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If you’re shopping for a water filtration system, you’ll quickly find that reverse osmosis systems are a popular choice. These multiple-stage water filtration systems can remove up to 99 percent of total dissolved solids (TDS) from your water supply, giving you water that tastes fresh and is clean from contaminants.
At the heart of these water filtration systems is a reverse osmosis membrane, which is so fine that virtually nothing but pure water molecules can squeeze through. Most reverse osmosis systems usually include anywhere from 3 to 6 stages of filtration to remove everything from lead and arsenic to hormones and bacteria. One thing you’ll strongly want to consider on your list of must-haves for a reverse osmosis system is a re-mineralization filter, which adds back in beneficial amounts of calcium and magnesium.
Many reverse osmosis systems are designed to be installed under your kitchen sink and include a water dispenser to be mounted on the sink or countertop. There are also countertop reverse osmosis systems that are a good choice for renters or anyone that is averse to drilling into cabinets or counters. You'll want to look for a system that has enough capacity for your whole family (most standard sizes are equipped to handle 3-4 people), and pay attention to the amount of waste produced and the speed of the filter.
So which one is right for you? We've done the research and found the best options on the market, so you can buy the right one for your home's needs.
Best Overall: APEC Water Systems Essence Premium Quality 75 GPD pH+ Alkaline Mineral Under-Sink Reverse Osmosis Drinking Water Filter System
Stage: 6 | Flow Rate: 0.052 GPM | Water Filtration Technology: Alkaline or Calcite, Carbon Block, Coconut Shell Carbon, Sediment | Primary Material: Plastic | Dimensions: 16 x 27 x 19 inches
Filters only need to be replaced annually
Has a re-mineralization filter
Sip on pure, clean water with the addition of the APEC Ultimate 6-Stage Reverse Osmosis Water Filter System for home. This reverse osmosis system is easy to mount under the sink and earns top marks for easy installation and excellent customer service. With super capacity filters, you only need to change the filters once a year to enjoy clean and safe water every day.
The APEC Ultimate 6-Stage Reverse Osmosis system removes up to 99 percent of bacteria, contaminants, and solids, but it also adds back in calcium and magnesium, which are beneficial minerals for your health and improve the taste of drinking water. The system is rated for purifying up to 75 gallons per day, which is plenty for the average family’s daily needs. The system includes a flow restrictor and an automatic shutoff valve that help to reduce wastewater to 3 gallons for every 1 gallon of purified water produced.
Since this is an under sink reverse osmosis system, you’ll need to set aside space for the 4-gallon pressurized tank, which measures 11 inches wide and 15 inches tall. Giving up your cabinet space will seem worth it though when you taste the purified water from the system.
Best Budget: PureDrop 5-Stage Reverse Osmosis Water Filtration System with Pre-Filter Kit
Smaller capacity than competition
Stage: 5 | Flow Rate: 0.03 GPM | Water Filtration Technology: CTO, Carbon Block, Coconut Shell Carbon, GAC, Sand | Primary Material: Plastic | Dimensions: 5 x 14 x 15 inches
For an affordable price, you can enjoy drinking water that tastes better and is clean from contaminants. If you add up how much you’re spending on bottled water to achieve the same result, you’re likely to break even quickly with the affordable PureDrop Reverse Osmosis Water Filtration System.
This system can purify up to 50 gallons of water per day and has 5 stages of filtration to remove up to 99 percent of TDS. For every gallon of purified water produced, there are 3 gallons of wastewater. People find the PureDrop Reverse Osmosis System to be easy to install, thanks to color-coded tubing and connections. While it isn’t the most robust reverse osmosis system on the market (it has a 2.2-gallon capacity), it produces good quality filtered water—and the price tag won’t leave an unpleasant aftertaste!
Best for Under Sink: iSpring RCC7AK 6-Stage Under Sink Reverse Osmosis Water Filter System
Stage: 6 | Flow Rate: 0.5 GPM | Water Filtration Technology: Activated Carbon, Alkaline or Calcite, CTO, GAC, Hollow Fiber Membrane, Sediment | Primary Material: Plastic | Dimensions: 5 x 15 x 18 inches
Includes a faucet for countertop installation
If you’re looking for an under sink reverse osmosis system to improve your home's water quality, the iSpring RCC7AK is a top choice that is WQA Gold Seal certified and moderately priced without sacrificing performance or quality.
