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Why it’s great
Old-school reverse osmosis (RO, which pushes water through a very fine membrane to strip out dissolved solids and many contaminants) meant a big storage tank and a dribbly faucet. This one swaps the tank for a built-in pump, so water comes out at a steady clip and the whole thing sits in a slim box under the sink. shows the filtered water’s TDS reading (total dissolved solids, the minerals and salts left in the water) and tells you when filters are due, and filters twist in and out without tools. It’s a tidy way to stop hauling bottled water and get clean-tasting water right at the kitchen tap.
Bottom line
A compact, convenient tankless RO system that makes water taste noticeably better, as long as you accept the pump noise, the install work and the ongoing filter cost.
Best for
- Homeowners who are tired of buying or carrying bottled water
- Small kitchens where a bulky storage tank won’t fit under the sink
- People with high-TDS or off-tasting tap water who want a visible reading to prove it works
- Anyone who wants easy, tool-free filter swaps without pulling the system out
- Households with a free under-sink outlet and room to drill a faucet hole
Who should skip this
- Renters who can’t drill the sink or countertop. Installing the faucet needs a hole of about an inch, plus a drain connection.
- Anyone with no outlet under the sink. The unit needs power for its pump.
- Light sleepers or open-plan kitchens. Buyers describe a pump hum, and the unit flushes itself now and then.
- People who expect a tap-fast flow. One buyer warns that it fills a glass more slowly than a regular faucet.
Key features
- Output and ratio: rated at 600 gallons per day, with a 2:1 pure-to-drain ratio, meaning about one cup of wastewater for every two cups of purified water. The listing says it fills an 8 ounce cup in 8 seconds.
- Filtration: an 8-stage design using pre-filters, carbon block and a reverse osmosis membrane. The listing claims reduction of TDS, PFAS, fluoride, arsenic, chromium, radium and more, based on third-party lab testing by SGS.
- Certifications listed: NSF/ANSI 58 for TDS reduction, NSF/ANSI 372 for lead-free materials, and NSF/ANSI 42 for chlorine, taste and odor.
- Smart faucet: a display shows the filtered water’s TDS and tracks filter life. The listing offers a silver faucet, and a black faucet option appears in the selector.
- Size and install: roughly 18 by 6 by 18 inches. It needs an under-sink outlet and two drilled holes, one for the faucet and one for the drain connection. Filters twist out in about three seconds, per the listing.
- Operating limits: the spec table lists 41 to 100 degrees Fahrenheit, a maximum operating pressure of 87 psi, and feed water up to 1500 ppm TDS.
Performance and usability
- Taste and TDS drops are the headline. Buyers report tap water in the hundreds of ppm dropping to single digits, with taste they compare to or prefer over bottled water. One buyer’s handheld meter read slightly higher than the faucet’s display, so treat the display as an indicator, not a lab reading.
- Wastewater may beat the claim. Water Filter Guru tested the sibling G3P800 and measured less wastewater than the advertised ratio. That’s a different model with a different advertised ratio, so use it as a hint, not a guarantee for the G3P600.
- Expect some noise. Buyers describe a low pump hum and noise during self-cleaning. One buyer found the unit much quieter after fixing a partly blocked shutoff valve, which they think starved the pump. Another says it vibrated against the cabinet wall, so leave space.
- Install ranges from easy to fiddly. Buyers report anywhere from about 30 minutes to over 3 hours. Common snags are stiff tubing, a drain saddle that dripped until pushed in further, and the extra drilling. Pushing every fitting fully in helps prevent leaks.
- Plan for TDS creep and flush time. One buyer notes that after the system sits unused, the first water out reads higher on TDS. They run the tap for 30 to 40 seconds to clear it, and Water Filter Guru suggests checking for this during any RO purchase.
Real world use cases
- Filling coffee pots, kettles and water bottles from a dedicated faucet next to the sink
- Cooking and washing produce with low-TDS water
- Teamed with a small pressure tank for steadier flow, as one buyer did
- Adding a remineralization filter if you find plain RO water flat, as one buyer did
- Piped to a fridge water line, which some buyers report doing (check your fridge’s manual first)
- Replacing a gallon-jug habit for a household that drinks a lot of water
Pros & cons
| Pros | Cons |
|---|---|
| Tankless design that frees up under-sink space | Needs an outlet and drilled holes, and installs can take hours |
| Faucet display shows TDS and filter life | Pump hum and periodic self-flush noise |
| Tool-free twist filter changes | |
| 2:1 ratio, with a sibling model measured better than advertised | |
| Great taste and big TDS drops reported by buyers |
Trust signals
This model hasn’t been covered by the major independent review outlets, which is common for newer appliance brands in this price tier. The better evidence is the certification information, the filter schedule, the return window and the patterns in buyer feedback.
