Step-By-Step Guide: How To Install A Reverse Osmosis System Under Your Sink

Step-By-Step Guide: How To Install A Reverse Osmosis System Under Your Sink

A reverse osmosis water filter is the perfect way to help remove arsenics, sodium, copper, lead, nitrates, and other unwanted particulates from your water. Using pressure to push the water through pores, the technology and price behind a device like this is not overly complicated or pricey. In addition, it can be surprisingly simple to install a reverse osmosis water filter under your sink with the right preparation.

The following guide is your DIY resource for installing an under-kitchen water filter in your home. Please be aware that if you’re installing a whole house water system, such as a softening system or reverse osmosis filter, professional installation is recommended.

What You Will Need

First you will need your reverse osmosis (RO) filter system, which should be purchased with its intended use in mind and be capable of fitting under your sink. You get what you pay for with these systems, and considering that they will provide the drinking water for your family for years to come, we recommend choosing a high quality RO system rather than price shopping for a bargain.

Many different companies sell these devices with this particular intended use in mind. In addition to the reverse osmosis filter system, you will also require a low-pressure tire gauge for later in the installation. Along with these components, make sure you have an adjustable wrench/spanner, a utility knife, and a 4-in-1 screwdriver, as they will help in installing components.

Again, this is only a DIY guide however if you have any concerns for your safety we strongly recommend you hire the services of a professional local plumber.


1. You Will Want To Mount The Water Supply Feed

More often then not the filter assembly will hang either from the side or back wall under the sink itself. Turning off the cold and hot water shutoffs, you can then carefully install the saddle or T valve that will come with your reverse osmosis water filter. After that, push the tubes into the inlet valve. Be sure to tighten by hand, and then with an additional half turn using a tool. Make sure that you do not make this connection too tight.
The following video will guide anyone unsure of how to locate the shutoff valves:

2. Your Next Step Is To Attach The Sink Mixer

The next thing you are going to do is to feed the water supply lines to their new destinations. This includes the line supplying water, as well as the two waste lines. Going through the gasket as well as the faucet base, it may take a little bit to ensure that everything is going where intended. In addition, the waste lines have no connection to the supply, but should be run through the base of the faucet to stop backups. As an additional note, be sure to cut off any excess tubing that is not required when attaching to the sink faucet.

3. Carefully Attach Drain Line Connector

You will next want to carefully attach the drain line connecter to the bottom base of the sink.

4. Finish By Mounting Storage Tank

The last few things you will do involve carefully mounting the new reverse osmosis water filter to one of the walls below the sink. In addition, you will want to install the final, main waterline in.

5. Clean Everything

With everything set up, be sure to carefully check connections and make sure nothing is loose. With that taken care of, clean and disinfect the various parts of the setup, including areas that connect. Finally, you can careful turn the water back on and test the system for yourself. If any problems arise, then review the instructions given with the reverse osmosis water filter.

Finally, don’t forget to maintain your RO system just like you would maintain your hot water system to avoid having to deal with replacement costs. One thing you can be sure of is that once you go reverse osmosis, you’ll never go back to regular drinking water!

For more water saving tips and water management advice, visit our homepage or contact us with any questions that you may have!