The Short Version

The Long Version

Most reverse osmosis (RO) systems get installed under the kitchen sink, serving as a point of use (POU) system.

The only problem is that once you’ve got delicious water on tap, you quickly become dependent on one outlet, reluctant to get your fill elsewhere!

So to avoid members of your household jostling at the kitchen faucet, you may be considering a whole house reverse osmosis system.

Unlike a POU filter, where water is filtered at the end of the journey, a whole house RO system gets to work the minute water first enters the household. As you’d then expect, every ounce of water goes through the purifying process, so you’ll be showering and washing with it too.

Often a whole house system is installed out of necessity. Houses supplied with municipal water don’t typically experience the level of contaminants that warrants such an investment. In rural areas with unsanitary groundwater and dubious well systems, however, there can be huge health risks.

Other situations may also require a whole house approach. Homes near manufacturing or chemical processing plants could have higher levels of volatile organic compounds (VOCs), as well as any number of toxic substances.

Before you can find the best method of sanitizing your water, you need to know what your RO system is going to be up against. In general, water filtration systems remove many metal ions and aqueous salts but for especially challenging circumstances, an RO system is the most viable solution. Many products claim to remove 99% of over 1,000 contaminants. There are even some pollutants, like nitrates and arsenic, which are practically impossible to eliminate in other purification methods.

If you have your heart set on a whole house system, we’ve collected up the best examples for you. We’ve got a bucketful of brilliant options, gladly letting the rest swirl down the drain!

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Best Overall: iSpring RCS5T

PURIFICATION: 5-stage

OUTPUT: 500 gallons per day; 0.34 gallons per minute

DRAIN RATIO: 1:1

PRICE: $

PROS: Minimal waste water; automatic flushing; small tank options are great for smaller spaces

CONS: Quick-connect fittings might leak; installation can be tricky

Not all houses are built equally, so it’s not always the best idea to kit yourself out with an absolute monster of an RO system that you’ll never truly harness. The iSpring RCS5T is designed for the light-commercial space, therefore it can keep efficiency high while still providing an impressive 500 gallons per day.

Although the iSpring RCS5T system can be used tankless, as a point of use (POU) system similar to a water fountain, you do have options to add pressurized tanks for stronger performance. The smallest tank option holds 0.5-3 gallons, which can be accommodated in most cabinets. However, if you’re so inclined, the iSpring RCS5T will pair up nicely with much larger storage tanks, supplying pure water to the entire household.

The patented Side-Flow™ membrane is dual directional, thus works faster than less innovative products. Such an efficiency design means that you can not only use this RO system with water pressures as low as 25 psi (1.7 bar), but also maintain a 1:1 drain ratio. If you’re wanting to conserve as much water as possible, you’d struggle to find anything to beat the iSpring RCS5T.

A 5-stage purification process removes 99% of impurities, thanks to a polypropylene (PP), granular activated carbon (GAC), carbon block (CB) and post carbon filters. This technology removes metals, salts, pesticides, and even carcinogens, such as the trihalomethanes (THMs) created when chlorine used to treat city water reacts with other chemicals present.

Despite the compact design, this filtration system is powerful and dependable. A truly top-class product that lives up to the claims.

Best for Reliability: Apex MR-C1500

PURIFICATION: 4-stage

OUTPUT: 1,500 gallons per day; 1.04 gallons per minute

DRAIN RATIO: 2:1

PRICE: $$$$

PROS: Attractive, low-impact design; inlet and outlet pressure gauges; quality components built in USA; easy-access concentrate and recycle valves; TFC membranes will remove 99% of lead and mercury

CONS: Expert installation may be required; not a dedicated system

The Apex MR-C1500 looks simple enough, yet there’s a heck of a lot going on under the surface. Although a commercial-grade RO system, designed with apartment buildings and offices in mind, it fits right into the home. There are four stages of water purification at play.

First, a polypropylene (PP) pre-filter removes sediment like rust, dirt and sand. These filters extend the lifespan of the RO membrane, which then tackles a heap of toxic substances, such as phosphates, chlorine, copper and even radium.

Lastly, dual carbon block (CB) cartridges remove chlorine, chloramine, pesticides and carcinogenic contaminants. As with any working RO system, bacteria and viruses are also removed. All in all, you’re left with odourless, delicious water that’s 98.5% pure!

