Waterdrop G3P600 Reverse Osmosis Water Filter System, 600 GPD Tankless RO review
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.
By Tom Calder · Price last checked 20 Sep 2026, 12:29 BST · price-tracked
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.
as of 20 Sep 2026, 12:29 BST · Details
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- 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
- 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
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 |
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Alternatives to consider
as of 20 Sep 2026, 12:29 BST · 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.as of 20 Sep 2026, 12:29 BST · 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.Want this cheaper?
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