The Waterdrop G3P600 is a tankless reverse osmosis (RO) system that’s a strong fit for London and UK hard water. It costs £350–£550 upfront plus roughly £120–£150 a year in filters, and it’s worth it if you want much cleaner-tasting drinking water and lower TDS. It’s not worth it if you’re renting, on a tight budget, or only bothered about basic chlorine taste.
This review covers:
- What the G3P600 actually is and how it works
- How it performs on London and UK tap water
- Real installation and running costs
- Pros, cons, and genuine owner feedback
- How it compares to the G5P700A, G3P800, iSpring, and Brita
- Whether you need this or a water softener
All figures below come from Waterdrop’s published specs, NSF certification data, and current UK retailer pricing.
Quick Verdict
- Best for: London/UK homes with hard water, high TDS, chlorine taste, or PFAS concerns
- Not ideal for: renters, tight budgets, or anyone who only wants basic chlorine-taste removal
- UK price: £350–£550, depending on retailer and promotions
- Running cost: ~£120–£150 per year in replacement filters
- Rating: 4.3/5 — strong filtration and compact design, let down slightly by the price step-up from entry-level RO units
What Is the Waterdrop G3P600?
- A tankless under-sink reverse osmosis system — filters water on demand instead of storing it in a tank
- Water passes through 8 filtration stages before reaching a dedicated smart-display kitchen tap
- Tankless design saves up to 70% of under-sink space compared with tanked RO systems
- “G3” = product generation; “600” = rated output of 600 gallons per day (GPD) — a capacity rating, not your actual usage
Key Specifications
| Spec | Detail |
|---|---|
| Filtration stages | 8-stage (CF pre-filter, CB carbon block, RO membrane) |
| Output | 600 GPD, ~0.42 GPM flow rate |
| Pure-to-drain ratio | 2:1 |
| Certifications | NSF/ANSI 58 (TDS reduction), NSF/ANSI 372 (lead-free) |
| Membrane pore size | 0.0001 micrometres |
| Dimensions | 18.11″ x 5.67″ x 17.72″ (tankless) |
| Faucet | Smart LED display — TDS reading + filter life |
| Power | Mains-powered via plug adapter |
| Fill time | ~8 seconds per glass |
| Weight | 32.4 lbs (~14.7 kg) |
Water Quality and Filtration Performance
What it removes:
- TDS (total dissolved solids)
- Chlorine, taste and odour
- Fluoride
- Lead and heavy metals (arsenic, chromium)
- PFOA and PFOS (common PFAS “forever chemicals”)
- Microplastics
Certifications: Independently tested by IAPMO R&T against NSF/ANSI 58 (TDS reduction) and NSF/ANSI 372 (lead-free materials).
The 3 physical filter stages:
- CF filter — coconut shell carbon block; strips sediment, rust, chlorine taste and odour
- CB filter — second carbon stage; improves taste further, no added chemicals
- RO membrane — core filtration stage; blocks dissolved solids, heavy metals and PFAS at the molecular level
Does It Improve the Taste of London Tap Water?
- Yes, noticeably.
- London water is chlorinated and mineral-heavy, supplied via Thames Water — taste is often stronger in summer when chlorine dosing increases
- RO strips out both chlorine and dissolved minerals
- Result: cleaner, flatter taste — closer to bottled still water than jug-filtered water
TDS Reduction
- Carbon jug filters: mainly target chlorine/taste, barely touch TDS
- RO systems: physically block dissolved solids at the membrane
- Typical reduction: 90%+ TDS, depending on starting water hardness
- London hard-water boroughs: tap water often measures 250–350 ppm TDS
- Post-filtration through the G3P600: typically 15–30 ppm, shown live on the smart tap display
Is It Good for London and UK Hard Water?
- London is hard to very hard water territory — especially Richmond, Kingston, Sutton, and much of North/West London
- Hardness = dissolved calcium and magnesium, which cause limescale on kettles, taps and shower screens
Does It Remove Limescale?
- Yes — but only at its own tap.
