Waterdrop G3P600 review
Waterdrop G3P600 Reverse Osmosis Water Filter System, 600 GPD Tankless RO
By Tom Calder
The G3P600 is a serious piece of kit: 8-stage filtration certified by IAPMO R&T to NSF/ANSI standards, in a tankless housing that saves cupboard space, with a 2:1 pure-to-drain ratio that wastes noticeably less water than most rival RO systems. It's a proper plumbing job rather than a tap-end gadget, so budget for the space, a drain connection and a mains socket — and factor in the separate remineralisation cartridge if you want the minerals put back.
- Best for
- Households wanting mains-fed, tankless RO filtration for taste, scale and lead-pipe peace of mind, with space under the sink for a proper plumbed install.
- Skip it if
- You just want a simple fix for taste or limescale
as of 4 Nov 2026, 19:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.We earn a commission if you buy through the retailer links on this page. It doesn't change our verdict. How we make money →
Researched, not used. We haven't used this product. This review is built from the maker's specifications, owner reports and our own sizing.
What we like
- Filtration certified by IAPMO R&T to NSF/ANSI 42, 53 & 58 for its listed reduction claims
- Tankless design frees up under-sink cupboard space versus tanked RO systems
- 2:1 waste ratio is more water-efficient than the 3:1–4:1 typical of cheaper RO units
Worth knowing
- Needs a nearby drain connection and mains power socket — a proper install, not a quick retrofit
- Remineralisation filter (to restore minerals RO strips out) is sold separately, adding to running cost
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Our review
Waterdrop's flagship tankless reverse-osmosis unit: a pump-driven, eight-stage box making drinking water on demand at up to 600 US gallons (about 2,270 litres) a day, with one litre to drain for every two kept. What matters most is the paperwork: IAPMO R&T certifies it to NSF/ANSI 42, 53 and 58 for its reduction claims, which the cheaper G2P600 lacks. For households wanting certified low-TDS water, with a drain and socket under the sink.
What it is
Eight stages, by Waterdrop's count, ending in a reverse-osmosis membrane rated at 0.0001 micron, housed in a single upright cabinet 46.0 cm wide, 14.4 cm deep and 45.0 cm tall that weighs 14.7 kg. There is no storage tank: a pump pushes water through the membrane as you open the tap, which is why Waterdrop quotes a rate (600 gallons a day, or an 8 oz cup in about 8 seconds) rather than a tank size. The tap's display shows live TDS and filter state.
Certification is what separates it from the G2P600. IAPMO R&T has tested it to NSF/ANSI 42 (taste, odour and chlorine), 53 (health contaminants such as lead) and 58 (reverse-osmosis performance), plus NSF/ANSI/CAN 372 for lead-free materials. Those are American standards rather than WRAS approval, but they are independent and specific to Waterdrop's published claims.
In a British kitchen
The pump is why this suits UK pressure better than a passive RO system: Waterdrop rates it from 14.5 to 87 psi (1 to 6 bar). Ofwat's legal minimum at the pipe serving your home is only 0.7 bar, so a poorly supplied property should measure first. You need a cold-feed connection, a drain saddle on the waste pipe (supplied), a socket for the power adapter, and about an inch of clearance around the cabinet to keep pump vibration off the cupboard. Waterdrop puts the DIY install at 30 minutes; WRAS approval is not stated, so a WaterSafe plumber is the cautious route for the backflow protection the Water Fittings Regulations require.
Noise: Waterdrop says it will not exceed 65 dB under lab conditions across that pressure range, and because there is no tank the pump works when you draw water rather than as a background hum.
Taste: reverse osmosis removes calcium and magnesium along with everything else, which many find flat, and this model has no mineral stage. Waterdrop sells an inline remineralisation cartridge (the MNR35, 12 months or 1,100 gallons) that it lists as fitting the G3P600; the G5P700A builds that stage in.
When the power goes off
No tank and a mains-powered pump means no filtered water in a power cut. Your ordinary cold tap still works and UK tap water is safe to drink unfiltered, so this is an inconvenience rather than a risk; if a filter is part of your outage planning, keep stored water or a gravity unit. See how to prepare for a power cut.
