It takes about 2-3 hours to install most under-sink RO units with most of that time spent drilling holes for the faucet and the drain line.
Because they know most buyers prefer DIY installation, manufacturers have made their systems very straightforward to set up.
Most RO units come with color-coded parts, quick-connect fittings, and pre-assembled parts.
Below is a detailed guide on how to install a reverse osmosis system under your sink. Countertop systems don’t require any installation, so we are not going to cover those.
As with any other machine, always read the user manual before you do anything.
Check that all the parts are present. If anything is missing or appears faulty or broken, contact customer support.
Familiarize yourself with all the parts and gather all the tools you’ll need.
Where to Install a Reverse Osmosis System
The ideal location is under the sink. It’s the easiest place to connect water from the cold water line and direct the wastewater through the drainpipe.
But that’s not the only space you can install an RO unit. If your under-sink area is too small, you can also set it up in the basement or garage and direct the purified water to the faucet on the sink.
But you might need to install a booster pump to ensure water reaches the faucet with adequate pressure.
Do not install the RO system in a place where freezing conditions are possible and do not install it outside where it will be exposed to the elements.
What You’ll Need
Step-by-Step Installation Guide
Assemble the Filters
This is not necessary if your filters come pre-assembled.
If not, first make sure all filters are present and learn which types of filters the system uses.
Following the user manual, insert the filter cartridges into their housings and then attach them to the filter mount.
Make sure you insert the right cartridges into the right housings.
Some systems like Home Master have the cartridges and housing as one unit. If that’s the case with your system, you need to attach each filter to the mounting.
Check that the filters are in the right order.
With the filters assembled, it will be easy to mount them on the wall under the sink when its time.
Install the Faucet and Drain Saddle
Before you begin the installation, turn off the cold water line and drain it by turning on the faucet until it runs empty.
We’ll start with the most time-consuming steps so that all you are left with is making the final connections.
Installing the Faucet
Installing the Drain Saddle
Before you put the drill away, you’ll need to make a ¼” hole for the drain line.
Select a position away from the garbage disposal and dishwasher discharge to avoid contamination and clogging up the drain.
It should also be at least 6 inches above the P-trap.
Drill the hole on top or side, not at the bottom. Secure the drain saddle around the pipe, being careful not to overtighten.
Making the Connections
The remaining part is easy and quick. You need to connect the right tubes in the right places.
The tubes are color-coded to make it easier to know where they go. Reference your manual for what different colors mean.
Most RO systems use quick connect push fittings, which are easy to work with and don’t require any tools.
Make sure tube connections are secure. Push the tube into the fitting until it doesn’t go any further. Tug slightly at the tube to make sure it is secure.
Double check that everything is connected properly then turn on the cold water.
Look for leaks around connections.
Next comes one of the most important step: flushing the system. Don’t forget it.
The initial RO water is not ready for drinking. Let the tank fill and then empty it 2-3 times (check the manual for the specific number).
After that, the water is ready for drinking.