Like most under sink reverse osmosis systems, you’ll need to clear enough space for the 3.2-gallon pressurized storage tank and the filter cartridges. But once you do, you’ll find that the rest of the installation is easy according to most reviewers. One user mentions that they move every 3 years but are happy to uninstall and re-install the system in each new residence due to the high performance and easy set-up of the iSprings RCC7AK.
The reverse osmosis membrane used in the RCC7AK is rated for up to 75 gallons per day, which is plenty to meet the needs of most households shopping for an under sink reverse osmosis system. It takes anywhere from 1 to 3 hours to fill the storage tank, and the filtered water to waste water ratio is 1:3. A lead-free brushed nickel metal faucet for countertop installation is included so you can bypass the tap and have fresh, clean water on demand.
Best for Drinking Water: Home Master Artesian Full Contact Reverse Osmosis Water Filtration System with Permeate Pump TMAFC-ERP
Stage: 7 | Flow Rate: 0.05 GPM | Water Filtration Technology: Alkaline or Calcite, Coconut Shell Carbon, GAC, Sand | Primary Material: Plastic | Dimensions: 12 x 16 x 20 inches
Has a re-mineralization filter
Delivers great water pressure
For a purified glass of drinking water in a hurry, the 3.2-gallon Home Master TMAFC-ERP Full Contact Reverse Osmosis Water Filter System is hard to beat. This top quality reverse osmosis system offers full contact purification, re-mineralization, and fast dispenser action.
One of the most frequent compliments of the Home Master Full Contact Reverse Osmosis Water Filter System is that it delivers great water pressure when compared to other reverse osmosis kits. This can be credited to the permeate pump along with the 3/8 inch dispenser tubing used in this system, which results in a faster flow of water than the typical ¼ inch tubing found on many other reverse osmosis systems.
Like most reverse osmosis water filtration systems, there will be some audible noise when the system is filtering water—but it shouldn’t be distracting. If it is, something may have gone wrong during installation. Fortunately, most people find the installation to be straightforward and customer support to be stellar if there is a problem.
It isn’t the most affordable system, but it does reduce wastewater compared to many other systems. For every 1 gallon of purified water, there is just 1 gallon of wastewater, thanks in part to the permeate pump. Maintenance is easy for this reverse osmosis system—you’ll only need to change the filter once per year or every 2,000 gallons.
Best for Well Water: iSpring RCC7AK-UV Reverse Osmosis Drinking Water Filtration System with UV Sterilizer
Stage: 7 | Flow Rate: 0.05 GPM | Water Filtration Technology: Activated Carbon, Alkaline or Calcite, CTO, GAC, Hollow Fiber Membrane, Sediment, Ultraviolet Light | Primary Material: Plastic | Dimensions: 8 x 18 x 15 inches
Includes a UV sterilizer
1-year limited warranty
If your home takes advantage of a natural well, you can use a reverse osmosis system to make sure that the water you’re drinking is safe and pure. The 3.2-gallon iSpring RCC7AK-UV is a top choice if you’re shopping for a reverse osmosis system for well water.
This water filtration system has seven stages of treatment, including an 11-watt UV light to zap any microorganisms that may be lurking in well water. While this isn’t usually a major concern for homeowners on municipal water, the conditions of a well sometimes harbor bacteria and microorganisms that could pass through your plumbing and into your glass. A UV sterilizer is an efficient, effective way to eliminate this risk and have more peace of mind when drinking well water.
The reverse osmosis membrane of this system is equipped to process 75 gallons of water per day (with a filtered water to waste water ratio of 1:3). Like other popular iSpring reverse osmosis systems, the RCC7AK-UV can easily be mounted under the sink. For the greatest peace of mind when drinking well water, take advantage of the purification power of reverse osmosis combined with the sterilization of UV light in this water filtration system.
