Under sink reverse osmosis (RO) systems are one of the most effective ways to purify your home’s drinking water. These systems sit discreetly under your kitchen sink and use a series of filters and a semi-permeable membrane to remove a wide array of contaminants. Whether you’re dealing with chlorine taste, hard water, heavy metals, or just want peace of mind, these RO systems can deliver crisp, clean, and safe drinking water on demand.
Below are the top-selling under sink RO systems on Amazon in 2025, selected for their high performance, customer satisfaction, and reliability. Each one has been reviewed in detail to help you choose the right one for your home.
Disclosure: As an Amazon Associate, I earn from qualifying purchases. This post may contain affiliate links.
Waterdrop G3P600 Tankless RO System
Rating: 4.5/5 stars
The Waterdrop G3P600 is a high-performance, tankless reverse osmosis system with an upgraded 600 GPD (gallons per day) flow rate, offering clean, filtered water on demand without the need for a bulky storage tank. It features an 8-stage deep filtration process that removes contaminants including chlorine, lead, arsenic, fluoride, heavy metals, PFAS, and total dissolved solids. The integrated smart LED faucet displays real-time TDS levels, so you know exactly how clean your water is every time you pour a glass.
Installation is straightforward, with push-to-connect fittings and an ultra-slim design that saves space under the sink. Filter replacement is easy thanks to twist-and-pull cartridges, and a color-coded reminder system tells you when each filter needs changing. The G3P600 also includes a built-in booster pump to maintain consistent flow rate and pressure. This model is ideal for families who want advanced filtration without sacrificing space or convenience.
- Pros:
- Space-saving tankless design
- Fast 600 GPD flow rate
- 8-stage filtration including PFAS removal
- Real-time TDS monitoring
- Built-in booster pump for consistent pressure
- Cons:
- Higher upfront cost
- Requires electricity to operate
- No remineralization filter (unless added separately)
iSpring RCC7AK 6-Stage RO System
Rating: 4.7/5 stars
The iSpring RCC7AK is a highly rated 6-stage system that adds beneficial minerals back into your water after filtration. This remineralization process helps improve taste and balance pH levels, which is especially appreciated by those who dislike the flat taste of demineralized RO water.
Installation is beginner-friendly with color-coded tubing and clear instructions, and the system includes a dedicated faucet and durable storage tank. Maintenance is straightforward, with long-lasting filters and a transparent first-stage housing that lets you visually inspect sediment buildup.
- Pros:
- – Adds minerals for improved taste
- – Excellent customer support
- – DIY-friendly setup
- Cons:
- – Takes up moderate under-sink space
- – No UV or smart features
Express Water RO5DX 5-Stage RO System
Rating: 4.6/5 stars
The Express Water RO5DX is a value-packed 5-stage RO system that removes up to 99.99% of major contaminants, including chlorine, lead, fluoride, nitrates, arsenic, and more. It comes with a complete installation kit and a second set of replacement filters included, making it a standout for budget-conscious buyers.
DIY installation is simple and well-documented. Filters use quick-connect fittings, and the standard tank provides a good flow rate at the faucet. While it doesn’t include high-tech extras, it delivers high performance at a very competitive price.
- Pros:
- – Great value with extra filters included
- – Simple installation
- – Removes a wide range of contaminants
- Cons:
- – No remineralization or UV
- – Bulkier than tankless systems
iSpring RCC7AK-UV 7-Stage RO System with UV
Rating: 4.5/5 stars
This enhanced version of iSpring’s system includes a UV sterilizer stage, making it ideal for homes with well water or those concerned about bacteria and viruses. It also includes an alkaline filter to reintroduce healthy minerals after filtration.
The UV light operates automatically and adds another level of safety. While installation takes a bit longer due to the extra UV module, the added protection is worth it for many users. It’s a great system for health-focused households.
- Pros:
- – Includes UV for biological safety
- – Adds minerals for taste
- – Strong all-around protection
- Cons:
- – Installation is more involved
- – UV bulb requires occasional replacement
Home Master TMHP HydroPerfection
Rating: 4.7/5 stars
The Home Master TMHP combines RO filtration, UV purification, and remineralization in one robust system. It’s designed for high-demand households and can remove nearly all common water contaminants, including heavy metals, chlorine, and microbes.
What sets this system apart is its modular design—filters come in built-in housings, so they’re incredibly easy to change without needing a wrench or dealing with mess. It’s one of the most complete systems you can get, and the water quality is outstanding.
- Pros:
- – Combines RO, UV, and remineralization
- – Easy modular filter replacements
- – High output for larger households
- Cons:
- – Higher cost
- – Requires more space under sink
APEC ROES-50 5-Stage RO System
Rating: 4.7/5 stars
A trusted name in RO systems, the APEC ROES-50 is engineered and assembled in the USA and built for reliability. Its 5-stage design removes 99% of contaminants including chlorine, lead, arsenic, fluoride, and nitrates.
Installation is simple with clear instructions, and the long-lasting filters only need to be replaced every 6–12 months. It’s a solid, no-frills system that has earned thousands of positive reviews for its consistency and build quality.
- Pros:
- – Made in the USA with high build quality
- – Very easy to install and maintain
- – Long-lasting filters
- Cons:
- – No remineralization or UV
- – Basic design without modern features
Best For…
- Best for Small Spaces: Waterdrop G3P600
- Best for Taste: iSpring RCC7AK
- Best Budget Option: Express Water RO5DX
- Best for Well Water: iSpring RCC7AK-UV
- Most Reliable Basic System: APEC ROES-50
🏆Best for Overall: Home Master TMHP
Conclusion
Each of these under sink RO systems brings something different to the table. The Waterdrop G3P600 stands out for its tankless design and smart features, perfect for modern kitchens. The iSpring RCC7AK series is great for those who want better-tasting water with mineral balance. Express Water offers affordability, while the Home Master and iSpring UV systems go all-in on advanced protection.
As you shop, think about your priorities—whether that’s water taste, ease of maintenance, filtration breadth, or smart features. Consider your available under-sink space, your local water quality (especially if you’re on a well), and how often you’re willing to swap out filters.
Choosing the right system means investing in cleaner water for your family, reducing bottled water waste, and improving your day-to-day hydration experience. With any of the RO systems above, you’re well on your way to safer, fresher, and better-tasting water every time you turn on the tap.
Head back to Under Sink Reverse Osmosis (RO) Systems