While light-commercial products hover around the 500-600 GPD mark, the Apex MR-C1500 achieves an admirable 1,500 gallons per day. This is helped largely by the rotary vane high-pressure booster pump, ensuring that the system can operate optimally in a household with lower water pressure.

From a maintenance point of view, the Apex MR-C1500 does very well. The inlet and outlet pressure gauges can immediately tell you system status, letting you know when it’s time to replace filter cartridges. At the same time, the high-power pump is protected by an automatic low-pressure shut-off and a manual on/off switch gives you full control of your equipment.

With quality components, practical design and exceptionally low TDS potential, the Apex MR C1500 bags a well-deserved spot on the list.

Best for Purity: WECO AQUA-TITAN 0400DI

PURIFICATION: 5-stage

OUTPUT: 400 gallons per day; 0.28 gallons per minute

DRAIN RATIO: 1:2

PRICE: $$

PROS: Removes up to 98.5% of nitrates, fluorides and salts; compact filter cartridges take up less space and are NSF42-rated; multiple filters achieve very low TDS; automatic shut-off 

CONS: Atmospheric tanks and pumps must be bought separately; minimum pressure of 40 psi

While highly sophisticated RO systems do incredible things, there’s always the risk that any one of a higher number of components can go wrong. As reverse osmosis really isn’t too advanced a process, there’s something to be said for the simple yet elegant approach.

The WECO AQUA-TITAN is designed to work with city water pressure, somewhere between 40 and 100 psi. When supplied water pressurized to 80 psi, the system produces up to 400 gallons of purified water per day. This means that you won’t necessarily require electricity. Even so, you could quickly add a re-pressurizing pump – along with a tank and pH filter – to transform it into a very effective whole house solution that doesn’t break the bank.

Fully assembled and tested in the US, the WECO AQUA-TITAN achieves exceptionally low TDS readings. It does this by utilizing both pre and post-filters, rated for 20,000 gallons. In fact, the ‘DI’ in the model number stands for de-ionizing, the final stage of the process that effectively ‘polishes’ the water to an ultra-pure standard. This removes all traces of metals and nitrates that have somehow managed to squeeze through the 0.0001 micron membrane.

Clearly, water quality means a lot to the people over at WECO. Dual 5-micron activated carbon block (CB) filters eliminate chlorine and pesticides, whilst the pre-filter stops debris from damaging the crucial RO membrane. Meanwhile, the filter cartridge housings are all NSF42-certified, helping to further reduce bad tastes and odours (hydrogen sulphide) from the drinking water.

The AQUA-TITAN creates quite a splash, when it comes to purity, proving that outstanding quality doesn’t have to be complicated.

Best for Customisation: Crystal Quest 1500 GPD

PURIFICATION: 4-stage

OUTPUT: 1,500 gallons per day; 1.04 gallons per minute

DRAIN RATIO: 1:2

PRICE: $$$$$

PROS: Complete system; unmatched power; potential lifespan of 20 years; many upgrade options

CONS: Expensive; very powerful for the average home

If you’re searching for serious power, this RO system is not going to disappoint. A once impressive output of 500 gallons per day seems meagre in comparison to the Crystal Quest’s 1500 GPD. If you choose to upgrade further, you can get an RO system capable of as much as 7000 GPD, with storage as large as 550 gallons.

As a dedicated system, an atmospheric water tank and booster pump are included, increasing the flow rate for optimal distribution across an entire house, even during peak usage times. When the tank is full, float switches can cut-off the RO system, increasing product longevity while simultaneously minimizing water waste.

Long-term performance is the name of the game here, with every unit being tested in-house. Boasting easy-access components, simple maintenance and low operational costs, the Crystal Quest aims to perform for as long as 20 years, providing you regularly replace the sediment filter and carbon block.

If you’re looking for a premium option, this whole house RO system is extensively customizable. Firstly, you can add a re-mineralizer and a UV Water Sterilizer. However, dive a little deeper and you can end up with a superior stainless-steel rotary vane pump, concentrate and recycle valves, blending valves for precise TDS requirements, and even a chemical pump outlet.

The Crystal Quest 1500 GPD is not the most powerful model in their range, but it’s certainly the king of capacity for whole house systems.

