Waterdrop G3P800 Tankless Reverse Osmosis Water Filter System, 800 GPD

Why it's worth it

The G3P800 is a tankless reverse osmosis system that skips the storage tank and still puts out 800 gallons a day. It's certified against NSF/ANSI 58, 42, 53 and 372, and it sends far less water down the drain than the tank systems most people picture.

Losing the storage tank is the single best thing about this system. A traditional RO setup parks a pressurized tank in your cabinet, and that tank sits full of standing water for days. The G3P800 filters on demand instead. You get a slim upright box, room left over for the dish soap and the trash pull-out, and water that was purified seconds before it hit your glass.

Certification is the part most shoppers skim, and it's the part that matters. This system is certified by IAPMO R&T against NSF/ANSI 58 for TDS reduction, and against NSF/ANSI 42 and 53 for chlorine, taste and odor. The materials are certified lead-free under NSF/ANSI 372. Waterdrop also publishes third-party SGS testing across the ten stages covering PFAS, fluoride, lead, chromium, nitrate and radioactive particles.

From our review of 7 under-sink water filtration systems

What we like

• +Losing the storage tank is the single best thing about this system
• +Certification is the part most shoppers skim, and it's the part that matters
• +Flow is what you notice daily
• +The waste ratio is where tankless RO earns its keep

What to know

• –You need a hole in the sink deck for the dedicated faucet
• –Like every RO system without a remineralization stage, this one takes the calcium and magnesium out along with everything else
• –The filters are proprietary, and they cost more than the generic cartridges that fit older standard housings