- The RO membrane removes calcium and magnesium from water passing through the filter
- It does not treat water going to your boiler, kettle, shower or washing machine
- For whole-home limescale protection, you need a water softener (see comparison below)
- For drinking and cooking water specifically, it’s one of the most effective hard-water solutions available
Installation in London
Installation Cost
- DIY install: Free beyond the unit cost. ~30 minutes with basic tools, using the supplied drain saddle, feed water adapter and push-fit tubing
- Professional plumber install: Typically £80–£180 in London
- Cost depends on: existing under-sink plumbing, whether a new drain point is needed, and whether a tap hole needs drilling through the worktop
Installation Steps
- Turn off the water supply under the sink; confirm a nearby power socket for the mains adapter
- Fit the feed water adapter to the cold water line (compatible with 3/8″ and 1/2″ lines)
- Attach the drain saddle to the waste pipe to route away concentrate water
- Mount the tankless unit, leaving ~1 inch from the cabinet wall to reduce vibration noise
- Install the smart faucet through an existing or newly drilled tap hole
- Connect the tubing between unit, faucet and drain saddle with the supplied push-fit PE pipes
- Power on and flush before drinking, so new filters settle in
Note: Stone or granite worktops without a spare tap hole usually push installation cost toward the higher end of the range.
Running Costs
Filter Replacement Schedule
| Filter | Lifespan |
|---|---|
| CF (sediment/carbon) | Up to 6 months or 550 gallons |
| CB (carbon block) | Up to 12 months or 1,100 gallons |
| RO membrane | Up to 24 months or 2,200 gallons |
- Actual lifespan depends on local water quality and household usage
- Smart faucet display tracks filter life and alerts you when a change is due
- Replacement is tool-free: cartridges twist out, new ones twist in, in seconds
Annual Running Cost
- Budget roughly £120–£150 per year, averaged across the three replacement cycles
- Cheaper than bottled water for most families
- Lower than many tanked RO systems that need more frequent cartridge changes
Does It Waste a Lot of Water?
- All RO systems produce some wastewater — the concentrate has to go somewhere
- G3P600 ratio: 2:1 (2 litres filtered for every 1 litre to drain)
- Compares well against older tanked RO systems, which often run at 3:1 or 4:1
- Not zero-waste, but one of the more water-efficient tankless RO options in the UK
Pros and Cons
Advantages
- Compact tankless design — saves significant cupboard space
- Strong contaminant removal: TDS, chlorine, fluoride, PFAS, lead, microplastics
- Smart faucet shows live TDS reading and filter-life status
- Tool-free filter changes in seconds
- Efficient 2:1 pure-to-drain ratio
- NSF/ANSI 58 and 372 certified
- Fast fill time (~8 seconds per glass)
Disadvantages
- Higher upfront cost than jug or basic under-sink carbon filters
- Needs a nearby power socket and drain access — not every kitchen layout suits this
- Only filters water at its own tap, not the whole home
- No NSF/ANSI 53 certification or UV sterilisation (unlike the G3P800)
- Occasional reports of leaks or missing parts on arrival — customer service response generally well rated
What Owners Actually Say
- Large majority of verified UK/US buyer ratings sit at 4 or 5 stars
- Most praised: taste improvement on hard/chlorinated mains water
- Most praised: small footprint vs. previously owned tanked systems
- Most praised: smart tap TDS readout, makes maintenance easier to track
- Most common complaint: installation issues — mostly resolved via Waterdrop customer support
- Minor complaint: occasional leaks or delivery issues — worth noting if self-installing without plumbing experience
Waterdrop G3P600 vs Other Systems
vs G5P700A
- G5P700A: faster 700 GPD output, lower long-term running cost, higher upfront price
- G3P600: stronger value pick if budget-conscious
- G5P700A: better if minimising cost-per-litre over 5–7 years matters most
vs G3P800
- G3P800: adds NSF/ANSI 53, UV sterilisation, 3:1 waste ratio — costs £200–£300 more
- G3P600: sufficient if you mainly want great-tasting, low-TDS water
- G3P800: better if you want the broadest contaminant certification and don’t mind the spend
vs iSpring RCC7AK
- iSpring: tank-based, 6-stage, ~£120 cheaper
- iSpring: bulkier (needs tank space), slower fill, less efficient waste ratio
- G3P600: better if kitchen space and fill speed matter
vs Brita
- Brita: carbon-only, cheaper, no installation needed
- Brita: targets chlorine taste and some limescale minerals — minimal TDS, PFAS, fluoride or heavy metal reduction
- G3P600: different performance tier entirely for contaminant removal
| Feature | G3P600 | G5P700A | G3P800 | iSpring RCC7AK | Brita (jug/tap) |
|---|---|---|---|---|---|
| Type | Tankless RO | Tankless RO | Tankless RO | Tanked RO | Carbon filter |
| Output | 600 GPD | 700 GPD | 800 GPD | 75 GPD | N/A |
| Waste ratio | 2:1 | 2:1 | 3:1 | Higher (tank-based) | None |
| UK price | £350–£550 | Higher | £200–£300 more than G3P600 | ~£226 | £15–£40 |
| TDS reduction | High | High | High | High | Minimal |
| Best for | Space-conscious upgraders | Lowest long-term cost | Max certification/UV | Budget RO buyers | Basic taste improvement |
G3P600 or a Water Softener?
