The 10 Best Reverse Osmosis Systems: Reviews & Ultimate Guide

Buying Guide for a Reverse Osmosis System

Buying a Reverse Osmosis system for your home is not easy, because there are different factors to consider and several different options in the market. We put together all the relevant information to help you understand how to select the best RO system for you.

What to Look For in a Reverse Osmosis System

When researching for a Reverse Osmosis system to buy, there are a few factors that you should consider before making your decision:

Filtering Stages

Just one water filter won’t be able to remove all the different types of contaminants and impurities, so typically Reverse Osmosis systems combine multiple filters, each one representing a different stage in the filtration process.

More stages don’t necessarily mean that a RO system is better, but means that more filtering is done to the water to ensure its purity.

A 4-stage RO system is able to purify your water, but there are larger RO systems with more stages, which may include stages to add minerals lost in previous stages, or additional filtration stages to improve the water taste.

Waste Water

A major drawback of Reverse Osmosis systems is that they generate a lot of waste water in order to produce pure water because not all the water that goes through the system comes out as drinking water.

You will find out in the RO specifications that this feature measured as a ratio, i.e., a system that produces 75% of waste water will be represented as a 1:3 ratio (25%:75%), which means that to produce 1 gallon of filtered water, it produces 3 gallons of wastewater.

RO systems with a waste ratio worse than 1:3 are not a great choice, particularly if you need to filter a considerable amount of water.

The amount of waste water generated is linked to the pressure of the inflow water, higher pressure is better as a smaller amount of water is wasted. Some RO systems have pumps that will increase the pressure and help to reduce the waste water ratio.

One thing that you can do is to reuse the wasted water for other uses, like watering your lawn.

Water Output or Gallons Per Day (GPD)

Another important factor to consider is the amount of filtered water a RO system can generate in one day.

Take into consideration that the metrics mentioned in the RO specifications come from tests taken in standard conditions (water pressure of 60 psi and water temperature of 77 ºF or 25 ºC), which may differ from a real-life situation.

You can use our water use calculator to calculate how much water you need for drinking and cooking, and choose your RO system according to your family’s needs.

If you need more filtered water or if your home water pressure is too low (below 40 psi) a RO system with a booster pump might be a better choice for you.

Water Source

This is an important factor for most of the water filters because depending on where you live, the water that comes to your house might have different contaminants.

If you know which contaminants you need to deal with, then you can check if the RO system is able to remove them.

Some RO systems are better than others to filter the different contaminants that come from well water.

Tank Size

The reverse osmosis process is not fast, so most of the RO systems have a pressurized storage tank to store the filtered water to make sure you always have pure water when you need it, instead of having to wait for it to be filtered at the moment.

Before purchasing a RO system, you should consider your family’s drinking needs to ensure that the tank has the right capacity.

There are also some tankless Reverse Osmosis systems that don’t need a tank and produce pure water faster than usual, so it might be a good idea for you if you don’t have enough room for the storage tank.

Ease of Installation

Before buying a RO system, you should decide where it will go, and if you have enough room for it.

Another important thing is to check the top of your sink as most RO systems will require a separate faucet, which may not be easy to install.

When buying a RO system, you should consider if you will be able to install it by yourself or if you will need some external help. If the second scenario is most likely, then you add that potential cost to your budget.

Remineralization

Reverse Osmosis systems are great at removing contaminants, but in the process, they also remove minerals that are good to us, like calcium and magnesium.

Some RO systems have a re-mineralization filter to add back at the end of the process important minerals that were removed during the initial stage.

This is not essential because if you have a balanced diet, you will get magnesium and calcium from your food.

Replacement Filters

A Reverse Osmosis system has more than one filter, and they need to be replaced from time to time to ensure they are filtering properly.

While this is easier in a system with just one filter type, in a RO system you need to replace different filters, with distinct frequencies.

Usually, the semi-permeable membrane needs to be replaced every 2 years, while the sediment, carbon, and polishing filters should be replaced every year.

Benefits of Owning a Reverse Osmosis System

Having a Reverse Osmosis system is a great option for your house. You can check the main benefits below:

Removes Contaminants & Impurities from Your Water

One of the key benefits of an RO system is that it removes several contaminants, significantly improving the quality of the water that you drink.

A RO system can remove heavy metals, chlorine, bacteria, nitrates, arsenic, impurities, and much more.

Improve Water Taste & Odor

Another important benefit of a RO system is that it improves the taste and odor of your water, because some of the removed contaminants are responsible for the bad taste.

One of the most common reasons for the rotten egg taste of unfiltered water is the presence of hydrogen sulfide [1], which is removed by a Reverse Osmosis water filtration system.

Simple to Install

Typically, installing a Reverse Osmosis system is simple, and is something that you could do by yourself without the need of a plumbing expert.

Easy to Maintain

RO systems need some maintenance, specifically, the different filters need to be changed periodically.

But this is a simple task, as most of the RO systems are designed to be simple and easy to swap filters in a few steps.

