What does a reverse osmosis system cost, all in?

Advertised prices, verified

Working out your real cost

1. Pick the format before comparing prices. Under sink tank systems are the established baseline. Tankless systems trade the storage tank for an electric pump and a higher sticker price in exchange for cabinet space and steadier output. Countertop units avoid plumbing entirely, and whole-house reverse osmosis is a different scale of project that most homes do not need.
2. Compare like with like in the table. Within a format, systems differ in stage count, whether a remineralizing stage is included, and pump options for low-pressure homes. Note those differences as you read the table below, because a cheap system missing the stage you wanted is not cheap once you add it.
3. Price the consumables at their intervals. The prefilters and postfilters change on a short cycle and the membrane on a long one, and the maker publishes both intervals. Multiply each replacement's price by its frequency over a few years of ownership; between two similar systems, the consumable schedule often decides the real winner.
4. Decide who installs it. A handy owner can fit an under sink system with the included fittings in an afternoon: the jobs are a feed adapter, a drain saddle, and a faucet hole if the sink lacks one. Hiring it out adds a plumber's visit to the total, which is worth it if drilling a countertop or sink deck is outside your comfort.

What moves the price between systems

Stage count is the visible differentiator and the least important one past the core three: sediment, carbon, and the membrane do the real work, and added stages are polish, remineralization, or marketing. Pay attention instead to the membrane's rated output, the faucet quality, and whether the fittings are standard sizes you can service from any supplier later.

Tankless designs cost more up front because a pump replaces the pressure tank, and they add a small electrical draw to the running cost. Their case is strongest in small kitchens and homes that dislike the tank's stored-water lag; if the cabinet has room and the pressure is decent, the tank format usually wins the value comparison in the table.

The costs that surprise people

Reverse osmosis sends reject water down the drain as part of how the membrane works, so households on metered water or a septic system should factor that habit in, and low-waste or pumped models exist specifically to improve the ratio. It is a running characteristic, not a defect, but it belongs in the total cost picture.

The membrane is protected by the cheap filters ahead of it: skip a prefilter change and chlorine or sediment shortens the expensive membrane's life. A TDS meter is the honest audit of whether the membrane is still performing, and our TDS meter guide covers reading feed against filtered water to catch decline early.

Common questions

Is reverse osmosis worth it over a carbon filter?

They do different jobs. Carbon fixes taste, odor, and chlorine; reverse osmosis also cuts dissolved contaminants such as lead, arsenic, nitrates, and PFAS. If a test names a dissolved contaminant, reverse osmosis is the tool.

What does a typical under sink reverse osmosis system cost?

The table on this page carries live prices from the vendors we track, and a typical under sink system lands near $1,531 before installation and consumables are added in.

How much do the replacement filters add per year?

Prefilters and postfilters change on short intervals and the membrane rarely, and the maker publishes both. Price your model's set at its schedule; between similar systems the consumables often decide the cheaper one.

Does a reverse osmosis system need electricity?

Tank-style under sink systems run on water pressure alone. Tankless models and pumped low-pressure setups use a small electric pump, which adds an outlet requirement and a minor running cost.

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