They solve different problems:
- Water softener — treats the whole home’s supply; ion-exchanges hard minerals for sodium; protects plumbing, boiler, kettle and appliances from limescale
- Waterdrop G3P600 — point-of-use system; produces very clean water at one tap only; doesn’t protect pipework elsewhere
Common London approach: many hard-water households use both — a softener for whole-home plumbing, and the G3P600 for drinking/cooking water, since softened water still carries added sodium some people prefer to filter back out.
Is the Waterdrop G3P600 Worth It?
Worth it if you:
- Live in a hard-water London/UK area
- Want a noticeable taste and TDS improvement
- Have space and budget for a mid-tier RO system
- Care about PFAS, fluoride or lead reduction
Not worth it if you:
- Are renting and can’t install fixed plumbing
- Only care about chlorine taste
- Need the absolute cheapest option
Frequently Asked Questions
Is the Waterdrop G3P600 worth it in London?
Yes, for most hard-water London homes. It cuts TDS, chlorine, fluoride and PFAS at a lower long-term cost than bottled water, though it costs more upfront than a jug filter.
Is the Waterdrop G3P600 good for London hard water?
Yes. The RO membrane removes the calcium and magnesium causing limescale and hard-water taste, but only at its own dedicated tap.
Does the Waterdrop G3P600 remove limescale?
It removes limescale-causing minerals from water passing through its own tap. It won’t stop limescale in your kettle, boiler or shower.
Does the G3P600 improve the taste of London tap water?
Yes. Most users report a cleaner, flatter taste versus London’s chlorinated, mineral-heavy mains supply.
How much does Waterdrop G3P600 installation cost in London?
DIY: free beyond the unit price, ~30 minutes. Professional plumber install: typically £80–£180.
How often do you replace G3P600 filters?
CF filter: up to 6 months. CB filter: up to 12 months. RO membrane: up to 24 months.
How much does it cost to run a G3P600?
Roughly £120–£150 per year in replacement filters.
Does the Waterdrop G3P600 waste a lot of water?
It uses a 2:1 pure-to-drain ratio — more efficient than most older tanked RO systems, though some waste is unavoidable with any RO system.
Is the G3P600 better than a standard under-sink filter?
For contaminant reduction, yes. Standard carbon filters improve taste but don’t meaningfully lower TDS, fluoride, PFAS or heavy metals.
Should London homeowners choose the G3P600 or a water softener?
Different jobs. A softener protects whole-home plumbing from limescale; the G3P600 gives highly filtered drinking water at one tap. Many hard-water households use both.
Final Verdict
- One of the strongest tankless RO systems for UK kitchens
- Handles London’s hard, chlorinated tap water well
- Reasonable running costs, small footprint
- £350–£550 upfront + ~£130/year is a fair trade for consistently cleaner drinking water
- Won’t solve limescale anywhere outside its own tap
Next step: if you’re installing in a London kitchen, get a fixed plumber quote before buying, so you know the full cost — unit plus fitting — up front.
