Plumbing Picks is reader-supported. As an Amazon Associate, we earn from qualifying purchases at no extra cost to you.
Quick answer from a licensed plumber: Most houses do not need whole-house reverse osmosis; an under-sink system covers drinking water with far less waste. If you need RO at every tap, the Crystal Quest 500 GPD system with a 220-gallon tank and pump is the pick: the maker sizes it for 1 to 4 bathrooms. It needs clean feed water, sends 1 to 2 gallons to the drain per gallon made, and the manual asks for a licensed electrician.
Our pick if you truly need whole-house RO: the Crystal Quest 500 GPD system with 220-gallon tank and pump. Check the Crystal Quest 500 GPD system on Amazon
A whole-house reverse osmosis system treats every drop of water that enters the house. That is a very different machine from the RO unit under your kitchen sink. An RO membrane makes water slowly, so a whole-house system needs a large storage tank and a pump to bring that water back up to household pressure. It also sends a lot of water to the drain, needs clean water going in, and changes what comes out of your taps. For most houses an under-sink system is the better answer, and we say when below. If you have a reason for RO at every tap, this is the short list of complete systems we could document and find in stock.
Whole House Reverse Osmosis Systems Compared
| System | Rated output | Tank kit | Maker’s home size | Recovery | Feed flow |
|---|---|---|---|---|---|
| Crystal Quest 500 GPD | 500 GPD | 220 gallons | 1 to 4 bathrooms | 33% to 50% | 1.5 to 3 gpm |
| Crystal Quest 300 GPD | 300 GPD | 165 gallons | 1 to 1.5 bathrooms | 33% to 50% | 1 gpm minimum |
Ratings and sizes come from the Crystal Quest product page and manuals; the maker sizes tanks and homes by output range. Both listings show Crystal Quest as the seller and were in stock on Amazon when we checked on September 28, 2026. Crystal Quest sells sizes from 200 to 7,000 GPD. We read every Crystal Quest tank-kit listing we could find on Amazon on the check date, more than 20 of them; apart from these two and a duplicate listing of the 300 GPD kit, they showed shipping in 5 to 7 days or unavailable, so we did not link them.
Crystal Quest Whole House Reverse Osmosis System, 500 GPD with 220-Gallon Tank and Pump
500 GPD rating at 77°F and 550 ppm feed · two 2521 thin-film membranes · 1/2 HP motor · 110/220 V · feed flow 1.5 to 3 gpm · recovery 33% to 50% · 3/4-inch feed, 3/8-inch product and waste connections · about 140 lb · 220-gallon atmospheric tank kit with pump and float switch, per Crystal Quest · 12-month limited warranty
This is the smallest size the maker’s sizing table pairs with its 220-gallon tank, and the size the maker points at for a family house: its sizing table pairs 500 to 2,500 GPD systems with a 220-gallon tank and 1 to 4 bathrooms. It is the Thunder 500 in the maker’s manual, a commercial-style RO with a carbonator motor, two membranes and two 5 x 20 sediment sumps. The Amazon listing is the version with the tank kit, so the order includes the storage tank and repressurizing pump; Crystal Quest’s product page says its tank kits also include float switches, which the whole-house setup cannot work without. Confirm the float switches with the seller.
The design works like this, per the maker: the RO unit fills the tank slowly, a float switch turns it on and off as the level drops and rises, and the pump sends water from the tank to the house when you open a tap. The manual rates production at 500 GPD under test conditions and says higher dissolved solids or colder water lower it. Its feed rules are strict: free chlorine must be removed ahead of it, iron and manganese under 0.05 ppm, hardness under 15 grains per gallon, and it asks for a licensed electrician to do the wiring. Where the documents conflict, we say so: the manual lists a unit of 14 x 20 x 27 inches with two 5 x 20 sediment sumps and a multi-stage centrifugal pump, while the product page lists 18 x 24 x 49 inches, a 5 x 10 sediment cartridge plus a 5 x 10 SMART cartridge, and a choice of brass or stainless rotary pumps. The Amazon title says the system includes a sediment and carbon filter, but the manual still says a separate chlorine removal system must be installed ahead of the unit. Ask Crystal Quest which parts ship and whether the included carbon stage is enough for your chlorine level.
- Sized by the maker for 1 to 4 bathrooms, the wider fit of our two picks
- Tank and pump are in the Amazon listing; Crystal Quest lists float switches in its tank kit
- Full manual with feed limits, start-up steps and troubleshooting
- Maker sells it on Amazon directly, so you deal with Crystal Quest for parts and membranes
- Feed water must be clean: iron and manganese under 0.05 ppm and no chlorine, so most houses need pretreatment first
- At 33% to 50% recovery, every gallon of RO water sends 1 to 2 gallons to the drain (our arithmetic)
- The maker’s warranty is 12 months and asks for an operating log, plus a card signed by the installer
- The manual and the product page disagree on the unit size, the prefilters and the pump type, and neither gives the make of the tank pump or the pressure it delivers at the faucets
Verdict: The pick for a family house that really needs RO at every tap, once the water has been tested and pretreatment has been planned.