Saves you Money

Buying a RO system will save you a lot of money, considering the other option you have to drink clean water, which is purchasing bottled water.

The price of a RO system is just a small fraction compared with the amount you spend to buy bottled water every year.

Environment Friendly by Removing Bottled Water Consumption

Another benefit of using a Reverse Osmosis system instead of bottled water is that it is an environmentally friendly option.

If you drink purified water instead of bottled water you are heavily reducing the amount of plastic waste that goes into our oceans.

What Is a Reverse Osmosis Water Filter System?

Reverse Osmosis is a process in which unfiltered water is pushed through a semi-permeable membrane that blocks contaminants and impurities. You can learn more about Reverse Osmosis in our article about it.

Reverse Osmosis Water Filter System is one of the most popular and effective methods to get high-quality drinkable water, as it is really effective in removing a diversity of impurities and contaminants [2].

How Does a Reverse Osmosis System Work

But a Reverse Osmosis system does not use only a semi-permeable membrane to remove contaminants, there are more components and processes in place.

Read below about the Reverse Osmosis’s different components, and how it works step-by-step.

Reverse Osmosis Components

Pre-Filters

In a RO system, before the water reaches the RO membrane, it passes through a set of filters to ensure that larger impurities are removed to avoid damaging the semi-permeable membrane.

RO Semi-Permeable Membrane

The semi-permeable membrane filters all the particles larger than 0.001 microns, removing up to 99% of water contaminants.

This component is the core of the Reverse Osmosis system, as this ultra-fine filter ensures that almost all the water that passes through it is pure.

Post Filters

Typically, the RO system has a post-filter step, in which the water passes through a carbon filter after leaving the pressurized tank and before reaching the final consumer. Some RO systems have additional filters as part of this post-filter component.

This is to ensure that any weird taste and/or odor is removed from the water before you drink it.

Shut-Off Valve

These are automatic valves that detect when the tank is full and shut off the system.

Flow Restrictor

A flow restrictor creates high pressure into the water and pushes it through the RO membrane, restricting the flow of RO rejected water.

Storage Tank

Usually, RO systems have pressurized storage tanks to store the purified water before being consumed. This is to avoid having to wait for the water to be purified only when you want to drink it.

Remineralization Filters

Not all the RO systems have this, but some will have an additional remineralization filter to add back to the purified water some important minerals, such as calcium, magnesium, or iron, that were removed in earlier steps of the RO process.

Faucet

A RO system usually comes with a faucet that you should install in your sink to get the water filtered by this device.

Pumps

Some RO systems have a booster pump that will increase the pressure inside the RO system, making sure it has good efficiency.

If your water pressure is low, you may want to consider installing a permeate pump to increase your RO system output and decrease the waste water generated, increasing its efficiency.

Some pumps can improve the waste water efficiency from 1:3 to 1:1, which is a huge saving in the long run.

Reverse Osmosis System Filtration Process Step by Step

Most of the Reverse Osmosis systems have 5 steps, but most recently some manufacturers added additional steps to improve even more the quality of purified water.

Let’s check the 7 steps (including the additional ones) of a RO System:

Step #1: Sediment Removal

The first filter, a sediment filter, removes larger particles (5-micron and above) and contaminants like sand, rust, or dirt.

Step #2: Carbon Filter

In this step, the water passes through a carbon filter that removes more harmful chemicals such as chlorine.

This not only purifies the water, but also improves its taste and odor, and most importantly, prevents harmful contaminants from reaching and damaging the RO membrane.

Multiple carbon filter cycles can be used in this step, some RO systems have more than one carbon filter.

Step #3: Reverse Osmosis

In the most important step of the process, the water passes through the semi-permeable RO membrane which has ultra-fine pores that block even the smallest particles, leaving only pure water to go through.

Step #4: Contaminants & Impurities Removal

The suspended contaminants & impurities in the water flow out of the RO system through a specific pipe, avoiding cross contamination.

Step #5: Polishing Carbon Filter

The filtered water passes through a final carbon filter before going directly to your faucet to ensure that bad smells and odors are eliminated from the water before you drink it.

This is the final step for many Reverse Osmosis systems, but some will have additional steps that we will cover now.

Step #6: Remineralization

In this additional step, some important minerals that were removed by the RO membrane are added back to filtered water.

This step will also improve the taste of your water, make it healthier with the addition of beneficial minerals, and make it less acidic.

Step #7: UV Filtering

Also an additional step, some RO systems use UV filters to remove microorganisms, bacteria, and viruses from the water, adding an additional layer of purification.

Contaminants Removed by Reverse Osmosis System

A Reverse Osmosis system is really effective at removing contaminants from your water, being able to remove up to 99% of contaminants and impurities, such as heavy metals, bacteria, pesticides, lead, nitrates, etc.

In the next chart you can find the maximum percentage of each contaminant that a Reverse Osmosis system is able to remove from your water.