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Written by: Donavan Jones on August 24, 2018

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The Definitive Guide To Reverse Osmosis System Installation – Learn How to Size, Place & Install Your System

under sink Reverse Osmosis System InstallationDid you know that a reverse osmosis system installation is an easy DIY project?


Below you will find a step by step guide that will help you through each step of the installation process.

Have you heard that they are one of the best ways to produce clean water for your home?


Its because reverse osmosis systems are capable of removing up to 99% of the contaminants floating in your water, unlike other water filtering systems you may have heard about.

In this guide, I’ll provide you with all the resources you need for a trouble-free installation.

Table Of Contents:

Reverse Osmosis System Installation 101

It’s time to learn how you can hook up your new reverse osmosis system the correct way. With a little preparation and the necessary tools, you don’t have to hire a professional plumber to install it the right way. FYI, every ro system comes with a detailed instruction manual. 

Before you start, you need to carefully read all of the steps and safety guideliness in your system’s manual. If you have doubts about what to do next, consult the manufacturer.

How To Install An Under The Sink Reverse Osmosis System

Below you will find the steps you need to take to install your under the sink reverse osmosis system. You can do it yourself in less than 2 hours.

The individual steps may vary from product to product and depends on your plumbing setup. Therefore, the following step by step installation is given as a general approach.

Reverse Osmosis System Installation Diagram

under the sink Reverse Osmosis System Installation diagram

Preparations For The Reverse Osmosis System Installation

Before installing your new reverse osmosis system, you need to check if all of the components fit in their desired location. You want to do this because you want to know beforehand if you need to make any adjustments to the drain or other pipes.

Basic Tools For A Reverse Osmosis System Installation

Locate and assemble all the necessary tools and components. Having all the tools and components pre-assembled will save you from a headache. Below you will find the most common tools and equipment you will need to complete the job.

  • RO System Installation Manual
  • RO Module
  • Water Storage Tank
  • RO Faucet
  • Installation kit including color-coded tubing, filter wrench, stop connector, tank valve, faucet connector, drain saddle, membrane
  • 1/4″ Drill Bit
  • Screwdriver
  • Tubing Cutter
  • Utility Knife
  • Adjustable Wrench
  • Towel


RO faucet

RO Faucet Installation

First, get ready to install the RO faucet. The RO faucet is where the pure and great tasting drinking water will come from. Usually, RO faucets will have a connection with a 1/4″ or 3/8″ tubing fitting. Before you get started you need to decide where you want to place the faucet. If your sink already has an extra hole for the mounting, then you can use that. If it doesn’t, you will have to drill a new hole into the sink or countertop. Depending on the type of material you are drilling into, you may need a special type of drill bit.

Before you can get started drilling, you must gently grind away enough of the surface material to accommodate the 1/4″ drill bit. Now be careful, you need to drill the hole. Go slow to start off. If you are drilling into a metal surface then you can try adding a drop of oil in the hole. Oil can work wonders!

When you are done, you need to remove any remaining metal chips. Keep in mind that the metal chips can damage the surface.

Now place the faucet stem inside the hole and secure it with a nut at the bottom of the faucet. Attach the quick-connect fitting to the bottom of the faucet and tighten it with a wrench.

Drain Saddle Installation

Now you want to install the drain saddle or drain adapter to the drain line. You want to place them as far away as possible from the dishwasher discharge and garbage disposal.


This will protect your Reverse Osmosis System from contamination.

Now that you have a location for the drain saddle or drain adapter you want to drill a 1/4″ hole to the top or the side of the drain line. Never the bottom. Next, put the drain saddle in place secure it with bolts. Make sure that you don’t overtighten anything.

Feed Valve Installation

In this step, you need to install the inlet feed valve to the RO system. This valve connects the RO system to the cold water line of your sink.

Before you start, you will need to turn off both the cold and hot water supply. If you cannot turn the valves or they are broken, then you have to shut off the water supply to your house. Now release the pressure in both the cold and hot water lines by opening the kitchen sink faucet. Next, remove the tubing from the cold water valve and install the new feed valve. Turn the feed valve off.

Attach the cold water tubing back to the new feed valve and turn both the cold and hot water supply back on.

RO Tank Installation

Place the storage tank within 10 feet of the drinking water faucet.


If the storage tank is more than 10 feet from the faucet then you risk the chance of losing significant water pressure.

If you are low on space under your sink then keep in mind that the storage tank can be placed on its side without affecting performance.

Wrap about 5 turns of Teflon or plumber’s tape around the threaded port on top before attaching the tank valve or tank connector. The connector should thread on easily and only needs to be hand tight.

RO Module Connection

At this time, you are going to install the RO module using the color-coded tubing. Don’t forget that trimmed water connections will maximize the water flow rate. However; leaving some extra tubing will come in handy if you ever need to move the RO system.

Pro Tip: There may be water in the tube lines if the system was tested by the manufacturer.  Keep a towel handy to wipe up any mess.

  • Orange Feed Water Line – Push the orange supply line onto the feed valve of the existing sink line faucet supply on the end and to the feed port of the RO module on the other. If need be, trim the line if necessary so it won’t get kinked. Tighten the nut a half turn past hand tight.
  • Green Tank Line – Connect the green line to the pressure tank valve and to the outlet port of the filter system
  • Black Drain Line – Connect the black line to the previously installed drain saddle and to the flow restrictor of the RO module. If it is possible, trim the line so the water can flow downhill without any loops.
  • Blue Faucet Supply Line – Connect the blue line to the quick connect fitting of the RO faucet and to the post-filter outlet port.

Keep in mind that many RO modules can be mounted in both the horizontal and verticle position. Please consider that you will need to access the RO module for filter replacements and other maintenance tasks.

Filter And Membrane Installation

Now that all of the connections are made, place the filters and RO membrane into their housings. Review the reverse osmosis system installation manual that is provided. Typically, the first filter is the sediment filter, followed by the carbon filters, and lastly the membrane.

To put the RO membrane in place you must remove the housing cap and carefully push the cylinder into the socket. Then put the housing cap back on.

Starting The Reverse Osmosis System

checklist to start system

It’s finally time to start your new system! Here is how:

  • 1. Turn on the feed water valve, but make sure that the storage tank valve is closed. At this point, you don’t want water going into the tank
  • 2. Check all fittings for leaks.
  • 3. Once a little bit of water is coming out of your faucet you want to cut it off and open the storage tank valve.
  • 4. Filling the tank can take about 6-10 hours. When it is full, you will no longer hear water running down the drain. This is the time when you have to open the RO faucet to flush the unit.
  • 5. When the water is again coming out at a trickle, this means that the storage tank is now empty. Close the faucet and let the tank refill.
  • 6. Once the tank is full, flush the system a second time by turning the faucet back on

Prior to use, it is recommended to flush your new RO system 2-3 times. Once you’ve done that, the installation is completed and your water is ready for drinking.


In conclusion, installing a reverse osmosis system is a straight forward process. Placing your system, running and connecting the water lines, and flushing the system are the basics to reverse osmosis system installation. If you have any question about this guide or you need help installing your reverse osmosis system please contact us.

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Donavan Jones

About Donavan Jones

Donavan Jones is the marketing manager at Florida Water Analysis. He's an expert in inbound marketing and lead generation. In his spare time, Donavan is developing a video game with his friends and family.


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