Reverse Osmosis System Install: DIY Guide
Under-sink RO systems are designed as a DIY kit — tubing connects with push-fit fittings, no soldering required.
DIY-Friendly
RO systems are explicitly designed for homeowner installation with push-fit tubing connections. The most technical step is drilling a hole for the faucet, which most kits include a template for.
Skill Level
Beginner
Time Required
1–2 hours
Physical Demands
Kneeling under the sink — low overall
What this costs
| Hiring it out | $300–$4,800 installed |
| Your time | 1–2 hours |
The figure above is an installed cost — material and labour together. We do not publish a material-only DIY figure for this project because our cost data does not separate the two here, and estimating it by assuming a labour share would be a guess rather than a source.
Run your own numbers with the cost calculator — figures last verified July 2026.
- HomeGuide — Reverse Osmosis System Cost (2026) — retrieved 2026-07-13
- Angi — Reverse Osmosis Water Filter Cost (2026) — retrieved 2026-07-13
Step-by-Step
- 1
Shut off the cold water supply under the sink
Test by opening the tap to confirm water is off.
⚠ Old shutoff valves seize or start weeping once turned after years. Check the valve actually closes fully before you cut into anything.
- 2
Install the faucet or drill a hole if needed
Most kitchen sinks have a pre-drilled hole for a soap dispenser or sprayer you can repurpose; otherwise use the included drilling template.
- 3
Install the feed water adapter
This taps into your cold water supply line to feed the RO system.
- 4
Mount the filter housings
Secure them to the cabinet wall in an accessible spot for future filter changes.
- 5
Connect the drain saddle
Clamps onto your sink drain pipe to route the system's wastewater.
- 6
Connect tubing and flush the system
Run the system for the manufacturer's specified flush time before first use to clear carbon fines.
Tools & Materials
Tools
- Drill (if drilling a new faucet hole)You likely own
- Adjustable wrenchYou likely own
- Tubing cutter (usually included in kit)You likely own
Materials
- RO system kit
- Feed water adapter
- Drain saddle
Permits
Permit requirements for this project vary by state and municipality. Select your state above for specific guidance, or check with your local building department before starting work.
When to Call a Pro Instead
- • Your cold water shutoff valve is stuck or leaking — see the faucet/toilet swap guide for that situation first
Safety Warnings
FAQ
How long does an RO system take to install?
A first-time installation with an existing faucet hole is typically two to three hours. Add an hour if you have to drill a new hole through a stainless or composite sink, and more if the cabinet is cramped enough that you are working blind under the basin.
Do I need to drill into my sink?
Not usually. Most kitchen sinks have a pre-drilled hole occupied by a soap dispenser or side sprayer that you can repurpose for the RO faucet. Drilling is only necessary if every hole is in use — and drilling granite or quartz composite is a job worth handing to a fabricator rather than attempting with a standard bit.
How often do RO filters need changing?
Sediment and carbon pre-filters typically run 6–12 months, the RO membrane 2–5 years depending on your feed water hardness. Skipping pre-filter changes is what kills membranes early — the pre-filters exist to protect the expensive part.
Why is my new RO system leaking at the fittings?
Almost always an under-inserted push-fit tube. The tubing must go fully home past the O-ring, and the cut must be square — a tubing cutter, not scissors. Depressurise, pull the tube, re-cut the end square, and push it fully in before re-testing.
Does an RO system waste water?
Yes — traditional RO units send several litres to drain for each litre produced. Ratios vary by unit, and newer permeate-pump or zero-waste designs cut it substantially. Worth checking the stated ratio before buying if you are on metered water.
Can I install a reverse osmosis system myself?
Yes — RO systems are specifically designed as DIY kits with push-fit tubing, no soldering or specialized tools required beyond a drill if you need a new faucet hole.
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