How to Install Reverse Osmosis Water Filtration System Under Sink

Water is essential to life. But sadly, we often have to spend money just to have access to clean, potable water, unless, of course, you reside in countries such as Switzerland and the United Kingdom wherein the water that comes out of the faucet is so clean that it can be consumed right away. Buying drinking water does not cost that much but if you think about it, if you buy a bottle one day for an entire year, you will have spent an amount of money that you could have set aside for something else that you want to buy instead! Good thing we can now purify water in our own homes these days simply by installing a reverse osmosis water filtration system ideally right beneath our sinks! 

RO water filtration systems are said to be more effective than carbon black filtration systems and much less expensive than UV disinfectant systems. Another thing that makes reverse osmosis filtration systems ideal for home use is that they are better at eliminating chemicals such as chlorine from water. Thus, they will be of great help to people who live in cities wherein the water that reaches their homes is often treated with chlorine to eliminate microbes. Installing an RO filtration system will take you around two hours at most. Instructions for installation may vary depending on your RO system’s manufacturer and brand, but here you are going to see the general flow of the installation process. 

Materials Needed:

Steps in Installing Reverse Osmosis Water Filtration System Under Sink 

1. Preparation

This part should be done even before you purchase your RO filtration system. Prepare for the installation by deciding where exactly you want to install the unit and make sure that the area can accommodate the entirety of the RO system that you’re planning to buy. One of the components of the system is a reservoir tank, which must ideally be placed on the ground since it will hold water and thus will become very heavy. Also, ensure that there is a cold water line that will bring water into the unit. 

Under Sink Reverse Osmosis Water Filter - Reverse Osmosis System ...
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2. Install the Faucet or Spigot

Decide where you want to put the faucet. It must be a flat surface. Usually, sinks have built-in holes wherein you can plug the faucet or spigot in. However, if there is none, you will need to drill a hole. Mark the area where you plan to position the faucet and drill away! Do this with caution. Once finished, remove metal chips and smoothen sharp edges. Then, plug the faucet into the hole, making sure that it is secured at the bottom by washers and nuts. Attach the quick-connect fitting and tighten using a wrench. 

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3. Install the Drain Saddle

Make a hole on the side of the drain line, then slip the drain saddle in and secure with bolts, while making sure that it is not too tight. Align the hole of the clamp to that of the pipe. 

4. Install the Feed Valve

The feed valve regulates the entry of water into the RO system. When installing this component, make sure that the water is turned off. Remove the cold water tubing and put it in the new feed valve.

Tighten with a wrench and close. Then, attach the cold water tubing and turn the system on. 

5. Install the Reservoir Tank

Put some plumber’s tape on the tank’s threaded top. Screw the tank valve or connector. Do not tighten it too much. It must thread easily. Put the tank in position. 

6. Mount and Connect the Reverse Osmosis Module

Most RO systems are easy to install because each colored tube matches a port on the system that is of the same color. You just have to put them together. Do this for the feed water line, tank line, drain line, and faucet supply line. Gently pull the tubes after connecting to check if they are securely attached. 

7. Install the Filters and the Membrane

These parts will promote the purification of the feed water. To install the pre-filters, detach the filter housing, carefully put in the filter, and put the housing back. Use a wrench to secure the filter housing. To install the membrane, remove the membrane housing, and put the cylindrical membrane in. When done, put the cover back and secure it with O-rings. 

8. Start your brand new reverse osmosis water filtration system!

Go through the entire setup to check if everything has been correctly attached and tightly fixed. Then, ensure that the valve of the reservoir tank is closed. After this, open the feed water valve and the RO faucet. Shortly after, you must see the water moving into the dispenser. Close the RO faucet and open reservoir tank valve so that water flows into the tank. When the tank is full, open the drinking water faucet so that all the water is released. Then, refill the tank again and repeat this emptying process three more times before refilling the tank one last time and using the water for consumption. 

Steps to Maintain Your Reverse Osmosis Filtration System

Now that you have an RO filtration system, you must be loving it. But remember that like any other machine, your unit could eventually have reduced efficiency, particularly if it’s not taken care of. But if you want your unit to last–probably for even as long as 10-15 years–then follow these steps for RO system maintenance. 

  • If you are going to be away from home for quite some time, shut off the feed water valve, drain the system, and shut off the valve on top of the reservoir tank. 
  • Replace the carbon and sediment filters once annually. 
  • Regularly clean and sanitize the system meticulously. 
  • Watch out for any leaks, as well as components that may have been affected by high pressures. 
  • Replace the membrane every 2 years. 
  • Check the pressure of the reservoir tank. 
  • Clean the brine tank once annually. 


Buying a reverse osmosis water filtration system may lead you to spend up to as high as $300, and you might have to purchase filters now and then, but the bottom line is that it’s a great investment. Once you have installed it, just lift the tap, fill up your cup, and you’re good to go! Now, you can drink water straight from your faucet, and you no longer even have to worry if the water contains any pollutants that may be harmful to you and your family!

Andrea Vaso

When Andrea is not writing, you’re most likely going to find her drinking coffee, reading a novel, or watching medical dramas. She holds an undergraduate degree in biology and as of this moment, she is attending medical school.