9 Best Under Sink Reverse Osmosis Systems [In 2025]
Water is essential for life, and having access to clean, safe drinking water is a top priority for many households. While municipal water supplies are treated, they can still contain traces of contaminants, such as chlorine, lead, and other impurities. Enter reverse osmosis (RO) systems, a highly effective water filtration solution designed to remove up to 99% of contaminants, providing you with pure, great-tasting water right from your kitchen sink.
Table of Contents
Our Top 3 Picks
- 【Industrial Leading Remineralization Technology】 Reverse osmosis filtration not only removes harmful substances, but also good elements. VIOMI Master M1 remineralize the filtered water via flushing true ore harvested from deep under earth. Porous Structure is reshaped at 2192 ℉ for simulating lava ion exchange to achieve optimized mineral release. Note that TDS shall be higher than normal RO filtered water due to mineral elements.
- 【1000GPD Flow with Smart Faucet】The Viomi M1 reverse osmosis alkaline water filter with an initial flow rate of up to 100 oz/min (3 L/min), enjoy pure water on demand-no waiting, even at peak usage times. The built-in HD touchscreen displays real-time water quality insights (TDS) and one-touch dispensing, perfectly paired with the M1’s intelligent filtration system.
- 【Reduces TDS & PFAS Microplastics】 Our 9-stage reverse osmosis Filtration effectively reduces total dissolved solids (TDS), PFOA, PFOS, chlorine, chloramine, lead, heavy metals and other harmful substances in water. With a filtration precision of 0.0001 μ𝐦, so you can trust every drop of your drinking water. Enjoy exceptional purity with a TDS reduction of up to 90.57% and PFOS/PFOA reduction of up to 99.44%.(Tested by official third-party laboratory (SGS)).
- 【3:1 Pure-to-Drain Ratio, Save More & Green More】 Most tankless RO water filtration system have a purification rate of only 50%, while the VIOMI Master M1 achieves an impressive 75%, which can produce only 1 cup of waste water for every 3 cups of pure water produced. With a 3:1 wastewater ratio, it significantly reduces water wastage.
- 【Tankless Design】 Viomi reverse osmosis water filter saves 65% of under-sink space. You can quickly install your water purifier within 20 minutes with the help of our 4-step easy installation guide. (Note:Viomi under sink water filter requires an electrical outlet and drilling at least two holes during installation, 1″-1.5″ hole for faucet and 1/4″ hole for waste water.) Product size is 17.1”D x 6.4”W x 15.9”H.
- [ NSF/ANSI standard 42 & 53 & 58 & 372 certified ] This tankless reverse osmosis system is certified by IAPMO R&T against NSF/ANSI 58 for reduction of TDS; NSF 42 & 53 to reduce chlorine, bad taste, odor and so on. Besides, the system is certified by NSF/ANSI 372 for lead-free materials.
- [ 800 GPD high capacity, 3:1 pure to drain ratio ] The Waterdrop G3P800 reverse osmosis system offers a higher water capacity (800 gallons per day), thereby meeting demands of a big family for pure water. Furthermore, by high water flow, it filters one cup of water in just 5s. By an advanced water dispensing technology, this tankless RO water filter system produces just a cup of wastewater for every three cups of filtered water produced.
- [ 10-Stage filtration ] Tested by official third-party laboratory (SGS), through 10-stage filtration, G3P800 can effectively reduce PFAS, fluoride, heavy metals like lead, chromium, iron, salts like nitrate and chloride as well as large particles and radioactive substances such as radium. Our RO system can reduce such as vinyl chloride, ethylhexyl acrylate, isobutylene, monobutyl ether, according to the reverse osmosis membrane technical manual.
- [ Smart faucet, LED function ] G3P800 is equipped with a smart faucet, by which you can get the TDS level and water quality at a glance. The lifespan of LED lamp is up to 50 years. The LED can be automatically turned on when water flows by.
- [ Stylish look, tankless design ] The RO system G3P800 has a stylish look. The tankless design saves under sink space and ensures the safety of water. The system can consistently produce water and ensures purity in every drop. You can get purified water anytime without waiting.
