Top 6 Best Under Sink Reverse Osmosis Systems🥇(April 2024)

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Charlie W. Palmer

Water Systems Expert & Founder at Water Systems Guide

Hi! I'm Charlie. If you're wondering why I started WaterSystemsGuide, it's because I previously worked as a water systems specialist/consultant for a large government initiative in California, USA. However, after leaving, I wanted to provide advice and information for others, to pass my knowledge on, so I created this site!

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Last Updated: 18 April 2024

In this article, we’re going to be talking about the best under sink reverse osmosis water systems that are available on the market.

Reverse osmosis systems are used to remove poisonous substances, contaminants, bacteria, and much more from our water supply, so that the drinking water is clean and able to be consumed in a safe way.

If you’re worried about the quality of drinking water in your home or commercial environment, experts are also giving even more reasons to be concerned.

Why? Well, between 1982 and 2015, millions of Americans got their drinking water from a source that was in violation of the Safe Drinking Act.

And even now, researchers at the nonprofit Environmental Working Group and Northeastern University found out last year that at least 43 US states have sites where toxic fluorinated compounds known as PFAs contaminate drinking water.

That they make your tap water safe to drink isn’t the only reason why you might want to invest in a high-quality tanked or tankless RO system.

These water filters also improve the taste of your water, eliminate up to 99% of all contaminants, neutralize any odors, and improve its quality.

Best Under Sink RO Systems Review – Top 6

• iSpring CU-A4 – 4 Stage – Under Sink RO System – $ – Skip to section
• Brondell Circle – 4-Stage – Under Sink RO System – $$ – Skip to section
• Waterdrop – 4 Stage – Under Sink RO System – 400GPD – $$ – Skip to section
• Waterdrop – 4 Stage – Under Sink RO System – 600GPD – $$$ – Skip to section
• Frizzlife – 3 Stage – Under Sink RO System – 600GPD – $$$ – Skip to section
• Waterdrop – 7 Stage – Under Sink RO System – 400GPD – $$$$ – Skip to section

iSpring CU-A4 – 4 Stage – Under Sink RO System – $

Technical Specs

• Filter Stages: 4-Stage
• Gallons per day (GPD): N/A
• Gallons per minute: N/A
• Water pressure: 40 psi

General Specs

• Price: $
• Dimensions: 10.5 x 4.5 x 12.5 inches
• Weight: 5 pounds

Features

The CU-A4 by iSpring is a very affordable 4-stage under sink reverse osmosis water system and is an excellent choice for most general water filtration applications.

The 4-stage design of this RO machine features a combination of Activated Carbon, Ultra Filtration and KDF filters, virtually eliminates a wide variety of unhealthy contaminants, including bacteria, algae, fungi, giardia, lead, arsenic, iron, nickel, chromium, cadmium, calcium, aluminum, mercury, chlorine, and chlorine treatment by-products, pesticides, hydrogen sulfide, and other organic compounds.

The CU-A4 is flexible, quiet, and durable. It has no moving parts and is very easy to maintain – only requiring occasional filter replacement. spring’s high-capacity, high-performance filters last up to twice as long as other filters and provide maximum water flow – a difference you’ll notice when you turn on the faucet.

The push-to-connect fittings and color-coded tubing simplify the installation process and minimize the possibility of leaks. A well-organized instruction manual guides you step-by-step through the entire installation and testing process. If you do run into an issue, or get stuck, they have a technical support team on hand, Monday thru Friday.

The system is backed by a 1-year manufacturer and spring’s unique lifetime technical support provided right here in the USA.

Pros

• Affordably priced
• 4-stage filter system
• Quiet and effective
• Easy installation

Cons

• Not a whole house system

Brondell Circle – 4-Stage – Under Sink RO System – $$

Technical Specs

• Filter Stages: 4-Stage
• Gallons per day (GPD): N/A
• Gallons per minute: N/A
• Water pressure: 40-120 psi

General Specs

• Price: $$
• Dimensions: 10.5 x 4.5 x 12.5 inches
• Weight: 5 pounds

Features

The Brondell Circle unit is another extremely affordable 4-stage under sink RO water system and is another great choice for most general water filtration applications.