Crystal Quest Whole House Reverse Osmosis System, 300 GPD with 165-Gallon Tank and Pump
300 GPD rating at 77°F and 550 ppm feed · one 2521 thin-film membrane · 1 gpm minimum feed · recovery 33% to 50% · 3/8-inch feed and product, 1/4-inch waste connections · about 70 lb · 165-gallon atmospheric tank kit with pump and float switch, per Crystal Quest · 12-month limited warranty
The 300 GPD is the Thunder 300 in the maker’s 200 to 400 manual, the smaller of our two picks. Crystal Quest also lists a 200 GPD tank kit, which was not in stock when we checked. Its sizing table calls 200 to 300 GPD the range for 1 to 1.5 bathrooms and pairs it with a 165-gallon tank, 31 inches across and 56 inches tall. It is a smaller unit with one membrane, so it makes water at a rate of about 0.2 gallons per minute (our arithmetic), and the tank does the work of covering a shower or a washing machine.
The same feed limits apply as on the 500: no chlorine, iron and manganese under 0.05 ppm, hardness under 15 grains per gallon. This manual also lists a 10 micron bag filter and a 5 micron stainless steel filter ahead of the membrane and says to change the cartridge at least every month or whenever needed, which is more attention than a cartridge that lasts a year. The maker’s product page lists different prefilter parts for the 300 GPD, so ask which ones ship. It also lists a 2.5 x 14 inch membrane where the manual names a 2521 element.
- Smaller unit and 165-gallon tank than the 500 GPD, for a smaller house
- Maker sizes it for 1 to 1.5 bathrooms
- Tank and pump are in the Amazon listing; Crystal Quest lists float switches in its tank kit
- Only one membrane to replace, per the maker’s parts table
- At 50°F feed water, the manual’s correction factor puts output near 175 GPD, below the 210 gallons a day an average family uses indoors (our arithmetic)
- The manual and the product page disagree on the prefilters, the unit size and the membrane size
- Same clean-feed rules and the same 1 to 2 gallons to drain per gallon made
- Not for a house with a lot of outdoor water use, which the tank and membrane cannot cover
Verdict: The smaller option for a small home with one or one-and-a-half bathrooms (the maker’s sizing), fed with warmer water or used by fewer people than the EPA average, that has already confirmed it wants RO water everywhere.
I send an occasional note when a new guide goes up — repairs worth doing yourself, and the parts that actually last. No spam, no course funnel; written by a licensed Georgia plumber.
Will It Keep Up? Gallons per Day vs. Your House
GPD is a rate over 24 hours, not a flow. Crystal Quest’s manual gives the conversion: gallons per minute equals GPD divided by 1,440. That makes 500 GPD about 0.35 gpm and 300 GPD about 0.21 gpm (our arithmetic). A standard showerhead uses 2.5 gpm, per the EPA, so the membrane cannot supply a shower directly. The tank does that job: a full 220-gallon tank feeds a 2.5 gpm shower for about 88 minutes, and a full 165-gallon tank for about 66 (our arithmetic), while the RO unit refills it between uses.
The daily total is the real test. The EPA says the average American family uses more than 300 gallons a day at home and that roughly 70 percent of that is indoors, which is about 210 gallons (our arithmetic). A 500 GPD rating covers that with room to spare. A 300 GPD rating has little margin, and the manual says production falls with colder water and higher dissolved solids. Its temperature table lists a correction factor of 1.711 at 50°F and says to multiply actual flux by it to get the 77°F figure, so at 50°F a membrane makes about 58 percent of its rating at the same pressure (our arithmetic). That turns 500 GPD into roughly 290, still above 210, and 300 GPD into roughly 175, which is below it.
Outdoor use is the other half. The EPA puts outdoor use at about 30 percent of household use nationally, and much higher in dry regions. Nobody should irrigate a lawn with RO water, so the hose bibs and irrigation line should stay on untreated water, which is a plumbing decision made at the start.
Pretreatment: What Goes in Front of the Membrane
Nothing affects an RO system more than the water going into it, says Crystal Quest’s manual, and failing to meet its feed requirements will foul the membranes and void the warranty. Its list: free chlorine removed, iron and manganese under 0.05 ppm, hardness under 15 grains per gallon, total dissolved solids under 2,000 ppm, pH from 3 to 11, water between 40 and 105°F, and a minimum feed pressure of 35 psi (the product page lists 45 psi in its general specs, so plan for the higher number). It says a chlorine removal system must be installed before the unit, and to ask about water softeners and filtration for the rest. The Amazon titles say “Sediment & Carbon Filter,” but the manual’s pre-filtration section for the 500 describes only sediment sumps, so do not assume the included stages handle your chlorine.