- 💧IS YOUR WATER SAFE TO DRINK? Studies continue to pour in regarding Toxins, Hormones, Microplastics, Cancer-linked contaminants, known Carcinogens and other toxins discovered in our Tap Water, Filtered Water…and yes, even Bottled Water. AQUATRU’s patented Ultra Reverse Osmosis water filtration system is CERTIFIED to remove harmful contaminants.
- 💧TESTED AND CERTIFIED by IAPMO according to NSF/ANSI standards to remove 83 CONTAMINANTS – that’s 15X more contaminants than the leading pitcher filters. Removes such toxins as PFAS ‘Forever Chemicals’, Lead, Chromium, Fluoride, Chlorine and many more…
- 💧NO PLUMBING OR INSTALLATION required – takes just minutes to set up. AquaTru’s Trusted & warrantied RO countertop system COSTS CONSIDERABLY LESS than buying fully installed under-the-counter RO systems, bottled water or traditional fridge or pitcher filters.
- 💧64 oz. GLASS CARAFE for easy plastic-free pouring and sleek control panel with change filter and maintenance alerts. COST-EFFECTIVE and ENVIRONMENTALLY FRIENDLY. Best for Singles/Couples. Great for small countertop spaces, offices, dorm rooms, kitchenettes, and more.
- 💧QUICK CHANGE INSERT AND SNAP FILTERS come included with your first AquaTru water purifier and last from 6 months to 2 years. For replacement filters, only purchase the ones fitted for the Carafe (Not AquaTru Classic, Connect or Under Sink Models)
Top 9 Best Under Sink Reverse Osmosis Systems Reviews
Now that you understand the benefits and factors to consider, let’s explore the top 9 under sink reverse osmosis systems
APEC Water Systems ROES-50
The APEC Water Systems ROES-50 is a top-tier 5-stage reverse osmosis system designed for superior water quality. With its WQA certification and premium components, this system removes up to 99% of impurities, including arsenic, chlorine, lead, and fluoride. Its user-friendly design and noise-free operation make it a great choice for households seeking reliable and efficient water filtration.
Pros:
- WQA certified for superior water quality
- Removes up to 99% of impurities like arsenic, chlorine, lead, and fluoride
- User-friendly design and noise-free operation
- Reliable and long-lasting components
Cons:
- Requires frequent filter replacements, which can be costly over time
- May have a slower flow rate compared to some other models
Waterdrop G3 Reverse Osmosis System
The Waterdrop G3 is an 8-stage tankless reverse osmosis system that combines advanced filtration with intelligent features. Certified by NSF/ANSI for TDS reduction and lead-free materials, this system effectively removes a wide range of contaminants, including PFAS, radium, and chlorine. Its smart display faucet and high capacity make it an excellent choice for larger households.
Pros:
- NSF/ANSI certified for TDS reduction and lead-free materials
- Effectively removes a wide range of contaminants, including PFAS and radium
- Smart display faucet with filter life tracker
- High capacity of 600 GPD
Cons:
- Requires an under-sink electrical outlet
- Replacement filters may be more expensive than some other brands
Express Water RO5DX Reverse Osmosis System
The Express Water RO5DX is a 5-stage reverse osmosis system that delivers clean, safe drinking water without the hassle of professional installation. With its user-friendly design and leak detection feature, this system ensures a seamless and worry-free experience. Its ability to reduce up to 99.99% of contaminants, including lead, chlorine, and fluoride, makes it an excellent choice for health-conscious households.
Pros:
- Easy DIY installation, no professional required
- Removes up to 99.99% of contaminants like lead, chlorine, and fluoride
- Leak detection feature for added safety
- Cost-effective option
Cons:
- Fewer filtration stages compared to some other models
- May have a lower flow rate and capacity
iSpring RCC7AK-UV RO System
The iSpring RCC7AK-UV is a 7-stage reverse osmosis system that combines advanced filtration with UV sterilization. Certified to NSF/ANSI 58, this system effectively removes a wide range of contaminants, including PFAS, chlorine, and lead. Its UV stage provides an additional layer of protection against microorganisms, ensuring that your drinking water is not only pure but also safe.
