The best reverse osmosis system

Ana Sanchez

Reverse osmosis systems filter municipal water in stages. The earlier stages generally remove the bigger contaminants, while the later stages remove the smaller ones.

Many people don't like the taste of tap water, or they live in regions where its purity is less than optimal. While buying bottled water is an option, it can be expensive -- and the bottles can end up in the landfill.

Reverse osmosis systems offer a green alternative that transforms your tap water into great-tasting, contaminant-free drinking water. These systems are installed beneath your sink and provide a dedicated faucet for water that's been filtered of contaminants missed by municipal filtration.

To learn more about this healthy, cost-effective solution to purify your drinking water, read our buying guide. We've also included our top picks, like this reverse osmosis system by Home Master that both purifies and remineralizes your water.

Considerations when choosing reverse osmosis systems


Reverse osmosis systems are typically installed under your kitchen sink. This space may be limited in some households and these systems are comprised of a tank, filters, and tubing, which take up approximately the amount of space of a gallon jug. For a tight squeeze, select a compact model that can fit against a side wall. 


Much like water filtration pitchers, reverse osmosis systems also require periodic changing of their filters. This long-term maintenance can rack up costs, so take into consideration how many filters a system has (some have more than others) and how frequently they need to be changed.


The volume of water a reverse osmosis system can filter in a day is measured in gallons per day (GPD). Generally, a unit can put out approximately 50 GPD, though some are capable of 100 GPD. Be aware that GPD number listed by manufacturers are approximations.

Water source

Reverse osmosis systems are generally designed for households with septic water sources. If you have well water, some manufacturers offer systems that can filter both well and septic water or offer specific modifications for well-water use. However, most systems cannot accommodate well water. 

Number of filtration stages

Water that passes through a reverse osmosis system goes through a number of stages of filtration. Depending on the model, these can range from three to 10 (five stages is the average). Interestingly, a more expensive model doesn't necessarily equate to more stages, just more efficient or consolidated ones.


Reverse osmosis systems offer targeted filtration, which means they can target different kinds of contaminants using different filters. While some systems only contain one type of filter, others offer a variety. Here's a list of the targeted filters your system may include:

Sediment filters remove dirt, sand, and other large particle sediment.
Carbon filters can remove rust, pesticides, and pipe residue. They can also remove the chemicals chlorine and fluoride, which cause an undesirable metallic taste in water.
UV filters use ultraviolet light to kill microbes like viruses and bacteria that can fester in the water and that other filters can't eliminate.
Remineralization filters add back in beneficial minerals that these comprehensive systems often filter out. These are also called alkaline filters because they raise the pH of the water, which some claim has health benefits. If anything, alkaline water is considered better-tasting.

Reverse osmosis system prices

Reverse osmosis systems range from $150 and $600, depending on the features you want. You can find a good mid-range system between $200 and $400 that offers five to 10 stages of filtration.


Q. What's the deal with the skinny faucet included in reverse osmosis systems?

A. All reverse osmosis systems come with a dedicated faucet that's usually thin and tall in design and dispenses a smaller volume of water than a regular faucet. You can always replace it with a compatible faucet as long as it fits with your plumbing components.

Q. Can a reverse osmosis system stream hot water?

A. Unfortunately, it cannot. Reverse osmosis systems are only connected to cold water and only dispense cold water, as hot water may cause damage to the system.

Reverse osmosis systems we recommend

Best of the best: Home Master HydroPerfection Undersink RO Water Filter System

Our take: A premium, alkaline RO system that removes 98% of contaminants.

What we like: Remineralization filter adds back in calcium and magnesium. UV filter kills pathogens. Easy to install, but if you run into problems, excellent customer service offered.

What we dislike: Many component parts to install but instructions are thorough and clear.

Best bang for your buck: iSpring Undersink High Capacity Undersink Five-Stage RO Drinking Filtration System

Our take: Budget-priced RO system that removes a high percentage of contaminants.

What we like: Less than half the price of our Best of the Best while still being tough on impurities. Water tastes fresh. Easy installation and lifetime tech support offered.

What we dislike: Reports of leaky units. Can reduce water pressure.

Choice 3: APEC Water Systems Top-Tier Five-Stage RO Drinking Water Filtration System

Our take: Decently priced RO system that delivers solid performance.

What we like: Low- to mid-priced system with five filtration stages. Chrome faucet has a sleek, modern design. Removes more than a thousand contaminants.

What we dislike: Filters not as long-lasting as advertised. Doesn't remineralize water.

Ana Sanchez is a writer for BestReviews. BestReviews is a product review company with a singular mission: to help simplify your purchasing decisions and save you time and money. BestReviews never accepts free products from manufacturers and purchases every product it reviews with its own funds.

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