Teflon tape (for threaded connections only — never on push-fit)
About 30 unhurried minutes
The 9 steps
Clear the cabinet. You'll be working under the sink — give yourself room and light.
Shut off the cold water valve under the sink. Open the cold tap to confirm it's dead.
Install the feed adapter on the cold-water line (between valve and faucet hose). Teflon tape on the threads, snug — not gorilla-tight.
Mount the faucet. Most sinks have a spare hole (sprayer/dispenser). Otherwise a 1/2" hole in the sink deck. Secure from below.
Connect the drain saddle to the sink drain pipe above the P-trap. Drill the 1/4" hole, clamp the saddle over it.
Hang the unit. Open-frame systems mount with two screws or sit on the cabinet floor — either is fine if it's stable and serviceable.
Run the tubes: feed (from adapter) → system inlet; product → faucet; drain → saddle. Push-fit: push firmly until you feel it seat, then tug to confirm.
Leak-check: dry every connection with the towel, run the system 10 minutes, then inspect each joint with a dry finger. A weeping push-fit usually just needs to be pushed in further.
What not to do
Don't connect to the hot water line. Ever. Heat destroys RO membranes.
Don't use Teflon tape on push-fit connections — it prevents the collet from gripping.
Don't skip the flush. New carbon sheds black fines; new membranes ship with preservative.
When to actually call a plumber
If your under-sink shutoff valve is frozen/corroded, if there's no spare faucet hole and you're not comfortable drilling the sink, or if your drain setup has no accessible vertical pipe for the saddle — those are the honest "call someone" cases. Everything else here is genuinely DIY.
Frequently asked questions
Do I need to hire a plumber?
Usually not. If you can shut off a valve and tighten a fitting, you have the skills. The honest exceptions: frozen shutoff valves, no faucet hole you're willing to drill, or inaccessible drain pipe.
How long does installation really take?
About 30 minutes unhurried for a standard under-sink setup. Add 15 if it's your first time staring at push-fit connectors wondering if they're really in (they are — push hard).
Can I install it on hot water for faster flow?
No. Hot water destroys RO membranes and voids any sane warranty. Cold water line only.
My push-fit connection is weeping — is it broken?
Almost certainly just not fully seated. Depressurize, press the collet ring in, pull the tube out, re-cut the tube end square if it's chewed, and push it back in firmly.
Do I need to drill my sink?
Only if there's no spare hole. Most sinks have a plugged sprayer or soap-dispenser hole you can use instead.
For general information only. This guide explains how residential RO systems work — it is not a substitute for professional water testing or a licensed plumber. We don't cure disease; we filter water.