Pros:
- NSF/ANSI 58 certified for contaminant removal
- UV sterilization stage for added protection against microorganisms
- Effectively removes PFAS, chlorine, and lead
- Clear filter housing for easy inspection
Cons:
- Requires an electrical outlet for UV stage
- More expensive than some other RO systems without UV
SimPure Tankless UV Reverse Osmosis System
The SimPure Tankless UV Reverse Osmosis System is a high-performance, space-saving solution that meets NSF/ANSI 58 standards. With its 8-stage filtration process and UV sterilization, this system delivers near-zero TDS water while effectively removing contaminants, including viruses, bacteria, and heavy metals. Its tankless design and built-in pump make it a convenient and efficient choice for modern households.
Pros:
- NSF/ANSI 58 and 372 certified for quality and lead-free materials
- UV sterilization for eliminating microorganisms
- Delivers near-zero TDS water
- Tankless design saves space
Cons:
- Requires an electrical outlet for operation
- Higher initial cost compared to some other tankless RO systems
Waterdrop G2 Reverse Osmosis System
The Waterdrop G2 is a 7-stage tankless reverse osmosis system that combines advanced filtration with a space-saving design. Certified by NSF/ANSI 372 for lead-free materials, this system effectively removes contaminants, including PFAS, PFOA, PFOS, and radioactive substances. With a high capacity of 400 GPD and a low 1:1 pure-to-drain ratio, it offers a fast water flow rate while minimizing water waste.
Pros:
- NSF/ANSI 372 certified for lead-free materials
- High capacity of 400 GPD with fast flow rate
- Low 1:1 pure-to-drain ratio for water efficiency
- Space-saving tankless design
Cons:
- Requires an under-sink electrical outlet
- Frequent filter replacements needed
iSpring RCC7AK Alkaline RO System
The iSpring RCC7AK is a 6-stage alkaline reverse osmosis system that not only purifies water but also restores its natural alkalinity and mineral balance. Certified to NSF/ANSI 58, this system removes up to 99% of contaminants, including PFAS, chlorine, fluoride, and lead. Its alkaline remineralization filter ensures that your drinking water has a balanced pH and a great taste, making it a healthier choice for your household.
Pros:
- NSF/ANSI 58 certified for contaminant removal
- Alkaline remineralization filter for balanced pH and taste
- Clear filter housing for easy inspection
- Low maintenance requirements
Cons:
- Larger footprint than some other under-sink models
- May have a slower flow rate compared to tankless systems
iSpring RCC7 High Capacity RO System
The iSpring RCC7 is a high-capacity, 5-stage reverse osmosis system designed to deliver an abundant supply of clean, refreshing water. Certified to NSF/ANSI 58, this system effectively removes over 1,000 contaminants, including PFAS, chlorine, fluoride, and lead. With its clear filter housing, leak-free design, and low maintenance requirements, the iSpring RCC7 is an excellent choice for larger households or offices.
Pros:
- NSF/ANSI 58 certified for contaminant removal
- High capacity of 75 GPD for larger households or offices
- Clear filter housing for easy inspection
- Leak-free design with check valve
Cons:
- Requires a storage tank, taking up more under-sink space
- More expensive than some other 5-stage RO systems
Slevoo Tankless Reverse Osmosis System
The Slevoo Tankless Reverse Osmosis System is a 7-stage filtration system that combines high efficiency with a space-saving design. Certified by NSF/ANSI 58 and conforming to NSF/ANSI 372 standards, this system effectively reduces TDS, PFAS, fluoride, heavy metals, and other contaminants. With its high capacity of 600 GPD and intelligent reminder faucet, the Slevoo Tankless RO System offers a convenient and efficient water filtration solution.
Pros:
- NSF/ANSI 58 and 372 certified for quality and lead-free materials
- High capacity of 600 GPD with fast flow rate
- Intelligent reminder faucet for filter changes
- Space-saving tankless design
Cons:
- Requires an under-sink electrical outlet
- Limited information on brand reputation and customer support
What is a Reverse Osmosis System?
A reverse osmosis system is a type of water filtration system that uses a semi-permeable membrane to remove contaminants from water. The process works by applying pressure to force water molecules through the membrane, leaving behind dissolved solids, such as salts, minerals, and other impurities. The result is clean, pure water that is free from most contaminants.