In practice that usually means a sediment stage, a carbon stage for chlorine, and a softener or iron filter if your water needs one, all ahead of the RO. Well owners should start with a lab test rather than a guess: the EPA tells well owners what to test for and to use only certified drinking water labs. See our guides to the best whole house water filter, the best whole house water filter for well water and the best water softener for well water. The manual also says the pump must never run dry and must be fed only filtered water.
What RO Water Does to Your Plumbing
RO takes out most of the dissolved minerals, and the water that is left is more aggressive to metal. An independent extension guide backs the principle. The University of Nebraska–Lincoln Extension lists low pH and low total dissolved solids among the factors that cause corrosion of household copper pipes and fittings, and says naturally soft water is generally more corrosive than hard water because it is more acidic and has low TDS. RO water sits at the far end of that scale (our reasoning: it removes most dissolved solids by design). The same publication describes RO as a treatment that is typically used at one faucet, not the whole house. For whole-house corrosion from low-pH water, the same guide points to a neutralizing filter.
Crystal Quest says the same about its own product. Its manual says the pH of RO water will normally be 1 to 2 points lower than the feed water, and that a low pH can be very aggressive to some plumbing materials such as copper piping. Its product page says pure RO water contains no minerals and can be slightly acidic, and offers a remineralizer as a post treatment to raise the pH and avoid damage to plumbing and fixtures. For the permeate line the manual says to use PVC or another FDA-approved material so the pipe does not dissolve into the water.
In a whole-house setup, the tank pump, copper or galvanized pipe, the water heater and brass fixtures all see the treated water, so this is a decision to make before buying, not after. The EPA lists pH and corrosion tests for homes with corroding pipes. Ask a licensed plumber what your pipe material is and whether a remineralizing or neutralizing stage belongs after the tank.
Where the Water Goes: Reject Water
An RO membrane sends the dissolved solids it removes down a drain line. Crystal Quest gives recovery as 33% to 50%, up to 75% with system projections, and calls it the share of feed water that comes out as product. At 50% recovery, 1 gallon goes to the drain per gallon you use. At 33%, it is about 2 gallons. If a house drinks and washes with 210 gallons a day of RO water (our arithmetic from the EPA figure), that is about 210 gallons a day to the drain at 50% recovery and about 425 at 33%, or roughly 77,000 to 155,000 gallons a year (our arithmetic). The manual says the drain line must run freely with no back pressure, which is one more reason a plumber should lay it out.
When an Under-Sink RO System Is the Better Answer
Most of the water in a house goes to showers, toilets, laundry and yard, where nobody needs dissolved solids removed. The EPA puts showering alone at nearly 40 gallons a day for the average family. Drinking and cooking water is a few gallons of that (our reasoning). An under-sink RO system treats only that water at one tap, needs no large storage tank or repressurizing pump, and sends far less to the drain in total because it only makes the water you drink and cook with. For copper in drinking water, University of Nebraska Extension calls bottled water or a point-of-use unit where water is consumed the most economical approach. Our best under-sink reverse osmosis systems guide covers those. If the goal is hard water, a softener does that job, and if it is chlorine, taste or sediment, a whole-house carbon filter does; see reverse osmosis vs. water softener and under-sink vs. whole-house water filter. Whole-house RO makes sense when a lab test shows a dissolved contaminant you need out of every tap, or the total dissolved solids are high enough to damage fixtures and appliances.
A quick word on cost, without prices: our cost to install a reverse osmosis system guide covers the installed range for both kinds, and the whole-house version is a much larger job.
How to Compare Any Whole-House RO Quote
Most buyers of this kind of system get a quote from a local dealer. Ask each dealer, and check the maker’s documents, for these six things:
- Rated GPD and the test temperature. Crystal Quest rates its systems at 77°F; ask what temperature a quote’s rating assumes, and derate it with that maker’s temperature table for your cold-water temperature.
- Tank size, pump and float switches. Ask whether the repressurizing pump and float switches are included, and how big the tank is against the space you have.
- Recovery rate and the drain. Ask what recovery the system runs at and where the drain line goes, since it must run free with no back pressure.
- Pretreatment: included or required. Crystal Quest’s limits are chlorine removed, iron and manganese under 0.05 ppm, and hardness under 15 grains per gallon; other makers publish their own. Get in writing which of these the quote covers.
- Post-treatment for pH. Ask whether a remineralizer or neutralizing stage is included, and what your pipes are made of.
- Warranty. Length, what starts it (receipt or installation), what paperwork it needs, and whether labor and travel are covered.