According to Brondell Circle, their system utilizes patented new technology, making the unit up to 10 times more efficient than current conventional reverse osmosis water filters.

It’s apparently very easy to install, including everything you need to get the job done. The refill rate is more than twice as fast as non-electric systems, and equally as fast as those with electric pumps.

The Brondell Circle Reverse Osmosis Water Filtration Systemic Gold Seal-certified by the Water Quality Association for trusted performance and is certified for NSF/ANSI standards 42, 53, 58, and 372.

The system is backed by a 1-year manufacturer warranty.

Pros

• Affordably priced
• 4-stage filter system
• Effective & quiet operation
• Easy to install

Cons

• Not a whole house system

Waterdrop – 4 Stage – Under Sink RO System – 400GPD – $$

Technical Specs

• Filter Stages: 4-Stage
• Gallons per day (GPD): 400
• Gallons per minute: 0.27
• Water pressure: N/A

General Specs

• Price: $$
• Dimensions: 17.32 x 5.91 x 13.9 inches
• Weight: 26 pounds

Features

The G2 under-sink RO system is 5.9 inches wide and takes up very little space under the sink. The faster and more stable water flow will produce a cup of filtered water in 12 seconds.

The RO system uses the filter composition technology with a filtration accuracy of 0.0001 μm, removing most of the contaminants, including heavy metals, and chemical residues in tap water.

The new filter composition technology employs an excellent filter combination to achieve a more efficient filtration. The filters can soften water and effectively remove more than 1,000 contaminants.

The CF filter adopts a sediment PP membrane layer and an activated carbon block layer. It removes common impurities such as sediment, rust, large particles, colloids, residual chlorine, fluoride, and scale.

With its large filtration area, the MRO filter effectively removes over 1,000 impurities such as heavy metals, organic material, and TDS. The activated carbon block improves the taste of the output water.

The system is backed by a 1-year manufacturer warranty.

Pros

• Fantastic customer reviews
• High GPD capacity
• Removes contaminants larger than 0.0001 μm
• Effective & quiet operation
• Easy to install

Cons

• Not a whole house system

Waterdrop – 4 Stage – Under Sink RO System – 600GPD – $$$

Technical Specs

• Filter Stages: 4-Stage
• Gallons per day (GPD): 600
• Gallons per minute: 0.42
• Water pressure: N/A

General Specs

• Price: $$$
• Dimensions: 17.32 x 5.91 x 13.9 inches
• Weight: 26 pounds

Features

The G2 P600 under-sink RO system is similar to the previously mentioned unit, but differs in its GDP rate being 600, as opposed to 400..

It’s 5.9 inches wide and takes up very little space under the sink. The faster and more stable water flow will produce a cup of filtered water in 12 seconds.

The RO system uses the filter composition technology with a filtration accuracy of 0.0001 μm, removing most of the contaminants, including heavy metals, and chemical residues in tap water.

The new filter composition technology employs an excellent filter combination to achieve a more efficient filtration. The filters can soften water and effectively remove more than 1,000 contaminants.

The CF filter adopts a sediment PP membrane layer and an activated carbon block layer. It removes common impurities such as sediment, rust, large particles, colloids, residual chlorine, fluoride, and scale.

With its large filtration area, the MRO filter effectively removes over 1,000 impurities such as heavy metals, organic material, and TDS. The activated carbon block improves the taste of the output water.

The system is backed by a 1-year manufacturer warranty.

Pros

• Fantastic customer reviews
• High GPD capacity
• Removes contaminants larger than 0.0001 μm
• Effective & quiet operation
• Easy to install

Cons

• Not a whole house system

Frizzlife – 3 Stage – Under Sink RO System – 600GPD – $$$

Technical Specs

• Filter Stages: 3-Stage
• Gallons per day (GPD): 600
• Gallons per minute: 0.42
• Water pressure: N/A

General Specs

• Price: $$$
• Dimensions: 15.5 x 5.3 x 14.7 inches
• Weight: 24.4 pounds

Features

This Frizzlife 3-Stage RO water filtration system is a 600 GPD, high flow rate, tankless unit, suitable for under sink installation.

