Finding the right under-sink reverse osmosis (RO) system can feel overwhelming with so many options promising pure, great-tasting water. These advanced filtration systems are designed to remove a vast array of contaminants, from heavy metals like lead to chemicals like chlorine and fluoride. The result is clean, refreshing water straight from your tap, saving you money and the hassle of buying bottled water.
This roundup simplifies your search by highlighting eight of the best systems available. We have considered factors like filtration stages, certification, water waste ratio, and special features such as alkaline remineralization. Whether your priority is certified purity, easy installation, or adding healthy minerals back into your water, there is an ideal system here for your home.
Our Top Picks for Under-Sink RO Systems
- Home Master TMHP HydroPerfection Reverse Osmosis System
- iSpring RCC7AK, NSF Certified, Alkaline 6-Stage RO System
- APEC Water Systems ROES-50 Reverse Osmosis Water Filter
- Express Water Reverse Osmosis Alkaline Water Filtration System
- iSpring RCC7AK 6-Stage Under Sink RO System
- APEC Water Systems ROES-50 Essence Series RO System
- Express Water RO5DX Reverse Osmosis Filtration System
- Home Master TMAFC-ERP Artesian Full Contact RO System
Home Master TMHP HydroPerfection Reverse Osmosis System
The Home Master HydroPerfection is a high-performance, 9-stage system designed for efficiency and health. It stands out with its patented 2-pass alkaline remineralization process, which adds beneficial minerals back into your water not once, but twice. This results in water that is not only exceptionally pure but also has a superior, balanced taste reminiscent of premium bottled mineral water.
This system is built for speed and conservation, featuring a fast 4.5-second glass fill rate and an impressive 1:1 waste water ratio, meaning it wastes far less water than many standard RO units. For ultimate safety, it includes a UV sterilizer that is EPA registered to eliminate 99.9% of germs and viruses. An iron prefilter makes it a robust choice for homes with well water.
iSpring RCC7AK, NSF Certified, Alkaline 6-Stage RO System
The iSpring RCC7AK is an NSF-certified system that combines thorough filtration with a mineral boost. Its patent-pending alkaline remineralization stage restores healthy minerals like calcium and potassium, resulting in clean water with a balanced, higher pH. This feature is perfect for those seeking the health and taste benefits of alkaline water directly from their tap.
Installation is simplified thanks to a patented top-mounted faucet design, allowing you to secure the faucet entirely from above the counter without struggling underneath the sink. For easy maintenance, the system includes a transparent first-stage housing so you can visually monitor sediment buildup and know exactly when a filter change is needed.
APEC Water Systems ROES-50 Reverse Osmosis Water Filter
APEC’s ROES-50 Essence Series is a WQA certified, top-tier 5-stage system built for reliability and maximum contaminant removal. This system is engineered to remove up to 99% of harmful impurities, including arsenic, chlorine, lead, fluoride, and heavy metals, providing water that is often crisper and better-tasting than bottled water.
With over 20 years of experience, APEC has designed this system for long-term, trouble-free operation. It uses premium, long-lasting filters and is built to be a quiet, dependable workhorse in your home. It is an excellent choice for those who want a no-fuss, highly effective RO system from a trusted leader in water filtration.
Express Water Reverse Osmosis Alkaline Water Filtration System
The Express Water 10-Stage system offers comprehensive filtration combined with alkaline mineral addition. This robust setup is designed to remove up to 99.99% of common contaminants like Lead, Chlorine, Fluoride, and PFAs, ensuring your water is safe and clean.
After the purification process, the alkaline filter stage uses Active Mineral Technology to add essential minerals such as Calcium, Potassium, and Magnesium back into your water. Express Water also focuses on a user-friendly experience, with a design that is straightforward to install and understand, empowering you to manage your home’s water filtration without needing professional help.
iSpring RCC7AK 6-Stage Under Sink RO System
This iSpring model is a dedicated 6-stage under-sink system focused on delivering purified and remineralized drinking water. The core of its design is the multi-stage filtration process that effectively reduces contaminants, followed by a final stage that enhances the water’s quality.
The inclusion of an alkaline remineralization filter is a key benefit, as it improves the taste and pH level of the purified water. This system is built for homeowners looking for a complete solution that not only filters but also enhances their water, providing the quality and taste of premium spring water from a convenient under-sink unit.
APEC Water Systems ROES-50 Essence Series RO System
The APEC ROES-50 from the Essence Series is a certified ultra-safe reverse osmosis system built with a 5-stage filtration process. It is engineered to provide a reliable supply of high-purity drinking water by aggressively removing a wide spectrum of dissolved impurities.
This system is known for its robust construction and use of high-capacity filters, which contributes to its long service life and consistent performance. It’s an ideal choice for those who prioritize proven filtration technology and want a dependable, low-maintenance system from a reputable brand with a long history in the industry.
