How to Pick the Right Countertop Reverse Osmosis Water Filter

How to Pick the Right Countertop Reverse Osmosis Water Filter

Are you looking for a countertop reverse osmosis water filter?

Countertop reverse osmosis (RO) filters are one of the most popular types of home water filtration systems. They’re also some of the easiest to install and maintain, making them an excellent choice for renters who want clean, healthy drinking water but don’t have time to fuss with complicated equipment.

Reverse osmosis is one of the best ways to remove contaminants from your drinking water and make it healthier. It removes up to 99% of all contaminants including heavy metals like lead, mercury, chromium 6 and arsenic. And because RO systems use only pressure instead of electricity they are very reliable and easy to maintain.

Why Use a Countertop RO SystemAlcaPUre RO Countertop filter RKIN

You have several options when it comes to the type of RO system you use. One option is to install a filter under your kitchen sink to treat the water you drink. This is called a point-of-use or POU system. Another option is to install the treatment unit where the pipes come into the building to treat water throughout your house. This is called a point-of-entry or POE system.

If you’re a renter, you can’t install a POU or POE system because tenants aren’t allowed to make changes to the plumbing. Fortunately, there are countertop units that allow you to have the benefits of reverse osmosis filtration without having to make any changes to your plumbing.

Countertop Systems – How They Work

A countertop RO system is the same as a whole house or under-sink unit. The only difference is the countertop unit is designed to sit on your kitchen counter. The water is fed into the system through a faucet that you connect to your kitchen sink.

Main components of a reverse osmosis water countertop system

The water flows through a series of filters that remove contaminants and then goes through the RO membrane. The first filter that a countertop RO system has is a particulate filter. This filter removes suspended solids, particles, and turbidity from the water. This is an important step because solids can plug the reverse osmosis membrane and reduce its effectiveness.

The second stage of treatment is an activated carbon filter. This filter removes chlorine from the tap water to prevent oxidation of the membrane. It also removes solvents and VOCs that can degrade the plastic membrane. Each of these compounds shortens the life of the RO membrane and can reduce its ability to remove contaminants.

The next step in the treatment process is the RO membrane. The membrane is a porous material that allows only clean water to pass through. It blocks contaminants like arsenic and lead from entering your drinking water. The net effect is clean drinking water with 99+% of the impurities removed.

The RO process creates a concentrated brine that consists of the impurities that are removed as well as minerals and other dissolved solids. This brine is a waste that is discharged – usually to the sink. RO systems waste a significant amount of water. Typically, 2 to 4 gallons of water are wasted (as brine) for every gallon of drinking water produced.

Remineralization water system

Often, a countertop RO system also has an alkaline filter, also known as remineralization, before the output faucet. This adds minerals back into the filtered water to improve the taste and to prevent corrosion of pipes and plumbing fixtures. Most of these alkaline filters add calcium and magnesium.

A countertop RO system typically has a lower flow rate than a whole house or under-sink unit. This means it may take longer to fill up your glass or pitcher. However, most people feel that the convenience of having a water filter right on the kitchen counter more than makes up for the slower flow rate.

Read my comprehensive article about reverse osmosis remineralization.

Countertop Filter System Configurations

Countertop reverse osmosis filters come in two design configurations.

  1. Faucet connected units
  2. Standalone units

Express Water – Countertop Reverse Osmosis System

This countertop RO system filters up to 4 gallons of water an hour. Replacement filters can be easily and quickly changed out using the quick-connect fittings. It comes with 4 filters: a sediment filter, granular activated carbon filter, reverse osmosis membrane, and post activated carbon filter.

Check Pricing on Amazon

1. Faucet-connected unitsFaucet connected countertop RO system

Some countertop units must be connected to your kitchen (or bathroom) sink to receive water for treatment. Water is automatically withdrawn under the pressure from your tap water. A second hose discharges the brine waste that RO creates to your sink.

These systems usually have a diverter valve located at the faucet connection that allows you to bypass the RO filter for washing dishes and using water that isn’t treated.

A faucet-connected filter system is “driven” by the water pressure in your plumbing. They require a minimum pressure of 35 psi for the filter to function properly. The ideal pressure is around 65 psi. The maximum pressure for most units is 80 psi. If your pressure is higher, then you’ll need a regulator to reduce the pressure.