Best for Versatility: Express Water 600 GPD

PURIFICATION: 5-stage

OUTPUT: 600 gallons per day; 0.42 gallons per minute

DRAIN RATIO: 2:1

PRICE: $$

PROS: Up to 99% of contaminants removed; comes with pressure pump; max inflow pressure of 300 psi; strong stainless steel frame

CONS: Water tank not included; a little loud

With the Express Water 600 GPD, the star of the show is the 5-stage filtration technology. A 5-micron sediment filter catches larger particles. Afterwards, dual activated carbon block (ACB) filters and post-activated carbon (PAC) work either side of the NSF-certified membrane, resulting in a crazy-low TDS.

As a result of extraordinary design, up to 99.9% of impurities like cyanide, radium asbestos and heavy metals are removed, leaving you some of the safest and tastiest drinking water you can get. With a drain ratio of 3:1, you’ll get plenty of it, too! If water conservation is a big factor for you, the Express Water 600 GPD is amongst the best for efficiency.

Not only does the unit remove over 1,000 different contaminants, quality components are both cost-effective and low maintenance. Superior membrane layers, with density grading, perform longer and actually stop a greater number of impurities. The pressure gauges let you know when to change filters and/or membrane, while a pre-installed computer interface module gives you further control.

Considering that the manufacturer includes a preinstalled booster pump and 19ft of tubing, it seems strange that they don’t offer a water tank. Nonetheless, it’s all compatible with a non-pressurized tank, so you’re quickly able to create a powerful, versatile whole house RO system.

The workhorse that you can lead to water, this system will happily run non-stop in a ton of home set-ups.

Best for Mineralizing: WECO HydroSense-0500GAC-CAL-UV

PURIFICATION: 4-stage

OUTPUT: 500 gallons per day; 0.34 gallons per minute

DRAIN RATIO: 1:1

PRICE: $$$

PROS: Laboratory-grade quality; mineralized water for superior taste; UV treatment removes waterborne pathogens; easy installation

CONS: Atmospheric tank and booster pump must be purchased separately

WECO HydroSense-0500GAC-CAL-UV is a bit of a mouthful, but there's a method to the madness. The GAC stands for granular activated carbon, a filter for removing chlorine and pharmaceuticals. CAL is for calcite, a post-filter that alkalizes the water to improve taste and reduce pipe corrosion. UV refers to UV light, which is used to instantly kill bacteria and viruses that have made it through the five 100-GPD RO membranes.

All of these filters play their part in this remarkable RO system, which eliminates up to 98.5% of contaminants like sodium, nitrate, fluoride, lead and mercury. The carbon blocks will absorb herbicides and insecticides, amongst countless other industrial chemicals that end up in groundwater. After all the cleansing, the pH balance filter re-mineralizes the water for superior taste and health benefits.

The pre-filters are either a convenient 10” or a more robust 20” in length, so you can choose how best to run your system. Changing filters can be done easily, using an included tool. In fact, you’ll only need a few extra tools to set the entire thing up, which arrives at your home pre-assembled.

The biggest snag is that you’ll need to purchase a water tank and booster pump separately, though it shouldn’t be too much of an issue. RO systems are fairly standardized, meaning you can find a huge range of compatible products.

Literally designed for laboratories, this system demonstrates that pure water is an exact science, and they’ve clearly done their homework.

BUYING ADVICE FOR WHOLE HOUSE REVERSE OSMOSIS SYSTEMS

Necessary Equipment

To set up a whole house reverse osmosis system, you will need a variety of equipment in addition to the main RO system itself.

STORAGE TANK: Unless you buy a dedicated system, you will need to source an atmospheric water tank.

BOOSTER PUMP: Atmospheric storage tanks are non-pressurised, so you also need a booster pump to re-pressurise the water for effective distribution.

PRE/POST FILTERS: As most RO systems are designed to work with a maximum of 2,000 TDS, those in highly contaminated areas may also need to think about pre and post-treatment. If you run, say, well water straight through your RO system, you risk seriously reducing product lifespan.

Capacity

DETERMINE YOUR REQUIREMENTS: It’s easy to become wrapped up in figures, thinking that 1,500 gallons per day output is fundamentally better than 500. However, the capacity required depends solely on the water usage of the household. It’s estimated that daily water consumption per person is between 80-100 gallons a day. After a little adding up, you’ll be able to tell how much output you require.  

ALLOW FOR YOUR UPPER LIMIT: If output is too low, the RO system will be constantly working to replenish what is being used. If, for some reason, water usage rises significantly – a dinner party, relatives coming to stay – water will be depleted quite rapidly. Large households need to carefully consider their water tank size, as this ensures adequate pressure in times of high usage.

