How to Install a 5-Stage Reverse Osmosis System

This page may contain affiliate links. If you buy a product or service through such a link we earn a commission at no extra cost to you. Learn more.

Installing a 5-stage reverse osmosis system yourself is easier than you might think. Sure, it might take some time and patience, but armed with plenty of directions and YouTube tutorials, it can be done!

We have put together this handy installation guide for your 5-stage reverse osmosis system, with step-by-step instructions on installing and connecting each component to have you drinking pure water in no time!

Key Takeaways

Here is how to install a 5-stage reverse osmosis system:

  1. Install the faucet by drilling a hole in the countertop or sink. Position it for maximum convenience, ensuring a flat surface is available.
  2. Install the drain saddle on the sink drain line, positioning it above and at a distance from the dishwasher discharge and garbage disposal for optimal placement.
  3. Turn off the water below your sink. Relieve pressure in the water lines by opening the faucet. Detach tubing from the cold water valve and install the shutoff valve. Reconnect the tubing.
  4. For the storage tank, position it within 10 feet of the RO faucet. Apply Teflon tape to the threaded port located at the top. Finally, attach the tank valve/connector by screwing it on.
  5. Install the RO module by mounting and connecting color-coded tubing to the respective fittings.
  6. Install the filter elements.
  7. Open the feed water valve and the RO faucet, ensuring the storage tank valve remains closed. Examine all connections for any potential leaks.
  8. Allow the system to flush any debris.
  9. Close the RO faucet and open the storage tank valve.
  10. Allow the tank to fill, then drain. Repeat 2-3 times.

5-Stage Reverse Osmosis System Installation Instructions

So, how do you install a 5-stage reverse osmosis system?

Well, before we get started, it’s a good idea to note that installation may vary depending on your RO system model and your specific plumbing setup. The instructions given here are general guidelines, so please also check the instruction manual that comes with your particular system.

1. Faucet Installation

If your sink doesn’t already have an extra hole that you want to use (it might be covered by a chrome plate), you’ll need to drill a new hole in either the sink or countertop. Ensure there’s a flat area to place the faucet.

Depending on the material, you may need a special drill bit to prevent scratching or chipping. For a stainless steel sink, mark the spot using a center punch. Gently grind away enough surface material to accommodate the ¼” drill bit, then drill the hole. It’s advised to go extra slow, and a drop of oil can work wonders. If you need a ⅜” or ½” hole, start with a ¼” pilot hole.

Insert the faucet through the hole and secure it from the bottom. Then, attach the water line fitting and tighten it with a wrench.

young girl opening reverse osmosis faucet

2. Drain Saddle Installation

To prevent clogging and to safeguard your RO system from contamination, position the saddle/adapter above and away from the dishwasher discharge and garbage disposal. Also, ensure it is at least 6 inches higher than the p-trap.

Create a ¼” opening in the top or side of the drain line—avoid drilling at the bottom. Affix the drain clamps securely using bolts, aligning the clamp hole with the pipe’s hole. Take care not to overtighten.

3. Feed Valve Installation

  1. Begin by turning off both the cold water supply.
  2. Release the pressure in the water line by opening the respective outlet.
  3. Disconnect the tubing from the cold water valve and install the new feed valve using a wrench to tighten it securely. Don’t forget to close the feed valve at this time.
  4. Connect the cold water tubing to the new valve. If needed, you may require an adapter for this step.
  5. Finally, turn the water supply back on, and you’re good to go!

4. Storage Tank Installation

To maintain proper water pressure, position the water storage tank within a 10-foot distance from the drinking water faucet—fair warning: The filled tank can weigh over 25 pounds, depending on size.

Before installation, wrap several layers of Teflon tape around the threaded port at the top. Attach the tank valve or tank connector, ensuring a secure fit by hand-tightening. In many systems, the storage tank can also be horizontally placed without compromising filtration performance. This is incredibly convenient when space is limited.

5. Mount and Connect the RO Module with Tubing

To connect the module, use the handy color-coded tubing with quick-connect fittings. Ensure the tubes are pushed in as far as possible, and test the connection by gently attempting to pull it back.

To install the water lines for your RO system, follow these steps:

  1. Attach the supply line to the feed water valve, ensuring it is secure. Connect the other end to the feed port of the RO module. Adjust the line length if needed to avoid kinks.
  2. Connect one line to both the tank valve and the outlet port of the filter system.
  3. Connect the next line to the drain saddle and the flow restrictor of the RO module. Cut the line so that water can flow without creating any loops.
  4. Connect the last line to the quick connect fitting of the RO faucet and the post-filter outlet port.