It uses a 2-in-1 composite sediment filter and high-grade reverse osmosis membrane with 0.0001-micron filtration accuracy, providing a 3-stage deep filtration. Remove 99.99% of 1000+ harmful contaminants from tap water, including Lead, Chlorine, Flouride, Heavy metals, Chloramine, VOCs, TDS, Limescale, Arsenic and Asbestos, and more.

This under-counter RO system ensures immediate access to filtered water from dedicated brushed nickel faucet.

The RO water filtration system adopts an internal pump and is able to produce 600 gallons of pure water per day, sufficiently serving the daily water needs of a large family or small company.

The water flow is fast and stable, filling a 330ml cup of water in about 8 seconds.

Pros

• High GPD capacity
• Removes contaminants larger than 0.0001 μm
• Easy & straightforward installation

Cons

• Not a whole house system
• Limited/No customer reviews

Waterdrop – 7 Stage – Under Sink RO System – 400GPD – $$$$

Technical Specs

• Filter Stages: 7-Stage
• Gallons per day (GPD): 400
• Gallons per minute: 0.27
• Water pressure: N/A

General Specs

• Price: $$$$
• Dimensions: 18.1 x 5.7 x 17.8 inches
• Weight: 31 pounds

Features

The WG3-W by Waterdrop under-sink RO system is similar to the previously mentioned Waterdrop units, but differs in its GDP rate being 400 and it includes more filtration stages (7 in total).

The system is certified against NSF 58 for TDS reduction. Using reverse osmosis filtration technology with a filtration accuracy of 0. 0001μm, the system can effectively remove most contaminants including fluoride, TDS, limescale, and heavy metals in your tap water. The system is also NSF 372 certified for lead-free material.

The system can be installed in seconds, and the filter can be replaced within one single turn.

It’s 5.7 inches wide and takes up very little space under the sink. The faster and more stable water flow will produce a cup of filtered water in 12 seconds.

The RO system uses the filter composition technology with a filtration accuracy of 0.0001 μm, removing most of the contaminants, including heavy metals, and chemical residues in tap water.

The new filter composition technology employs an excellent filter combination to achieve a more efficient filtration. The filters can soften water and effectively remove more than 1,000 contaminants.

The CF filter adopts a sediment PP membrane layer and an activated carbon block layer. It removes common impurities such as sediment, rust, large particles, colloids, residual chlorine, fluoride, and scale.

With its large filtration area, the MRO filter effectively removes over 1,000 impurities such as heavy metals, organic material, and TDS. The activated carbon block improves the taste of the output water.

The system is backed by a 1-year manufacturer warranty.

Pros

• Fantastic customer reviews
• 7-stage filtration
• High GPD capacity tankless RO system
• Removes contaminants larger than 0.0001 μm
• Effective & quiet operation
• Easy to install

Cons

• Not a whole house system
• More pricey

Conclusion

All-in-all, we realize that everyone will have different needs and requirements from their ideal RO system, and therefore we cannot provide specific recommendations for your needs.

However, we’ve clearly displayed the GPD (Gallons Per Day) and Cost ($$$) of each of the units, making it easier for you to make your decision and purchase the right unit for you.

• iSpring CU-A4 – 4 Stage – Under Sink RO System – $ – Skip to section
• Brondell Circle – 4-Stage – Under Sink RO System – $$ – Skip to section
• Waterdrop – 4 Stage – Under Sink RO System – 400GPD – $$ – Skip to section
• Waterdrop – 4 Stage – Under Sink RO System – 600GPD – $$$ – Skip to section
• Frizzlife – 3 Stage – Under Sink RO System – 600GPD – $$$ – Skip to section
• Waterdrop – 7 Stage – Under Sink RO System – 400GPD – $$$$ – Skip to section

Summary

Reviewer

Charlie W. Palmer

Review Date

Reviewed Item

Under Sink Reverse Osmosis Systems

Author Rating

5

Product Name

Under Sink Reverse Osmosis Systems