Benefits of Under Sink RO Systems
While there are various types of water filtration systems available, under sink reverse osmosis systems offer several advantages that make them a popular choice for many households.
Improved Water Quality
One of the primary benefits of an under sink RO system is the significant improvement in water quality. These systems can remove up to 99% of contaminants, including lead, chlorine, fluoride, arsenic, and other harmful substances, ensuring that your drinking water is safe and free from impurities.
Cost Savings
While the initial investment in an under sink RO system may seem substantial, it can actually save you money in the long run. By providing clean, filtered water directly from your tap, you can reduce or eliminate the need to purchase bottled water, which can be costly over time.
Convenience
Under sink RO systems are installed directly under your kitchen sink, providing you with convenient access to filtered water whenever you need it. No more lugging heavy bottles of water or refilling pitchers – just turn on the faucet, and enjoy fresh, clean water.
Eco-Friendly
By reducing your reliance on bottled water, you can significantly reduce your environmental impact. Bottled water production and transportation contribute to greenhouse gas emissions and plastic waste, making under sink RO systems a more eco-friendly option.
Factors to Consider When Buying an Under Sink RO System
With the numerous options available in the market, choosing the right under sink RO system can be a daunting task. Here are some important factors to consider:
Filtration Stages
Under sink RO systems typically consist of multiple filtration stages, each designed to remove specific contaminants. The more stages a system has, the more effective it will be in removing impurities. Look for systems with at least five stages, including a sediment filter, carbon block filter, reverse osmosis membrane, and post-filters.
Flow Rate and Capacity
The flow rate and capacity of an under sink RO system will determine how much filtered water it can produce and how quickly. If you have a larger household or higher water consumption needs, opt for a system with a higher flow rate and capacity.
Installation Requirements
While under sink RO systems are generally easy to install, some models may require additional components or modifications, such as a dedicated water line or a drain line. Consider the installation requirements and ensure that your kitchen setup can accommodate the system.
Certifications and Warranty
Look for under sink RO systems that are certified by reputable organizations, such as the Water Quality Association (WQA) or NSF International. These certifications ensure that the system meets specific performance and safety standards. Additionally, consider the warranty offered by the manufacturer, as it can provide peace of mind and protection against potential defects or malfunctions.
Installation and Maintenance Tips
While under sink reverse osmosis systems are designed for easy installation, there are a few tips to ensure a smooth process and optimal performance:
- Read the manufacturer’s instructions carefully and follow them step-by-step.
- Ensure that you have the necessary tools and fittings for the installation.
- If you’re unsure about any part of the installation, don’t hesitate to seek professional assistance.
- Regularly replace the filters according to the manufacturer’s recommendations to maintain the system’s efficiency.
- Perform routine maintenance checks, such as inspecting the filters and checking for leaks.
FAQs
Can under sink RO systems remove bacteria and viruses?
While standard RO systems are effective at removing most contaminants, they may not completely eliminate bacteria and viruses. For added protection, consider systems with UV sterilization or additional disinfection stages.
How often do I need to replace the filters?
The frequency of filter replacement depends on the specific system and your water usage. Most manufacturers recommend replacing the pre-filters every 6-12 months and the reverse osmosis membrane annually.
Can I install an under sink RO system myself?
Many under sink RO systems are designed for DIY installation, but the process may vary in complexity based on the model and your plumbing setup. If you’re unsure, it’s best to seek professional assistance to ensure proper installation.
Do under sink RO systems waste a lot of water?
While RO systems do produce some wastewater, modern systems are designed to be more efficient, with low pure-to-drain ratios. Some tankless models can further reduce water waste.
How long do under sink RO systems last?
With proper maintenance and timely filter replacements, most under sink RO systems can last 5-10 years or longer. Regular usage, water quality, and proper care can impact the lifespan of the system.
Conclusion
Investing in an under sink reverse osmosis system is a smart choice for households that prioritize access to clean, safe drinking water. With the wide range of options available, there is a system that can cater to your specific needs and preferences. By considering factors such as filtration stages, flow rate, capacity, and certifications, you can make an informed decision and enjoy the numerous benefits that these systems offer.