The listing names NSF/ANSI 58, 372 and 42 along with third-party lab testing, so look up the model in the certifier’s database and match the certified claims to the contaminants in your own water. Waterdrop’s replacement-filter listings put the carbon filters at roughly six months, the carbon block at about a year and the RO membrane at about two years, though your water will change that. Check the warranty terms with Waterdrop, since the page text doesn’t state them. The item is sold by WaterdropDirect and ships from Amazon, with Amazon’s standard 30-day return window at the time of writing, so check that window before you cut any holes.
Scorecard
| Category | Rating | Notes |
|---|---|---|
| Aesthetic & Form Factor | High | Slim tankless box under the sink and a clean smart faucet in silver or black. |
| Space Efficiency | High | No storage tank, though buyers note a mess of rigid tubing. |
| Performance & Speed | High | Big TDS drops reported and a steady pumped flow, if slower than a regular tap. |
| Ease of Cleaning & Maintenance | High | Tool-free twist-in filters and a display that tracks filter life. |
| Quietness | Medium | A pump hum and occasional self-flush are audible. |
| Build Quality & Durability | Medium | Metal faucet and plastic cover, with some buyers reporting leaks at fittings during install. |
| Ease of Setup / Learning Curve | Low | Drilling, drain saddle and tubing take from half an hour to a few hours. |
| Eco & Sustainability | Medium | Replaces bottled water, but sends wastewater to the drain. |
| Value / Price-to-Performance Ratio | Medium | Premium upfront cost plus recurring filters, offset by bottled water savings. |
| Portability | Low | Plumbed and plugged in, so it stays under the sink. |
What is in the box
- 1 reverse osmosis system with 3 pre-installed filters
- 1 smart display faucet (silver, or black on that version)
- 1 user manual
Final verdict
The Waterdrop G3P600 delivers what most people want from RO: clean-tasting water, a tidy under-sink footprint and filters you can swap without tools. Go in knowing it needs drilling, power and some noise tolerance, and read the certification line closely against your own water report. If that fits, it’s a strong pick.
What to know before buying
Reverse osmosis changes your water more than a basic filter does. Know what’s in your tap water and what the system is actually certified to reduce before you buy.
Q: What Matters in a Tankless Reverse Osmosis System
A: Check the certifications, the pure-to-drain ratio, flow and noise. Certifications show which contaminants the system is tested to reduce, so match them to your own water report. The ratio shows how much water goes to the drain for each cup you drink. Also confirm a free outlet, room to drill and cabinet space.
Q: How It Compares to Alternatives
A: Tank-style RO systems skip the pump but take up more space and fill slowly. Simple under-sink or pitcher filters are easier to install, but don’t reduce dissolved solids the way RO does. Water Filter Guru notes that RO systems install more slowly and waste some water.
Q: Who This Category Is Best For
A: Homeowners with hard, salty or off-tasting water who want low-TDS drinking water at the sink, and who are happy to maintain filters on a schedule.
Q: Who It’s Not Ideal For
A: Renters, people who can’t drill or plug in under the sink, and anyone sensitive to noise. A countertop or pitcher filter is a lighter-weight option for them.
Q: What to Check Before You Buy
A: Confirm the model number (G3P600, also called WD-G3), the faucet color and the dimensions against your cabinet. Look the model up in the certifier’s database to see exactly which NSF/ANSI standards apply, such as 58 for TDS reduction, and match them to your water report. Confirm the warranty terms with Waterdrop, and check the return window before you drill.
Editor’s Summary for Waterdrop G3P600 Tankless Reverse Osmosis System
Waterdrop G3P600 Tankless Reverse Osmosis Water Filter System (model WD-G3, 600 GPD, 8-stage, smart display faucet), sold with a silver faucet and also with a black faucet
The Waterdrop G3P600 is a tankless reverse osmosis system that fits under the sink and shows filter life and water quality on its faucet.
4.5
Pros
- Tankless design that frees up under-sink space.
- Faucet display shows TDS and filter life.
- Tool-free twist filter changes.
- Great taste and big TDS drops reported by buyers
Cons
- Needs an outlet and drilled holes, and installs can take hours.
- Pump hum and periodic self-flush noise.
