosis water filter could be an excellent investment. It’s probably the most effective form of home water filtration available and very reasonably priced too.

If you are concerned about paying out too much money to have a fancy system installed, and are particularly handy at DIY, you could try carrying out your own reverse osmosis installation.

A simple system could cost you as little as $150 to $300, with an additional maintenance fee for replacing the filters.

In the following post, we are going to look at how to install a reverse osmosis system.

RO instructions to install

Before we get down to the nitty-gritty, let’s cover the basics.

A reverse-osmosis system removes chemicals and pollutants from your water supply, separating them and directing the waste down the drain. The most common form is the Point of Use (POU) system which is installed under the kitchen sink.

However, there are more durable Point of Entry (POE) systems that filter all household water. You can see our guide to whole home reverse osmosis water filters here.

RO water filtration is incredibly effective and will remove pretty much all undesirable particles from the water. The only contaminants that it struggles with are bacteria and viruses and for those, you’ll need a UV water filter. But, these contaminants shouldn’t be present in chlorinated city water anyway.

However, there are a couple of downsides….

It wastes water as part of the filtration process, and the water flow rate can be slow.

If you still want to proceed, let’s get started.

RO water filter installed by plumber

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Tools and Materials

Before we discuss the different steps involved in how to install reverse osmosis systems, you need to make sure you have the available tools and materials to hand,

  • Screwdriver (4-in-1 variety)
  • Wrench (adjustable)
  • Sharp utility knife
  • Reverse osmosis filter system
  • Low-pressure tire gauge

Time it Will Take: 2-hours approximately


You need to start by taking the reverse osmosis filter assembly and hanging it on either the side or back wall of the sink base (or close to the location of the sink in your basement) at the specified height as outlined in the instructions that came with the filter.

You’ll be surprised at how big one of these units is, so make sure there is plenty of space. Make sure there’s room to easily change the filters when the time comes too.

Now, turn off both the hot water and cold-water shutoffs and install the saddle or tee valve that came with the filter unit.

Next, take the utility knife and cut the water supply line, the one with the color-coding, so that it can’t get kinks and is above the base of the cabinet. Take the plastic tubing and fasten it to the supply valve.

Undersink RO installation

You can now shorten the waste and supply lines that run to your faucet, to reduce the amount of tubing. However, don’t shorten the large black waste line for the time being.

Take the lines and attach them to the fittings found on the faucet’s base. Those black waste lines are fed through the faucet’s base to ensure they are always above sink backups when they occur but are not connected to the supply.

Now, secure the faucet to your sink and install the adapter for the drain line underneath your sink’s basket. Shorten the waste line to allow it to flow downwards without any loops and then press it inside the adapter.

Next, take the storage tank and set that in place and install the final water line. You now have a reverse osmosis filter system in place.

Before you use it, you will have to follow the manufacturer’s instructions regarding the sterilization of the system and filling it up with water.

Recharging a Reverse Osmosis Holding Tank

If you find that your water filter unit is not delivering the same volume of water that it once did then there could be a problem with your holding tank. 

However, first, you should check the membrane and filters.

reverse osmosis tank

If you have changed them though, it could be that the holding tank is leaking or undercharged. The tank relies on a standard tire valve stem that loses air over the course of time. Once the pressure starts to drop, the bladder is unable to push quite as much water out.

You need to first check the pressure. You can do this using a tire gauge (low-pressure model).

Turn off your water supply to the reverse osmosis system and shut the valve off at the holding tank’s top.

Now, disconnect the tank valve tubing and dump any water left in the tank, out. Next, check the pressure by unscrewing the cap then inflating or deflating it with a tire pump to the standard pressure as outlined by the manufacturer.

When you’ve finished, reinstall the holding tank, tubing and switch the water back on.

Wait until the tank is completely full and then check the pressure again. Wait a couple of days or so and then check the pressure once more.

If you find that the pressure is reading the same, then the problem has been solved and you will not have any issues with how much water is pumped out by the system.

However, if the tank has still been losing pressure, you may have to first replace the valve core, and if that doesn’t work, you may have to replace the whole tank.

Hopefully, we have shown that if you are interested in learning how to install a reverse osmosis system, it is a relatively simple process to follow. Of course, if you are not confident in messing around with the plumbing system in your home and still want to benefit from an RO water filter, you will need to hire a professional.

Either way, whether you do it yourself or have a professional carry the work out, you will get the benefit of clean, pure and healthy filtered water, reducing the amount you spend on bottled water and the amount of plastic waste you generate.

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About the Author James Smith

James is the chief water geek here at His mission is to empower the consumer and allow people to take control of their health. His passion for water health is contagious, hopefully unlike your tap water!

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