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Reverse Osmosis Systems
Reverse osmosis systems for home: tankless under-sink units from Waterdrop, tank-style Pentair FreshPoint systems, a countertop hot-and-cold RO dispenser, and whole house reverse osmosis systems from 300 to 7,000 GPD. Authorized dealer pricing, free shipping, 120-day returns, no sales tax outside Minnesota. Which type do you need? Under-sink vs tankless vs whole house is answered below the products.
Reverse osmosis water filters: how to choose the right system
Reverse osmosis pushes water through a membrane fine enough to reject dissolved solids, which is why it removes what carbon filters and softeners can't: arsenic, fluoride, nitrates, lead, sodium, PFAS, chromium and up to 99% of total dissolved solids. The trade-offs are a slower flow than a plain filter, some water sent to drain as concentrate, and mineral-free water that most people prefer remineralized. The decision comes down to where you want purified water: one tap, or the whole house.
Under-sink, countertop or whole house?
| Under-sink RO | Countertop RO dispenser | Whole house RO | |
|---|---|---|---|
| Serves | One faucet, plus fridge or ice maker line | One spot; no plumbing | Every tap, shower and appliance |
| Output | 400–800 GPD tankless, or 75 GPD with a storage tank | Fills an on-board tank; hot and cold on demand | 300–7,000 GPD into a 165–550 gal storage tank |
| Install | Under the kitchen sink, dedicated faucet, drain line | Plug in, fill the reservoir | Main line, tank, repressurization pump; usually a plumber |
| Best for | Drinking and cooking water in most homes | Renters, offices, RVs, no under-sink space | Well contaminants (arsenic, nitrates, uranium), very high TDS, sodium-restricted households |
| Price | $508–$849 | $714 | $2,744–$12,225 with tank kits |
| Shop | Under sink RO systems | Countertop RO dispensers | Whole house RO systems |
Tankless vs tank-style under-sink RO
Traditional under-sink RO (the Pentair FreshPoint line here) makes about 75 gallons a day into a pressurized tank, so it needs cabinet room for the tank but costs less and has no electronics. Tankless RO (the Waterdrop G3 line) uses a booster pump to make 400–800 gallons a day on demand: no tank, faster fill, better pure-to-drain ratio, and a smart faucet that shows TDS and filter life, at a higher price and with a power outlet required.
| System | Type | Output | Pure : drain | Notable | Price |
|---|---|---|---|---|---|
| Waterdrop G3P800 | Tankless | 800 GPD | 3:1 | UVC-LED sterilizer on the outlet; 8-stage; smart faucet | $849 |
| Waterdrop G3P600 | Tankless | 600 GPD | 2:1 | NSF/ANSI 58 and 372; the model most households should start with | $539 |
| Waterdrop G3 | Tankless | 400 GPD | 1:1 | NSF/ANSI 58 and 372; lowest-cost tankless | $579 |
| Pentair FreshPoint GRO-575B | Tank | 75 GPD | Standard | 5-stage; Diamond Flow membrane; no power needed | $699 |
| Pentair FreshPoint GRO-475B | Tank | 75 GPD | Standard | 4-stage; lowest price on this page | $508 |
| Pentair FreshPoint GRO-475M | Tank | 75 GPD | Standard | 4-stage with filter-change monitor faucet | $551 |
Waterdrop cartridges are stocked under Waterdrop replacement filters. Pentair FreshPoint cartridges are in Pentair.
Reverse osmosis for well water
RO handles the dissolved well contaminants nothing else does, but the membrane needs protection: iron, manganese and sediment foul it and hardness scales it. On most wells the order is sediment or iron filter, softener if hardness is over about 10 grains, then RO, with UV if bacteria has ever shown in a test. For drinking water only, an under-sink unit after that pre-treatment is enough; for arsenic, nitrates or uranium at every tap, see whole house RO. Our RO systems for well water collection groups the units and pre-filters that fit together, and a water test tells us which you need.
Remineralization and alkaline RO
RO removes minerals along with contaminants, so the water is low in calcium and magnesium and slightly acidic. Many people prefer the taste of remineralized water, and on a whole house system it protects copper plumbing. Under-sink: add an inline remineralization or alkaline stage after the membrane. Whole house: the remineralizer system after the storage tank.
What a reverse osmosis system costs
| Item | Range | Notes |
|---|---|---|
| Tank-style under-sink RO | $508–$699 | Pentair FreshPoint 4- and 5-stage |
| Tankless under-sink RO | $539–$849 | Waterdrop G3, G3P600, G3P800 |
| Countertop RO dispenser | $714 | Waterdrop A1 hot and cold |
| Whole house RO | $2,744–$12,225 | 300–7,000 GPD, standalone or with tank kit; remineralizer from $605 |
| Annual filters, under-sink | $80–$200 | Pre-filter every 6 months, carbon yearly, membrane every 2 years |
List pricing before any storewide discount. Every system ships free; whole house systems ship by freight and we coordinate delivery.
Frequently asked questions
What does reverse osmosis remove? Dissolved solids: arsenic, fluoride, nitrates, lead, sodium, chromium, PFAS, sulfates and most other ions, plus sediment and, with the carbon stages, chlorine and VOCs. It does not by itself disinfect, which is why UV is paired with it on wells.
Is reverse osmosis water good for you? It's among the cleanest drinking water available. It's low in minerals; if you want them back for taste, add a remineralization stage. Nobody relies on tap water for mineral intake, but the flat taste is real and easily fixed.
Reverse osmosis vs water softener? Different jobs. A softener removes hardness for the whole house so fixtures and appliances don't scale. RO removes dissolved contaminants for drinking water. Many homes run both, softener first.
How much water does RO waste? Tank-style units send roughly 3–4 gallons to drain per gallon purified; the Waterdrop tankless units run 1:1 to 3:1 pure-to-drain, so far less. Whole house systems run 33–50% recovery.
Tank or tankless? Tankless if you want fast fill, less drain water and a small cabinet footprint, and have an outlet under the sink. Tank if you want the lowest price and no electronics.
Not sure which fits your water? Call 800-374-2143 or send us your water test. For arsenic, fluoride, nitrate and PFAS specifically, see our arsenic, fluoride, nitrate and PFAS filter pages.