How it compares
Against its stablemates: the G2P600 has the same 600-gallon rating and 2:1 ratio but seven stages, a plain mechanical tap, no remineralisation and only the NSF 372 materials certificate. The G5P700A is faster at 700 gallons a day, lighter at 9.7 kg and adds the mineral stage, but carries NSF/ANSI 58 and 372 only. The tanked iSpring RCC7AK-UV adds UV and keeps working in an outage, but needs 45 psi and sends three litres to drain per litre kept.
Living with it
Three cartridges on three clocks: the CF pre-filter every 6 months or 550 gallons (about 2,080 litres), the CB carbon block every 12 months or 1,100 gallons (about 4,160 litres), and the RO membrane every 24 months or 2,200 gallons (about 8,330 litres). The tap display tells you which is due, and they twist out from the front without tools. Warranty is one year for manufacturing defects, with 30-day returns from Waterdrop's UK store.
Our verdict
Buy it if you want certified reverse osmosis without a tank filling the cupboard, your pressure is anywhere in the normal UK range, and you accept a plumbing job with a drain and a socket. Choose the G2P600 if you want the same output and can do without the performance certificates and the smart tap; choose the G5P700A if flat-tasting water would put you off. Do not buy any RO system if your complaint is only chlorine taste; a carbon filter does that for far less.
A researched review, built from the maker's specs, manual and UK listings; facts checked 21 Oct 2026. Sources: Waterdrop G3P600 product page (Waterdrop UK); Waterdrop UK: G-series under-sink reverse osmosis collection; Waterdrop MNR35 remineralisation filter (compatibility list); Ofwat: water pressure and the guaranteed standards scheme.
Who shouldn't buy this
Don't buy if you just want a simple fix for taste or limescale — this is a full plumbed system with ongoing filter costs and waste water; a jug filter or a simpler under-sink carbon block will cover most UK mains-water concerns without RO's install effort and mineral trade-offs.
Key specs
| Filter technology | 8-stage RO, 0.0001μm membrane |
| Filter life | RO membrane: 24 months / 2,200 gal |
| Flow rate | 600 GPD rated; fills an 8oz cup in ~8 seconds |
| Installation | Tankless undersink, plumbed to mains + drain |
This is a Researched review: we haven't used this product. We check every specification against at least two independent sources, re-check the UK price on a schedule where we can track it automatically, and say plainly who it isn't for. Commissions never change a rating.
If this isn’t the one
Best for Renters and homeowners who want better-tasting, chlorine-free tap water fast, without drilling a tap hole or fitting a drain line.
as of 4 Nov 2026, 19:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.
Best for Hard-water households who want a compact, tankless under-sink RO system with alkaline remineralisation and have a spot with mains power and a drain nearby.
as of 4 Nov 2026, 19:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.
Best for Hard-water households who want compact, tankless under-sink filtration and don't mind the plumbed install.
as of 4 Nov 2026, 19:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.Questions
Does the Waterdrop G3P600 need electricity?
Yes. A pump drives water through the membrane, and the smart tap display is powered too. It comes with a power adapter and needs a socket under or near the sink. In a power cut it produces nothing.
How loud is the Waterdrop G3P600?
Waterdrop says no more than 65 dB under standard lab conditions at 14.5 to 87 psi, and as a tankless unit it makes water as you draw it. Waterdrop advises about an inch of clearance to keep vibration off the cupboard.
How much water does the Waterdrop G3P600 waste?
Waterdrop rates it at 2:1 pure to drain, so one litre goes down the waste pipe for every two litres you drink. The unpumped iSpring we review, by comparison, sends three litres to drain per litre kept.
Does the Waterdrop G3P600 put minerals back?
Not as standard. The eight stages end at the membrane and a post-carbon polish, so calcium and magnesium are removed and not replaced. Waterdrop's MNR35 inline remineralisation cartridge can be added, or the G5P700A has the stage built in.
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