One drawback of the faucet-connected RO filter is the amount of time it takes to treat the water. I have a countertop RO filter and it takes about 48 seconds to fill an 8-ounce glass.

It can take several minutes to fill a kettle for making tea or a pot for cooking.

2. Standalone units

The other RO countertop system configuration is the standalone type. This system has a tank that you fill with tap water. An internal pump drives the water through the treatment filters into a pitcher or second tank that stores the treated water.

A standalone water system is not connected to your faucet and can be located anywhere that is convenient. This is a big advantage if you don’t have much space right next to your sink or if you want to keep this space uncluttered.

Bluevua Countertop Reverse Osmosis System

The model RO100ROPOT countertop RO system has a very low 2:1 Pure Water to Drain Water ratio.  Filters have a long service life of 12 to 24 months. It produces 0.26 liters per minute of purified water. A borosilicate glass pitcher allows you to process a batch of water automatically so you have it ready when you want it.

Check Pricing on Amazon

Since a standalone unit treats the water in a batch (i.e., all at once), you can pour yourself a glass of water or make a pot of coffee without having to wait for the water to be treated. Many people find this time savings to be a big advantage and is why they purchase this type of filter.

The amount of time it takes the RO membrane in a countertop system to treat one gallon of tap water varies with each model and manufacturer. Some systems can take as little as 15 minutes, while others may require up to four hours.

Stand-alone countertop RO systems do not have a pressure requirement and work with any water pressure (because you fill it with water and it has an internal pump).

My Reviews of Countertop Reverse Osmosis Filter Systems

I purchased and tested several countertop RO filters. I put these units through a series of tests to measure how well they remove impurities from water, how fast (or slow) they produce clean water, how much water they waste, and a lot of other metrics.

  1. Express Water countertop 4-stage RO filter. I gave this countertop unit a score of 3.5 stars out of 5. Read my review of the Express Water countertop 4-stage RO filter for more information on this filter.
  2. APEC Water (RO-CTOP) countertop reverse osmosis filter. This budget filter earned 3 out of 5 of stars in my review. Read the detailed review here.

Features and Options to Consider for Your RO Filter

When selecting a countertop reverse osmosis water treatment system, there are several features and options you should be aware of.

1. Faucet connection

There are two types of countertop configurations based on how it receives water for treatment.

  1. Faucet connected: System is automatically driven by water pressure from your tap and must have a minimum pressure of 35 psi.
  2. Standalone: Tank filled with tap water by the user; internal pump drives treated water into pitcher or second tank. No pressure requirement.

If you purchase a faucet connected filter, check to be sure you have the correct pressure in your home. You also need to confirm that the connection will work with your faucet. Some units are not compatible with faucets that have detachable sprayers. The faucet connection is also where the diverter valve is located that allows you to bypass the RO filter for washing dishes and using untreated water.

2. Water pressure

Faucet connected RO filters are “powered” by the water pressure in your pipes. They typically require water pressure between 35 and 80 psi. The ideal pressure is around 65 psi, but this varies by manufacturer.

If your home has low water pressure (less than 35 psi), you can install a booster pump to increase the pressure. If your home has high water pressure, you will need a pressure regulator to reduce the pressure to the optimum level.

3. Purified water flow rate

Reverse osmosis filtration is a slow process compared to other filtration technologies. Some models can produce one or two cups of water in about 30 seconds, but others may take up to four hours to treat the same amount of water.

If you’re buying a countertop system just for drinking purposes, then faster flow rates are not as important. You don’t have to wait as long for treated water. However, if you want a system that can produce enough water for cooking a large pot of pasta, then flow rate becomes more important.

4. Maintenance factors

RO membranes need to be replaced every few years, depending on the amount of use and type of membrane installed. Replacement membranes can be found at most online water filter retailers or from the manufacturer’s website. Filter life has a big impact on your overall costs.

Read my comprehensive article about RO filter maintenance.

Cost: Replacement filters are the greatest expense for RO systems over time. Check the cost of replacement filters when you’re shopping for a system. Most RO filters include a pre-filter, carbon filter, post-treatment carbon filter, and the RO membrane.

Frequency: Check the manufacturers recommendations for how often the filters should be replaced. Some have to be replaced every 3 months. Others are designed to last 6 months or a year.

