How much does a reverse osmosis system cost?
An under-sink reverse osmosis system often costs $300 - $950 installed. Whole-house reverse osmosis can cost $4,800 - $8,000+ and should be justified by water testing, not by taste concerns alone.
RO is usually a drinking-water solution first. For whole-home water problems, a water test may point to sediment filtration, carbon, softening, iron treatment, UV, acid neutralization, or a combination instead of whole-house RO.
Reverse osmosis cost by setup
Under-sink RO system
$300 - $950 installedHow to tellDrinking water taste, odor, TDS, or contaminant concern at kitchen sink
The fixInstall RO filters, membrane, small storage tank, faucet, drain saddle, and feed line
Refrigerator or ice-maker connection
$100 - $400+ extraHow to tellHomeowner wants RO water at fridge dispenser or ice maker too
The fixRun approved tubing from RO system to appliance and verify pressure/storage capacity
Whole-house RO
$4,800 - $8,000+How to tellSpecific water test results justify treating all water, often on difficult well water
The fixInstall pre-treatment, RO membranes, storage, repressurization, and drain/wastewater handling
Pre-treatment needed
$500 - $5,000+ extraHow to tellHard water, iron, sediment, chlorine/chloramine, or fouling risk would damage membranes
The fixAdd sediment filter, softener, carbon, iron filter, or other pre-treatment before RO
Filter and membrane maintenance
$50 - $300+ per service cycleHow to tellFlow slows, taste changes, or maintenance interval is due
The fixReplace prefilters, postfilter, and membrane as specified by the manufacturer
Before buying RO
- Get a water test and identify the problem you are trying to solve. RO is not the right first answer for every taste, odor, hardness, iron, or sediment issue.
- Decide whether the goal is drinking water at one faucet or whole-home treatment. The costs and maintenance are completely different.
- Ask where reject water will drain and whether your home has enough pressure/storage for the proposed system.
- Ask for annual filter, membrane, and service costs before comparing installed prices.
Unlock the hiring checklist
Use this before you call a water treatment, so you know what to ask and what to avoid.
Call a pro when…
- A water test shows contaminants that a certified RO system can address
- You are on well water and need pre-treatment before RO
- You want a refrigerator/ice-maker connection or whole-house system
- There is no easy drain, outlet, or cabinet space under the sink
- A salesperson recommends whole-house RO without showing test results
Repair or replace?
Maintain or repair an RO system when filters, tank pressure, tubing, faucet, or membrane are the issue and the system is otherwise sized correctly. Replace or redesign when the system was never matched to the water test, wastes too much water for the home, cannot meet flow needs, or has recurring fouling because pre-treatment is missing.
Need a cleaner scope before you call around?
Use the water treatment checklist to compare the same work, questions, cleanup, and warranty before choosing a local company.
Related questions
Is reverse osmosis worth it?
It can be worth it for drinking-water contaminants, taste, or specific test results. It is not automatically worth it for whole-house use unless testing supports that design.
Does RO remove hard water?
RO can remove many dissolved solids at a drinking-water faucet, but it is not the usual whole-home hard-water solution. A softener or conditioner may still be needed to protect plumbing and appliances.
How often do RO filters need replacement?
Many prefilters and postfilters are changed every 6-12 months, while membranes may last longer. Actual timing depends on water quality and usage.
Why is whole-house RO so expensive?
It needs more than a membrane. Whole-house RO may require pre-treatment, storage tanks, pumps, controls, drains, and ongoing maintenance to serve the entire home.