Quick verdict
A fit for households that can accommodate plumbing, drain and power requirements. Not a drop-in countertop solution.
At a glance
| Format | Tankless under-sink reverse osmosis |
|---|---|
| Rated output | 600 GPD (manufacturer rating) |
| Drain efficiency | 2:1 pure-to-drain claimed by manufacturer |
| Filters | G3-N1CF (approx. 6 months), G3-N3CB (12 months), G3P600-RO (24 months) |
| Installation | Powered unit, water feed, drain, dedicated faucet |
What everyday use looks like
The G3P600 is designed for a fixed kitchen installation. Once properly fitted, filtered water comes from a separate smart faucet; there is no countertop reservoir to refill.
Before ordering, measure the cabinet with enough extra space for tubing, ventilation and filter replacement. The manufacturer lists a 46.0 × 14.4 × 45.0 cm appliance; confirm the orientation and fitting requirements from the manual.
Ongoing maintenance
Waterdrop lists three replacement cartridges and their nominal lifespans. At the retailer-listed example prices checked in November 2026 — £31 for the six-month CF, £31 for the annual CB and £109.99 for the two-year RO — a long-run annualised filter allowance is roughly £148, before fitting, electricity or water. Real replacements vary with use and water conditions.
Use the running-cost calculator for a transparent estimate with editable assumptions.
Reasons to skip it
It is not a great fit if you cannot drill or install a tap, lack an accessible drain or electrical socket, or primarily want to improve the taste of otherwise safe mains water at minimal cost.
Our decision checklist
- Measure your available space, including access for filter changes.
- Check the official installation and filter manual.
- Verify prices, included filters, warranty and delivery at checkout.
- Look up your water provider's quality report before assuming RO is necessary.
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Sources & verification
Facts below are taken from the linked sources; product information may change. Last editorial check: 13 November 2026. No hands-on product testing was performed.