Difficulty: A well-designed countertop RO system is very easy to maintain and does not require any tools. Some of the cheaper units, however, may be more difficult to maintain and replace.

5. Alkaline filter

Remineralization filters, also known as alkaline water filters, add minerals back into the filtered water to improve the taste and prevent corrosion of pipes and plumbing fixtures. Most remineralizers add calcium, magnesium, potassium or sodium bicarbonate (baking soda) after the RO membrane.

If you decide to buy an alkaline water filter, make sure it is compatible with your RO system. Not all filters are.

6. AestheticsBRIO 500 RO System

Some countertop reverse osmosis systems are attractive appliances that add to the decor of your kitchen. Many, however, are utilitarian and look very cheap. Make sure the unit you select meets your style and expectations.

Many stylish countertop systems offer fashion features like:

  • Stainless steel models with LCD display
  • Granite or marble look panels
  • Glass container for holding purified water
  • Attractive outer casing
  • Colors that match your kitchen
  • Large water tank

7. Size of unit

An important consideration, especially for apartments, is the amount of space you have for storage. If you purchase a faucet connected model, it will need to sit on your countertop. Other models are designed for freestanding under-counter installation, although they may require a plumber’s assistance during setup.

Some RO systems have small footprints compared to others, so you should check the dimensions before making a final decision. Also keep in mind that you will likely want enough space around the unit for regular maintenance and filter changes.

Benefits and Disadvantages of Reverse Osmosis

Before purchasing a countertop reverse osmosis treatment system for your home, you should be aware of the Pros and Cons associated with them.

Pros of reverse osmosis

Countertop water filters are a good option if you want to have purified water available for drinking and cooking whenever you need it. They are also very affordable, especially compared to other types of home filtration systems. Check the rating of any system before you make a purchase.

  • Very effective at removing contaminants from drinking water, typically 99+%
  • Removes many contaminants (lead, arsenic, PFAS, mercury, VOCs)
  • Inexpensive to operate – most require no or a small amount of electricity
  • Compact and easy to install
  • Some models are very attractive and come in a variety of colors
  • Quick setup (less than 10 minutes) with no plumbing or drilling
  • If you’re a renter, the non-permanent solution is ideal
  • Quiet operation
  • Eliminates the need for bottled water

Drawbacks of reverse osmosis

Countertop RO units have several limitations and negative attributes.

  • The water produced is acidic, so most manufacturers suggest adding baking soda or a remineralization filter to the system to raise pH levels back up
  • Faucet-connected units may not fit all kitchen
  • Some people don’t enjoy the flavor of RO water
  • Reverse osmosis wastes a lot of water (1:2 to 1:6 ratio)
  • Faucet-connected units have a hose assembly that is unattractive and clutters sink
  • Uses free countertop space

Frequently Asked Questions (FAQs)

Is a reverse osmosis filter worth the expense and effort?

A reverse osmosis filter is a great way to reduce the amount of contaminants in your drinking water. They are affordable, easy to install and use very little electricity. However, they do have some drawbacks, including the fact that the water produced can be acidic and taste strange to some people. On whole, they’re definitely worth having.

Are RO filters safe to use?

Reverse osmosis systems are very safe to use and produce pure water for drinking. They do not emit any chemicals or hazardous materials into your drinking water, so they don’t pose any risk for contamination of the environment around you.

They remove essentially all dissolved solids from your water, including the minerals that are good for you – calcium, magnesium, and carbonate. You can purchase a RO filter with a remineralization system to add these elements back to your water.

Is a reverse osmosis filter green and sustainable?

Reverse osmosis filters waste a significant amount of water. Many units dump 2 to 3 gallons of water for every gallon of drinking water they produce.

However, the RO filters are still better for the environment than bottled water or other types of home filtration systems because they don’t require any plastic bottles in their production process. The most important factor to consider – RO filters produce pure water for drinking to protect the health of you and your family.


There are many considerations when selecting the right countertop RO filter for your home. It is important to consider maintenance, cost, water pressure and flow rate before making a decision. I hope this blog post has helped you understand how reverse osmosis filters work so that you can find the best one for your needs!

Boch Richard

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children. You can also follow him on LinkedIn, Twitter and Facebook.

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