Removing a reverse osmosis (RO) system is a straightforward DIY project that takes about 30 to 60 minutes with basic tools. The process involves shutting off the water, draining the system, disconnecting four main connection points, and restoring your plumbing to its original state. You don’t need a plumber for this, just an adjustable wrench, a bucket, some rags, and a few inexpensive caps or plugs.
Tools and Supplies You’ll Need
Gather everything before you start so you’re not crawling out from under the sink mid-project. You’ll need an adjustable wrench, a small bucket or shallow pan that fits under the sink cabinet, old towels or rags, and plumber’s tape. For sealing things up afterward, pick up a push-fit cap or plug sized for 1/4-inch tubing (the standard for undersink RO systems). Some systems also use 3/8-inch tubing, so check yours before buying caps. You may also want a sink hole cover plate if you plan to remove the dedicated RO faucet.
Shut Off the Water Supply
Start by turning off the cold water supply line feeding the RO system. You’ll find a small valve or T-connector on the cold water pipe under your sink, usually with a quarter-turn handle. Turn it to the closed position. If your RO system also feeds a refrigerator or icemaker, shut off that line too.
Next, close the valve on top of the storage tank. This is typically a ball valve with a blue or white handle. Turn it perpendicular to the tank line to shut it off.
Drain the Storage Tank
Open the dedicated RO faucet on your sink and let all the water drain out. Place your bucket underneath if needed. The tank holds several gallons, so this can take a few minutes. Let it run until the flow stops completely and only air comes out, then close the faucet handle.
Even after the faucet stops flowing, there will be residual water trapped in the tubing and filter housings. Keep your rags handy for the next steps because small amounts of water will leak out every time you disconnect a fitting.
Disconnect the RO Faucet
Working from under the sink, locate the small water line that runs up from the RO system to the base of the dedicated faucet. Use your adjustable wrench to loosen the retaining nut connecting the tube to the faucet stem. Have a rag ready to catch any remaining water that drips out.
Once the tube is disconnected, remove the mounting nut and washer that hold the faucet to the sink from below. These are usually hand-tight or require a wrench. Then pull the faucet up and out through the hole in the countertop or sink. If you’re not installing anything else in that hole, a standard sink hole cover plate (available at any hardware store in chrome, brushed nickel, or other finishes) will give you a clean look.
Disconnect the Feed Water Line
The RO system connects to your cold water supply through a T-adapter or saddle valve that taps into the existing pipe. Disconnect the 1/4-inch tubing running from this adapter to the system’s first filter housing. Most RO systems use push-fit (also called quick-connect) fittings. To release these, press the small collet ring toward the fitting body while pulling the tube out.
Once the tubing is free, you have two options for the T-adapter. If it’s a compression-style T-fitting, you can remove it entirely and reconnect the cold water supply line directly using the original compression nut. If it’s a self-piercing saddle valve clamped onto the copper pipe, removing it will leave a small hole. You can replace that short section of pipe, or simply leave the saddle valve in place with its needle valve closed. Leaving it closed and capped is the easier route, and it creates no issues long term.
Remove the Drain Line
The RO membrane produces wastewater that drains through a small tube connected to your sink’s drainpipe. This connection is made with a drain saddle clamp, a two-piece bracket that wraps around the drainpipe with a small hole drilled through it. Unscrew the bolts holding the two halves of the saddle together and pull it off the drainpipe.
This leaves a small hole (usually about 1/4 inch) in your drain pipe. For tubular plastic drain pipes, which most kitchen sinks use, the simplest fix is wrapping a small piece of rubber patch material over the hole and securing it with a hose clamp. For a more permanent solution, you can replace that short section of drainpipe entirely. Tubular plastic drain sections are inexpensive and connect with slip-joint nuts, making this a five-minute swap.
Disconnect and Remove the Tank
With the valve already closed, disconnect the single tube running from the top of the storage tank. This is another push-fit connection on most systems. Once freed, you can lift the tank out. RO tanks are surprisingly heavy when full, but since you already drained it through the faucet, it should be light. If it still feels heavy, open the valve briefly with the tube disconnected and let any remaining water drain into your bucket.
Remove the Filter Assembly
The main filter housing is usually mounted to the inside wall of the sink cabinet with screws or a bracket. Disconnect any remaining tubes from the filter housings by pressing the collet rings on the quick-connect fittings. Then unscrew the mounting bracket from the cabinet wall. Pull the entire assembly out, along with all the loose tubing.
Check inside the cabinet for any remaining clips, cable ties, or adhesive pads that held tubing in place. Peel or unscrew these to leave the cabinet clean.
Cap Off Open Connections
Before turning the water back on, make sure every open connection is sealed. The main one to worry about is the feed water T-adapter on your cold water line. If you left the T-adapter in place, install a push-fit cap on the open port (1/4-inch for most systems). If you removed the T-adapter and reconnected the supply line directly, check that the compression fitting is snug with no drips.
Double-check the drain saddle hole. Then slowly turn the cold water supply back on and watch all connection points for leaks. Keep a rag nearby and tighten as needed.
Flush the Lines After Removal
After any plumbing work, it’s good practice to flush the lines. Open the cold water tap at your kitchen sink and let it run for a couple of minutes to clear out any debris or stale water from the connection points. If the RO system was feeding your refrigerator, run water through the dispenser as well until it flows steadily.
For a more thorough cleaning, you can sanitize the affected pipes with a diluted household bleach solution. Shut off the main water supply, drain the lines, then fill them with a solution of about two tablespoons of unscented bleach per gallon of water. Let it sit for several hours (ideally 12 hours for a full disinfection), then flush everything thoroughly until you no longer smell chlorine. Food-grade hydrogen peroxide works as an alternative if you prefer to avoid bleach. This step is optional for most situations but worth doing if the system was old or if you noticed any odor when disconnecting the lines.