Whole house reverse osmosis systems purify every tap in the home, not just the kitchen sink: 300 to 7,000 gallons per day, with storage tank and repressurization pump kits, remineralizers and replacement membranes. Built and tested in the USA by Crystal Quest, sold with free freight shipping, 120-day returns and no sales tax outside Minnesota. How a whole house RO works, how to size one and what it costs to run are below the products.

Whole house reverse osmosis systems: what they do and who needs one

A standard under-sink RO makes a few gallons a day for drinking. A whole house reverse osmosis system makes hundreds or thousands of gallons a day and feeds every fixture, so showers, laundry, ice makers and the water heater all run on purified water. It is the only residential treatment that removes dissolved contaminants across the board: arsenic, fluoride, nitrates, sodium, PFAS, lithium, uranium and high total dissolved solids, the things softeners and carbon filters can't touch.

Most homes don't need one. A whole house RO earns its cost when a well test shows a dissolved contaminant above the health limit, when TDS is high enough to taste or scale everything, when a sodium-restricted household is on softened water, or when a home is on brackish or reclaimed supply. If your problem is hardness, iron or bacteria, a softener, iron filter or UV system is the right tool at a fraction of the price, and those often sit ahead of an RO anyway.

How a whole house RO system works

Because RO production is slow and steady, a whole house system is three parts working together, and the kit options on the product pages reflect that:

The RO unit: sediment pre-filtration and membranes on a frame. It rejects dissolved solids and sends 50–67% of the feed to drain as concentrate (33–50% recovery).
An atmospheric storage tank (165, 220 or 550 gallons) that buffers production so you can run a shower and a washing machine at once.
A repressurization pump and float switches that deliver tank water to the house at normal pressure and cycle the RO unit as the tank draws down.

Choose Standalone if you already own a tank and pump, or Add Storage Tank Kit for the complete package. A remineralizer after the tank is recommended for whole-house use: RO water is slightly acidic and mineral-free, which tastes flat and is aggressive to copper plumbing over years.

Which size do I need?

Size by gallons per day of purified water your household uses, plus headroom for laundry and irrigation. A family of four uses roughly 250–400 gallons a day at all fixtures. Your well or supply also has to meet the unit's minimum feed flow.

System size	Typical home	Storage tank in kit	Where to buy
200 GPD (off-grid)	Cabin, RV, tiny home, drinking and cooking supply	Portable, no tank	Off-grid portable RO
300–400 GPD	1–1.5 bathrooms, 1–2 people	165 gal	Whole house RO
500–2,500 GPD	1–4 bathrooms; most single-family homes	220 gal	Whole house RO
4,000–7,000 GPD	5+ bathrooms, estates, multi-family, irrigation	550 gal	Whole house RO or commercial RO

Whole house reverse osmosis for well water

Well water is where whole house RO is most often the right answer, because wells are where arsenic, nitrates, uranium, fluoride and high TDS show up. Two rules make or break the install. First, pre-treat: RO membranes are rated for feed water up to about 15 grains of hardness with no iron, manganese or sediment, so on most wells the treatment train is iron filter and/or softener, then RO, then remineralizer, with UV after the tank if bacteria is a concern. Second, check pump capacity: the RO unit's minimum feed flow (1.5 GPM for 500–1,800 GPD, 4 GPM for 2,500, 6–10 GPM for 4,000–7,000) has to be available while the house is also drawing. Send us a water test and we'll size the whole train.

What a whole house RO system costs

Item	Typical range	Notes
RO unit, standalone	$2,700–$8,500	300 GPD to 7,000 GPD
Storage tank kit (tank, pump, floats)	+$1,400–$2,500	165, 220 or 550 gallon
Remineralizer	from $605	Sized to system (Big Blue for 300–2,500 GPD; 1.5 cu ft for 4,000–5,000); recommended
Pre-treatment (softener / iron filter)	$800–$2,500	Only if your water needs it; protects the membranes
Annual upkeep	$100–$300	Sediment cartridges every 6 months; membranes every 2–3 years

Prices above are current list pricing for the systems on this page, before any storewide discount; installation by a plumber is extra and varies by site. Everything here ships free by freight and we coordinate delivery with you.

Replacement membranes and cartridges

Every system on this page uses standard-size components, so parts are stocked here rather than proprietary: 2.5″ × 21″, 2.5″ × 40″ and 4″ × 40″ freshwater membranes, plus pleated sediment and SMART pre-filter cartridges. Each product page lists the exact cartridges and membranes by system size.

Frequently asked questions

Is a whole house reverse osmosis system worth it? If a lab test shows a dissolved contaminant you can't remove any other way, or TDS high enough that you're buying bottled water and replacing fixtures, yes. If the complaint is hardness, staining or smell, a softener or iron filter solves it for less and wastes no water.

How much water does it waste? These systems run 33–50% recovery, so one to two gallons go to drain per gallon purified. Concentrate can be routed to irrigation or a dry well where code allows.

Do I need a softener with a whole house RO? On hard water, yes. Scale is the main thing that shortens membrane life, and a softener ahead of the RO is cheaper than replacing membranes early.

Will RO water hurt my plumbing? Untreated RO water is mildly acidic and can be aggressive to copper over time. A remineralizer after the tank corrects pH and puts calcium and magnesium back; it's the reason every kit page recommends one.

Can I add RO to an existing softener and UV? Yes. The RO goes after the softener and before the tank; UV goes after the tank. The schematics on each product page show these complete trains.

Need more than a home can use? See commercial water filtration. Want drinking water only? See under-sink and countertop reverse osmosis. Or call 800-374-2143 and we'll size it from your water test.

500 - 2500 GPD Single Akalizer / Remineralizer

500 - 2500 GPD Single Akalizer / Remineralizer Reviews