Install: Plan on a Licensed Plumber and Electrician
This is not a weekend job. The maker’s documents describe a system with a feed line, a chlorine and sediment stage, a high-pressure pump, a drain line that cannot be restricted, a tank and a repressurizing pump, and float switch wiring. The manual says a licensed electrician should wire it to code, with a protective earth ground, and that the free-standing unit should be bolted down. It asks for an operating log to keep the warranty, and its warranty runs 12 months from receipt or installation, whichever is later (installation must be within three months of shipment), and asks for a validation card signed by the buyer and the authorized installer within 30 days of installation. It does not cover labor or travel.
A 220-gallon tank is about 42 inches across and 44 inches tall, according to the maker, and the 165-gallon is 31 inches across and 56 inches tall, so measure the door and the space first. Add the drain, a permeate line in a compatible material, pretreatment ahead of it and a plan for the piping after it, and you have a job for a licensed plumber and electrician licensed in your state. We do not install these; this page is a buying guide.
What We Left Off
Tankless RO units sold for homes, such as the iSpring CRO1000, are not whole-house systems. iSpring’s manual lists 1,000 GPD as up to 0.7 gpm, tells you to use it on municipal water, and has no tank or repressurizing pump. That is fine for a kitchen or a small business; it cannot cover several taps at once. We also skipped systems sold by resellers that we could not match to a maker manual, and the Crystal Quest listings we found out of stock or shipping in a week on the check date.
FAQ
Can you put a reverse osmosis system on the main water line of a house?
Yes, but not the small under-sink kind. The RO unit makes water slowly into a storage tank, and a pump sends it to the house. Crystal Quest builds these as point-of-entry systems with a 165 to 500 gallon atmospheric tank, a pump and float switches, and its manuals say to have a licensed electrician wire them.
How many gallons per day does a house use?
The EPA says the average American family uses more than 300 gallons a day at home, about 70 percent of it indoors. That puts indoor use near 210 gallons a day (our arithmetic). A shower alone runs 2.5 gpm on a standard showerhead, far more than an RO membrane makes in a minute, which is why the tank matters.
How much water does whole-house reverse osmosis waste?
Crystal Quest’s manuals give recovery as 33% to 50%, and up to 75% with system projections. At 50% recovery, 1 gallon goes to the drain for every gallon of RO water. At 33%, it is about 2 gallons. Those rates come from the maker’s recovery formula; your own rate depends on the feed water and how the drain valve is set.
Will reverse osmosis water hurt my plumbing?
It can. Crystal Quest’s manual says RO water is normally 1 to 2 points lower in pH than the feed water, and that a low pH can be very aggressive to some plumbing materials such as copper piping. The maker offers a remineralizing post filter for that reason. University of Nebraska Extension also lists low pH and low dissolved solids as corrosion factors for copper plumbing. Have the water tested and ask a licensed plumber about your pipe material first.
Do I need a water softener with a whole-house RO system?
Often, yes. The manual sets maximum hardness at 15 grains per gallon and says that for hard water with a scaling risk you should pretreat with an antiscalant or a water softener. It also asks for chlorine removal ahead of the system, and its feed limits for iron and manganese are 0.05 ppm each.
Why Trust Plumbing Picks
Plumbing Picks is written by a licensed Georgia journeyman plumber. Every size, rating, dimension and spec on this page comes from the manufacturer pages and documents listed below, which we opened and read, or from the Amazon listing we link; nothing here comes from hands-on testing. Each linked product was sold by its maker, Crystal Quest, on Amazon and listed in stock when we checked on September 28, 2026. Where a link goes to Amazon we may earn a commission at no extra cost to you. Nobody pays to be included here. More on who writes this and how we pick.
Sources
- Crystal Quest: Whole House Reverse Osmosis System (product page, specifications and tank kit)
- Crystal Quest: Thunder point-of-entry reverse osmosis installation and operation guide, models 500 to 2500
- Crystal Quest: Thunder point-of-entry reverse osmosis installation and operation guide, models 200 to 400
- iSpring: CRO1000 installation instructions and operating manual (for the 0.7 gpm figure)
- US EPA WaterSense: How We Use Water
- US EPA WaterSense: Showerheads
- US EPA: Protect Your Home’s Water (what to test for and certified labs)
- University of Nebraska–Lincoln Extension: Drinking Water: Copper (NebGuide G1360, revised November 2013)
- Amazon listings for the Crystal Quest 500 GPD and 300 GPD whole-house systems with tank kits (linked above)
Bottom Line
Whole-house reverse osmosis is a tank, a pump, a drain and a pretreatment train, not just a filter. Buy one only if a lab test says you need RO at every tap; otherwise put RO under the kitchen sink. If you go ahead, the Crystal Quest 500 GPD with the 220-gallon tank is the size the maker points at for a family house, and the 300 GPD with the 165-gallon tank is the smaller option. Plan the pretreatment, the drain, the pipe material after the tank and the licensed installers before you order.