Best for Apartments: RKIN OnliPure Countertop Reverse Osmosis Water Filter
Stage: 4 | Flow Rate: 0.5 GPM | Water Filtration Technology: Carbon Block | Primary Material: Plastic | Dimensions: 14.5 x 9.5 x 16.25 inches
No installation required
Must empty purified water tank to use again
No matter what you call home, you want access to purified water that is free of contaminants. If you’re looking for a reverse osmosis system for apartment use, or in another small space like a condo or RV, then check out the space-saving OnliPure Countertop Reverse Osmosis Water Filter.
The OnliPure has a footprint and appearance similar to a pod coffee maker, but instead of serving up java, this mighty machine delivers purified water. Pour one gallon of tap water into the reservoir and the OnliPure will give you 0.5 gallons of filtered, pH-balanced water in about 15 minutes. Just keep in mind that you’ll need to empty the tank of purified water before you can add water to the fill-up tank for another round of filtration.
People love the quick, easy operation of this machine and the fact that they don’t have to install anything or run hoses to the tap. The convenience of a reverse osmosis system for apartments doesn’t come cheap though. Still, this is one of the sleekest, most portable reverse osmosis systems we’ve seen. Whether you’re a renter or looking for a mobile water filtration system, the OnliPure is a great choice.
Best Countertop: APEC Water Systems Ultimate Counter Top 4-Stage Reverse Osmosis Water Filtration System
Stage: 4 | Flow Rate: 0.0625 GPM | Water Filtration Technology: Coconut Shell Carbon, Sand | Primary Material: Plastic | Dimensions: 6 x 14 x 6.5 inches
Purifies up to 90 gallons a day
No permanent installation
Can only be used with standard faucets
No way to hide tubes
Most reverse osmosis systems require you to do a bit of under-sink installation and drill a hole for a separate dispenser, but you can also opt for a countertop model that saves your cabinet space and won’t require any drilling. The APEC Portable Countertop Reverse Osmosis Water Filter System can be set up quickly and easily with no permanent installation necessary.
This countertop reverse osmosis system sits in close proximity to your sink faucet, and the filters are connected to the tap through several tubes. It’s important to know that this system can only be used with a standard kitchen faucet—designer models, spray heads, or pull-out versions won’t work.
If you’ve made room on your counter for this water purifier, you can at least conceal the filters by purchasing a model that comes with a white snap-on case. But whether you go with a case or not, you will have to live with tubes running to the faucet.
The APEC Countertop Reverse Osmosis System isn’t the most budget-friendly or discreet water filtration system you can find, but it might be the right choice if you can’t install an under-sink water purification system. Surprisingly, the reverse osmosis filter for this compact unit is rated for purifying up to 90 gallons of water per day.
Our best overall pick is the APEC Water Systems Essence Drinking Water Filter System (view at Wayfair), which is easy to install and has super-capacity filters that only need replacing once a year. If you're on a budget, check out the PureDrop 5-Stage Reverse Osmosis Water Filtration System (view at Lowe's). With 5 stages of filtration, it can purify up to 50 gallons of water per day.
What to Look for in a Reverse Osmosis Water Filter
Unlike traditional water filters, not all of the water that is pumped through a reverse osmosis filter comes out the other side as drinkable water. Only a relatively small percentage—50 percent or less—is filtered, and the rest is considered waste. When possible, avoid units with 75 percent or more waste, especially if you are treating a high volume of water per day. This unit is typically measured in ratio form, so a tank that produces 75 percent waste will have a filtered water to waste water ratio of 1:3.
Reverse osmosis filtering takes time, so most filters of this type have tanks that store water, rather than filtering it on demand. If your family drinks a lot of filtered water or you are filtering all of your tap water through reverse osmosis, make sure your tank is big enough to accommodate your needs.
While there are reverse osmosis filters that can filter water as you need it, most of them take some time to refill. If you are replacing your regular tap water with purified water, look for a unit that can filter 50 or more gallons a day (the unit measurement for this number is called GDP). If you're just using it for drinking water, you can opt for a unit with a slower refill rate and a smaller tank.
Why Trust The Spruce?
This article was written by Erica Puisis, a freelance home writer who has been contributing to The Spruce since 2017. When researching picks for this list, she consulted dozens of customer and third-party reviews, considering the container size, filter speed, and water waste of each system.