Reverse Osmosis System Installation: 7 Easy Steps!

If you already own a reverse osmosis system or are still on the hunt, a lot of folks are concerned that installation can be a little tricky for a DIY project. The truth is it’s not too bad!

We will walk through a step-by-step process of how to install a tank-based reverse osmosis system under your sink. Included are diagrams, photos, and even a video from start to finish. Hopefully, this will save you time and added costs on professional installation. Let’s dive in!

Reverse Osmosis Installation Process

Here are detailed instructions on how to install a reverse osmosis system. This took us a little over one hour to install under the kitchen sink. Before we get started, you will need the following tools:

• Electric Drill
• Phillips Head Screwdriver
• Box Cutter
• Adjustable Wrench
• 1/4″ Drill Bit For Saddle Valve
• 7/8″ Drill Bit For RO Faucet

Additionally, we created a video tutorial to assist in the process, which is posted below. I highly recommend watching the video to see what all is entailed.

Step 1: Select Installation Location

• Faucet Mounting: The dispenser faucet should be mounted on the rear lip of the sink. If you have an existing sprayer attachment hole it may be mounted there as well. If you do not have an existing hole, drilling a faucet mount hole will be required. In either case, the faucet should be positioned over a sink.
• Reverse Osmosis System: The RO system assembly is designed to be mounted on any sturdy vertical surface like a cabinet sidewall, exposed stud, or sheetrock. Position it so there is access to a cold water source and drain line. Make sure there is convenient access for servicing.

Step 2: Faucet Installation

• Drill Faucet Hole: Drill the 7/8″ hole at the rear lip of the sink (Note: Double check the hole size for your specific faucet). If you have a stainless steel sink, center punch your chosen location and use a stepped 7/8″ drill bit. If you have a porcelain enamel sink, start with a pilot hole and use the appropriate whole saw to complete the whole making sure to protect the surrounding material.
• Mount Dispenser Faucet: Add the base plate to the bottom of the faucet assembly and place the faucet assembly on top of the hole. Then secure the bottom of the faucet under the sink with the washers and hex nut provided.
• Water Tubing Connection: Fasten the 3/8″ faucet adapter to the bottom of the dispenser and connect the product water tubing to the adapter fitting at the base of the faucet.

Step 3: Water Supply Adapter Valve

• Cold Water Line: Turn off the cold water line at the supply valve and disconnect the hose from the valve. Connect the provided adapter valve to the supply valve. Then reconnect the hose to the adapter valve.
• Insert Tubing: Insert the 1/4″ tubing into the adapter valve fitting so it is snug. Open the cold water valve and check for leaks.

Step 4: Drainage System

• Drain Saddle: Install the drain saddle valve on the drain pipe below the sink and fasten the bolts being careful not to over-tighten.
• Drain Line Hole: Drill a 1/4″ hole through one side of the pipe through the 1/4″ drain line connector fitting. CAUTION: Do not drill through both sides of the pipe!
• Insert Drain Line: Attach the 1/4″ tube through the black compression nut on the saddle valve and hand tighten the nut until it is snug.

Step 5: Mount The Filter Manifold Housing

• Connect Water Lines: Now we are ready to connect the drain line, cold water line, and product line to the RO system assembly. The cold water line and product line will connect to the inlet and outlet of the cartridge manifold, respectively. The drainage line will connect to the RO membrane cartridge.
• Mount RO Assembly: To mount the assembly, there will be a paper template to tape onto the mounting location. Use this template to screw in the mounting screws according to the mounting pattern on the template. Remove the paper and you can now hang the RO assembly on the mounting location.

Step 6: Storage Tank Setup

• Tank Valve: Use Teflon tape to wrap the threads on the top of the water storage tank and connect the tank ball valve on top of the water storage tank.
• Water Line Connection: Connect the water 1/4″ water line to the tank ball valve.
• Tank Sanitization: Inject 3 ml of unscented household bleach through the water line and into the tank. Then connect the other end of the 1/4″ tank line to the filter manifold.

Step 7: System Startup

• System Check: Now that the system setup is completed, turn on the water valves to see if there are any leaks.
• System Flushing: Allow the system to run and fill the tank for 1-2 hours until tank is full. Open the faucet and allow the tank to drain completely so the carbon material and sanitization solution are flushed. Do not drink this water.
• RO Membrane Break-In: Allow the tank to fill completely again. Open the faucet and run the system for 24 hours to break in the RO membrane once the tank is full. Do not use this water once again.
• Ready For Use: Allow the tank to fill one last time and the system is now ready to use.

Reverse Osmosis System Installation Cost

If you don’t want to take the time to install a RO system on your own, you can hire a professional plumber to do the job for you. Installing a reverse osmosis system under your sink is a simple task for a professional and it should not take more than two hours or cost more than $250 ^[1].

This of course depends on the hourly rate, but the additional cost to install should not be significant relative to the overall cost to purchase the system.

Frequently Asked Questions

Where do I install my reverse osmosis system?

The point-of-use (POU) reverse osmosis system is an under-sink unit. They need to be installed in an area that has sufficient space for all the RO assembly components and can be conveniently serviced. Accordingly, you should measure the space to ensure it is adequate before installing your system.

Note that this is different than a whole-house reverse osmosis system that is installed at the point-of-entry (POE) and filters all the water coming into your home.

How long does the startup process take after installation?

Depending on your home’s water pressure, startup flushing can take anywhere from 8 to 24 hours. It’s best to start the process in the morning so the system can flush throughout the rest of the day.

What’s the cost to install a reverse osmosis system?

If you are installing the RO unit on your own, most systems come with everything you need. The only incremental costs will be for tools to install the system if you do not have them already.

If you want to hire a professional to install your RO unit, you can expect it to take no longer than 2 hours and cost under $250.

What if I don’t have enough space under my sink?

If you are tight on space under your sink, but still want the benefits of a RO unit, you can always consider a tankless reverse osmosis system or a countertop RO unit. Both of these options will take less space and the countertop option requires no installation.