“LAB” vs “REAL” CONDITIONS: It’s also important to note that a 600 GPD rating is based on very precise testing conditions, where temperature and pressure were carefully controlled. In real settings, the system may not achieve as high a rating, meaning you should err on the side of caution.

Waste Water

RO systems are installed at the water’s point of access to your home, therefore all water is purified. While this may sound like exactly what you’re looking for, bear in mind that RO systems waste excess water in order to purify the remainder.

In a whole house system, you shower, flush toilets and wash clothes with treated water, which could lead to significant water waste if your drain ratio is sub-optimal.

WATER DRAIN RATIO: The drain ratio is an important figure, letting you know how much water is purified against wasted (i.e. pure:waste). Many RO Systems operate at a 1:3 ratio, meaning that three gallons of water is wasted in producing a gallon of pure water. With larger, commercial units, a much more favourable drain ratio is achieved because of the higher volumes of water. It’s not uncommon for a whole house RO system to have a drain ratio of 2:1, or even 4:1.

RECOVERY RATE: You may also see efficiency measured as recovery rate. A recovery rate of 50%, for example, means that the system rejects half of the water, translated as a 1:1 drain ratio.

RECYCLE VALVES & PRE-TREATMENT: If you have low efficiency, there’s no telling how many gallons of water you are wasting every day. This can lead to great expense, ruining the enjoyment of your RO system. A recycle valve will allow you to attain a better drain ratio, as may pre-treating the water.

Purification Stages

Purification stages refers to the number of filters involved in the RO systems, as well as how they are layered. Initial purification stages work to eliminate contaminants, while later filters focus on killing off the most stubborn impurities, as well as ‘polishing’ the water.

PRE-FILTERS: RO systems vary in the number of stages used to purify the water. While the reverse osmosis membrane defines the process, there are a number of pre-filters that can be employed to protect the precious membrane layers.

·   A polypropylene (PP) filter, or sediment filter, mechanically removes larger particles, such as sand, dirt and rust.

·   The carbon block (CB) filter is made from a solid block of compressed carbon. They are incredibly effective at filtering a multitude of smaller contaminants.

·   A composite filter (CF) is typically a combination of PP cotton layers with an activated carbon section. These filters achieve the same results as their constituents, yet are presented as a single filter.

·   A granular activated carbon (GAC) filter is made from organic materials high in carbon, such as coconut shell or charcoal. These pre-filters are especially useful for dechlorinating water, but they remove many other chemicals that affect odour and taste, such as hydrogen sulphide.

REVERSE OSMOSIS MEMBRANE: This is the star of the show in your RO system, the core technology behind the entire purification process. It is a semipermeable layer, which just means a solvent (water) will fit through, whilst solutes (contaminants) cannot. A reverse osmosis membrane has a pore size of 0.0001 microns, which is why so many contaminants can be effectively removed. In order to increase the lifespan of this membrane, it’s important to regularly change the pre-filters.

 Additional Treatment

While an RO system does its best to purify your water, you must consider additional steps when dealing with particularly difficult water, such as that with higher “total dissolved solids” (TDS), e.g. over 2,000mg/l.

TOTAL DISSOLVED SOLIDS: Total dissolved solids (TDS) is the term used to describe the inorganic salts and small amounts of organic matter present in solution in water. Generally, a TDS of 300mg/litre is considered excellent, while anything over 900mg/l is considered poor and eventually unacceptable. Most RO systems can easily reduce TDS in water to values of under 50mg/l.

When your water source is high in TDS, it can put additional strain on an RO membrane. For this reason, you should look closely at the pre-filters that a system uses.

PRE-TREATMENT: If your feed water is entering the house in very poor condition, you will likely require some form of pre-treatment. Neglecting this step will damage your RO system, drastically shortening lifespan. As an added bonus, operating costs and maintenance can be made easier when pre-treatment systems are installed.

In the case of hard water, which will really hurt your RO unit, some water softener or anti-scalant mechanism should be considered. If you aren’t yet sure of the quality of your water, have it tested. Practically every RO manufacturer recommends pre-treatment for water over 2,000 TDS.

POST-TREATMENT: As an RO filter removes everything, including minerals, you will often find post-filters, which reintroduce minerals into the water. This doesn’t just enhance the flavour of the water, but also reduces corrosion in pipes and fixtures. Alkalization is necessary because the RO process makes water slightly acidic. You may also come across UV light filtration, designed to attack bacteria and viruses.

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