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Reverse Osmosis System Cost Calculator
Get the installed price of a reverse osmosis system and the part most estimates leave out — what it costs to run. Filters, membrane life, water sent to the drain, and a real cost per gallon.
Built by SubcontractorHub — the software plumbing contractors use to quote, finance, and run every job.
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Pick the system and the install conditions. The running cost is calculated from your water, not from a generic average.
Under-sink covers the great majority of residential RO jobs.
Drilling a granite or quartz top pushes labor toward the high end.
Used at 0.75 gal per person per day for drinking and cooking.
Typical municipal supply is 150–500 ppm. High TDS shortens membrane life.
Softening ahead of RO adds roughly a year of membrane life.
📋 Important: All calculator results are ballpark estimates
The figures shown are approximate estimates based on typical 2026 dealer-installed pricing and should be used for general planning purposes only. They are not a quote. Actual cost varies with brand, local labor rates, existing plumbing, and water test results. Always confirm with a licensed installer or certified water treatment professional before purchasing equipment.
What a Reverse Osmosis System Actually Costs
Installed price by system type
| System | Equipment | Installed | Running cost |
|---|---|---|---|
| Countertop RO | $250 – $500 | $250 – $500 | $95 – $130/yr |
| Under-sink, 3-stage | $150 – $300 | $300 – $550 | $70 – $100/yr |
| Under-sink, 5-stage | $250 – $450 | $450 – $800 | $105 – $150/yr |
| Tankless / high-flow | $400 – $800 | $700 – $1,100 | $130 – $190/yr |
| Whole-house RO | $3,500 – $12,000 | $6,000 – $15,000 | $600 – $1,200/yr |
Whole-house RO is not a bigger under-sink system. It needs an atmospheric storage tank, a repressurization pump, and serious pre-treatment, which is most of the price gap.
The running cost is the half that gets ignored
Three things cost money every year: pre- and post-filters on a six-to-twelve-month cycle, the membrane on a two-to-four-year cycle, and the feed water the system sends down the drain. On a typical under-sink system that is roughly $105 of filters, $25 of amortised membrane, and $30 of water — about $160 a year before you count the equipment.
Spread over a four-person household drinking three gallons a day, that lands around 6 to 8 cents a gallon. Bottled water at a dollar a gallon is roughly fifteen times more expensive, which is the honest version of the payback argument.
Drain water is a real line item
Reverse osmosis works by pushing water against a membrane and flushing the rejected dissolved solids away. A conventional tank system sends three to four gallons to the drain per gallon produced. The storage tank is the reason: as it fills, its back pressure fights the membrane, efficiency collapses, and the last part of every fill is the most wasteful.
A permeate pump is an $80 part that uses the drain water’s own energy to offset that back pressure, and it typically cuts waste by half or more. Tankless designs avoid the problem entirely and run near 1:1. On a household using three gallons a day, moving from 4:1 to 1.5:1 saves roughly 2,700 gallons a year — not enormous in dollars, but the easiest efficiency win available on an RO system.
Soften first, then RO
On hard water the order of equipment matters more than the brand. Calcium and magnesium scale the membrane surface, and a membrane that should last four years can be finished in eighteen months. Putting an ion exchange softener upstream protects it and adds roughly a year of membrane life.
It also corrects a common mistake — buying RO to fix hard water. RO only treats the one tap it feeds, so scale keeps building in the water heater, the dishwasher, and the shower regardless. Use the water softener sizing calculator for the softener and treat RO as the drinking water stage downstream of it.
What drives the labor number
If the sink already has an RO faucet hole and a drain saddle, the install is an hour or two. If a new hole has to be drilled through granite or quartz, add time, a diamond bit, and the risk premium that goes with cutting a customer’s countertop. A run to a fridge or ice maker adds a line, a tee, and often a trip through a cabinet run or a floor. Difficult access — a finished basement ceiling, a long run to the cold supply — is what turns a $200 install into a $550 one.
Frequently Asked Questions
How much does a reverse osmosis system cost?
A standard under-sink reverse osmosis system costs about $350 to $650 installed in 2026, covering roughly $200 to $350 of equipment and $150 to $300 of labor. A five-stage unit with a remineralization stage runs $500 to $800 installed. Tankless high-flow systems are $700 to $1,100. Whole-house reverse osmosis is a different category entirely at $6,000 to $15,000 installed, because it needs a storage tank, a repressurization pump, and far more pre-treatment. Budget another $70 to $130 a year for filters on a point-of-use system, plus a membrane every two to four years.
Is reverse osmosis worth the cost?
For drinking and cooking water it usually is, because the running cost works out around 3 to 8 cents a gallon against roughly $1 a gallon for bottled water. A household drinking three gallons a day spends about $1,100 a year on bottled water and about $90 a year on an amortised under-sink RO system. Where it stops being worth it is whole-house RO bought to solve hardness. Reverse osmosis is an expensive and inefficient way to soften water, and an ion exchange softener does that job for a fraction of the cost.
How much water does reverse osmosis waste?
A conventional tank-style RO system sends about three to four gallons to the drain for every gallon it makes. Adding a permeate pump typically cuts that to roughly one to two gallons per gallon produced, because the pump stops the back pressure from the storage tank fighting the membrane. Tankless RO designs run close to one to one. On a household using three gallons a day, the difference between a 4:1 system and a 1.5:1 system is roughly 2,700 gallons of water a year.
How often do reverse osmosis filters need replacing?
Sediment and carbon pre-filters go every six to twelve months, and the post-carbon polishing filter goes annually. The RO membrane itself lasts longer, typically two to four years, but its life depends heavily on feed water. High total dissolved solids, chlorine reaching the membrane because a pre-filter was left too long, and untreated hardness all shorten it. Softening ahead of an RO system is the single best thing you can do for membrane life.
Does reverse osmosis remove hardness?
It removes hardness from the water it treats, but that is only the drinking water tap, so it does nothing about scale in the water heater, the dishwasher, or the shower. Using RO as a hardness solution also punishes the membrane, because calcium and magnesium scale the membrane surface and cut its life short. The correct order on hard water is a softener first, then RO downstream of it. The softener protects the membrane and the RO handles dissolved solids, sodium, and taste.
What is the cost per gallon of reverse osmosis water?
Between about 3 and 10 cents a gallon for a point-of-use system, once you include filters, the membrane, the amortised equipment cost, and the feed water sent to the drain. The number moves mostly with how much water the household actually draws through it. A system producing three gallons a day spreads its fixed costs over about 1,100 gallons a year, while a system producing one gallon a day spreads the same costs over 365 and costs roughly three times as much per gallon. Low-volume households are where RO economics are weakest.
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Get a Free DemoAll calculations are ballpark estimates based on typical 2026 installed pricing and should be verified with a written quote from a licensed installer before making any purchasing decisions. All calculations are estimates based on historical information and should be verified by the user. This tool is provided as a free service for planning purposes only and is not a substitute for a professional water analysis, a manufacturer specification, or applicable local plumbing code.