6. Filter and Membrane Installation

To install the various pre-filters, post-filters, and the RO membrane into their respective housings:

  1. For the sediment and carbon pre-filters, unscrew the filter housings, insert the filters, and securely screw the housings back on, ensuring all O-rings are in place. Use the filter wrench to tighten carefully.
  2. To install the RO membrane, remove the housing cap and gently push the cylinder into the socket until it is fully seated. Then, place the cap back on, ensuring a snug fit for any O-rings.
  3. Install the carbon and remineralization post-filters by unscrewing the filter housings, sliding the filters in, and then screwing the housings back on and tightening them with the filter wrench.

7. Start the System

  1. Open the feed water valve and the RO faucet, ensuring the storage tank valve remains closed. During this step, you may hear gurgling noises as air exits the system. Inspect all connections for potential leaks.
  2. After approximately 15 minutes, water will slowly dribble out of the dispenser. Do not be alarmed if the initial water appears slightly darker, as this is caused by carbon fibers being flushed out. Once the dribble starts, close the faucet and open the storage tank valve for several hours to fill the tank.
  3. Once the tank is full, you will no longer hear water running down the drain. At this point, open the drinking water faucet to flush the entire unit.
  4. Once the water flow reduces to a dribble, it indicates that the storage tank has emptied. Close the faucet and allow the tank to refill.
  5. Perform a second flush by opening the faucet. Some manufacturers recommend flushing a new system 2-3 times before use.
  6. Once you have completed the flushing process, the setup is complete.

under sink reverse osmosis system

5-Stage RO System Components

All these installation instructions may not make sense until you get to know the RO system’s components and their purpose.

System Module

This single plastic component connects the various elements of the RO system. These components include pre and post-filters, an RO faucet, and a storage tank.


The pre-filters of a 5-stage RO system usually consist of a sediment pre-filter, which primarily removes debris, and a carbon filter to eliminate chlorine and other chemicals. These pre-filters safeguard the sensitive reverse osmosis membrane from potential harm and fouling.

RO Membrane

The reverse osmosis membrane is the primary water filtration component. Its principal function is to eliminate many contaminants that may have bypassed the pre-filters. By utilizing a semi-permeable membrane, the RO system works by applying pressure to separate impurities and dissolved solids from the water. The pure water moves through the membrane to the storage tank, while the impurities are left behind to be flushed away with the wastewater.


After leaving the storage tank, the RO-filtered water progresses through the post-filtration stages, in this case, a carbon post-filter and a remineralization filter. These eliminate any unpleasant tastes or odors lingering in the storage tank and add healthy minerals back into the water.

Bladder Tank

The pressurized tank stores the reverse osmosis water, guaranteeing a constant supply of filtered water whenever you need it.


RO systems come with a designated faucet for optimal flow rate and to ensure there is no cross-contamination with your regular tap water.

Drain Saddle and Drain Line

These components direct and carry the wastewater produced during filtration away from the unit for disposal. The wastewater contains all the impurities that reverse osmosis has filtered out of the water.

Feed Water Valve

The valve acts as the link between your kitchen sink’s water supply and the RO system.

ASO Valve

When the storage tank reaches its maximum capacity, the auto shut-off valve halts the water filtration system, only to resume once the water in the tank empties.

Check Valve

The function of this valve is to halt any backward flow of water towards the RO membrane, which may cause damage.

Flow Restrictor

This controls water pressure against the reverse osmosis membrane, ensuring it is at optimal pressure to filter effectively.


Your system will have multiple tubes that connect all the components together.


Your system will have fittings and connectors that are usually color-coded so that they are easy to install.

If you have any questions about 5-stage RO system installation please don’t hesitate to leave a comment below!

About the Author Alexandra Uta

Alex is a content writer with an affinity for research and a methodical attention to detail. Since 2020, she has fully immersed herself into the home water treatment industry only to become an expert herself. Alex has been using water filters and similar products for years which has gained her lots of hands-on experience.
Learn more about .


Information provided on BOS is for educational purposes only. The products and services we review may not be right for your individual circumstances.
We adhere to strict editorial guidelines. Rest assured, the opinions expressed have not been provided, reviewed, or otherwise endorsed by our partners – they are unbiased, independent, and the author’s alone. Our licensed experts fact-check all content for accuracy. It is accurate as of the date posted and to the best of our knowledge.

Leave a Comment:

Stan Giles says March 17, 2024

Can I safely { T ] off from the outlet side to supply an ice maker?

    Gene says May 14, 2024


Add Your Reply