Express Water RO5DX Reverse Osmosis Filtration System
This Express Water RO5DX model is an NSF certified 5-stage system designed for effective and reliable water purification. The certification provides an extra layer of confidence, verifying that the system meets strict standards for material safety and structural integrity.
As a complete kit that includes a faucet and storage tank, it offers a straightforward solution for setting up a purified water source in your kitchen. The five stages of filtration work to reduce a long list of contaminants, delivering clean, safe drinking water while maintaining a compact and efficient design suitable for most under-sink spaces.
Home Master TMAFC-ERP Artesian Full Contact RO System
The Home Master Artesian Full Contact system incorporates advanced technology to improve efficiency and water quality. A key feature is the integrated permeate pump, which boosts water pressure to the membrane. This results in a higher pure water production rate and a significantly reduced waste water ratio.
This system also includes a remineralization stage, ensuring the purified water is not only clean but also great-tasting and non-corrosive. The combination of the permeate pump and remineralization filter makes this a high-efficiency option for households looking to minimize water waste while enjoying the benefits of mineral-enhanced water.
Buying Guide: How to Pick the Right Under Sink Reverse Osmosis System
Choosing one of the many 8 best reverse osmosis systems under sink can feel overwhelming. I have installed a few of these in my own homes over the years, and I have learned that it is not just about the brand name. You need to think about what will fit your space, your water, and your lifestyle. Getting this right means you will have great-tasting water without any headaches down the line.
First, consider the installation space. Measure the area under your sink carefully, including the height, width, and depth. Do not forget to account for your existing plumbing and garbage disposal. Some systems have a single, compact unit, while others have multiple separate filters and a tank. The tank size is another key factor. A larger tank, like a 3- or 4-gallon one, means you will have more filtered water ready to go for a busy family. If you have a smaller household or limited space, a smaller tank or even a tankless model might be a better fit.
Next, look at the filtration stages. A basic system might have 3 or 4 stages, but many modern ones go up to 6, 7, or even more. The core is the reverse osmosis membrane, but additional stages can include sediment filters, carbon blocks, and post-filters like mineralizers or alkaline filters. A mineralizer, for instance, adds back beneficial minerals like calcium and magnesium, which can improve the water’s taste. If you are concerned about water waste, pay close attention to the drain ratio. More efficient systems can have a 1:1 or 2:1 ratio, meaning for every gallon of pure water produced, only one or two gallons are sent down the drain, compared to older models that could waste 4 or more gallons.
Finally, think about long-term maintenance. Check the cost and availability of the replacement filters. Some systems have proprietary filters that can be more expensive, while others use more standard sizes. Look at the recommended change-out schedule for the pre-filters, post-filters, and the RO membrane itself. A system with quick-change filter housings makes this annual chore much easier. Also, see what kind of monitoring the system offers. A simple indicator light on the faucet or a digital display on the unit can take the guesswork out of knowing when it is time for a filter change.
Frequently Asked Questions
How often do I need to replace the filters?
This depends on your water usage and the quality of your incoming water, but generally, the pre-filters (sediment and carbon) should be replaced every 6 to 12 months. The reverse osmosis membrane lasts longer, typically between 2 to 5 years. The post-filter, if you have one, is often changed annually. Always follow the manufacturer’s recommendations for the specific model you choose from a list of the 8 best reverse osmosis systems under sink.
Is the installation difficult?
Many under-sink RO systems are designed for DIY installation with standard tools and provided instructions. If you are reasonably handy and comfortable with basic plumbing under your sink, you can probably handle it. The process usually involves drilling a hole in your countertop for the new faucet and connecting to your cold water line and drain. If that sounds daunting, hiring a professional plumber is always a good option to ensure it is done correctly.
Why is there a storage tank?
The reverse osmosis process is not instant; it is relatively slow. The storage tank is there to hold the purified water so you have immediate access to it when you turn on the faucet. The tank is pressurized with air, which pushes the water out when you need it. Once the tank is empty, it takes some time to refill. Tankless systems are available that provide water on demand, but they often come with a higher initial cost.
Does reverse osmosis remove healthy minerals?
Yes, the RO process is very effective and will remove virtually all dissolved solids, including minerals like calcium, magnesium, and sodium. Some people prefer this, as it also removes potentially harmful contaminants. However, if you want to retain these minerals for taste or dietary reasons, many modern RO systems include an optional remineralization stage that adds beneficial minerals back into the water after the purification process.
What is the maintenance like?
Beyond replacing the filters on schedule, maintenance is fairly minimal. You should periodically sanitize the system, about once a year, to prevent any bacterial growth inside the tank and housings. It is also a good idea to check for any leaks around the connections from time to time. The storage tank diaphragm may need replacement after several years if it loses its pressure.