Waterdrop G3P800 review: is it the right RO system for you?
- Jun 11
- 9 min read
Updated: Jun 17
If you're looking for one of the highest-spec under-sink reverse osmosis systems available, chances are the Waterdrop G3P800 is already on your shortlist.
As Waterdrop's flagship G-series model, it combines exceptionally thorough filtration with a built-in UV sterilisation stage, excellent water efficiency and a compact tankless design.
But at £700-£1,000, it's a serious investment.
In this review, we'll look at what the G3P800 does well, what owners think of it, things to consider before buying, and how it compares to the G3P600, so you can decide whether it's the right investment for your home.
Quick verdict
If you want one of the highest-spec under-sink reverse osmosis systems available, the Waterdrop G3P800 is hard to fault.
Combining exceptional filtration, built-in UV sterilisation and excellent water efficiency, we think it's one of the best under-sink RO systems currently available in the UK.
At a glance
What customers say
Because the G3P800 is still relatively new in the UK, we've looked at the much larger pool of US Amazon reviews to get a better picture of long-term owner experiences.
At the time of writing, the system has an average rating of 4.6 out of 5 stars from more than 1,000 reviews.
What owners like
The most common themes are:
Excellent water quality
Many customers say the water tastes cleaner and better than bottled water.
Straightforward installation
Owners frequently describe the setup process as easier than expected.
Strong flow rate
Buyers appreciate how quickly the system produces water compared with older reverse osmosis systems.
Great taste
Improved taste is one of the most frequently mentioned benefits.
Compact tankless design
Many reviewers like how little cupboard space the system occupies.
Overall, the reviews suggest the G3P800 delivers what most buyers are hoping for: exceptionally clean, great-tasting water and a more modern reverse osmosis experience than traditional tank-based systems.
Common complaints
No product is perfect, and a few criticisms come up repeatedly:
The upfront cost
Some reviewers feel it's expensive, although many believe the performance justifies the price.
Pump noise
While plenty of owners describe the system as quiet, others report that the pump can be noticeable when it's running.
Occasional reliability issues
A small number of customers mention faults or units that stopped working properly.
Our take
Looking across more than 1,000 customer reviews, the overall picture is very positive. The standout themes are water quality, taste and convenience, which are arguably the reasons most people are considering a reverse osmosis system in the first place.
The few negatives that do appear — mainly price, noise and the occasional faulty unit — are fairly typical of premium under-sink filtration systems and don't seem to outweigh the overwhelmingly positive feedback.
Looking for a Waterdrop discount code? Waterdrop is currently offering Hard Water Home readers an exclusive 5% discount on the G3P800. Simply enter code HWHUK5 at checkout.
What is Waterdrop like as a brand?
Whenever you're spending several hundred pounds on a filtration system, it's worth considering what happens if something goes wrong.
In our analysis of 100 Waterdrop customer reviews, one thing that stood out was how often owners praised the company's customer service. Several buyers who experienced faults or leaks reported that Waterdrop supplied replacement parts or resolved issues quickly.
No brand is perfect, but overall we came away with the impression that Waterdrop takes after-sales support seriously.
If you'd like a deeper look at what owners think of the brand, including the most common complaints and positive themes, we've analysed 100 Waterdrop customer reviews in detail.
What we like about the G3P800
It removes the minerals responsible for limescale
For hard water homes, this is one of the biggest advantages.
Because reverse osmosis removes calcium and magnesium, water coming from the dedicated RO tap won't form limescale.
If you fill your kettle exclusively from the G3P800 tap, you should see little to no scale build-up over time.
That's something most jug filters, on-tap filters and inline filters simply can't achieve.
The UV stage adds another layer of reassurance
Reverse osmosis already removes the vast majority of contaminants.
The G3P800 goes a step further with a built-in UV sterilisation stage, designed to help reduce bacteria and microorganisms after filtration.
For many UK households, this may simply provide additional peace of mind.
It wastes less water than many RO systems
All reverse osmosis systems produce wastewater.
However, the G3P800's 3:1 pure-to-drain ratio is among the most efficient we've seen.
In simple terms, for every three litres of filtered water produced, only one litre is sent to drain.
That's significantly better than many traditional RO systems and helps reduce one of the main drawbacks of reverse osmosis.
The smart tap is genuinely useful
Some "smart" features feel gimmicky.
The G3P800's faucet display is one of the exceptions. It shows:
Filter life.
Water quality (TDS).
System status.
This makes it easier to stay on top of maintenance and gives users confidence that they're getting the water quality they paid for.
Filter changes are simple
One of the frustrations with older reverse osmosis systems is maintenance.
The G3P800's cartridges twist in and out in seconds without specialist tools.
Reverse osmosis systems only perform well when they're maintained properly, and Waterdrop has done a good job of making filter replacement straightforward.
Things to consider
The upfront cost and installation
At around £700-£1000, the G3P800 sits firmly at the premium end of the market.
The brand says installation can be completed in around thirty minutes, but many homeowners may prefer professional installation.
The system needs connecting to your cold water supply and waste pipe, and you'll also need a hole drilled in your worktop or sink for the dedicated RO tap.
If there's no power socket nearby, you may also need an electrician to add one.
You'll need a separate tap
The G3P800 comes with its own dedicated drinking water tap.
For many people that's a benefit, but it does mean drilling a hole for the tap. Depending on your kitchen, this may be through the worktop, the sink itself or the flat area behind the sink.
This is usually straightforward with laminate worktops and stainless steel sinks, although quartz, granite and other stone surfaces may require specialist tools and a little more care.
Reverse osmosis still produces wastewater
Although the G3P800 is extremely efficient by RO standards, it still produces wastewater.
That's simply part of how reverse osmosis works.
If producing no wastewater is a priority, a conventional under-sink filter may be a better fit, although it won't provide the same level of filtration.
Why does UV sterilisation matter?
Reverse osmosis already removes the vast majority of contaminants found in drinking water, including limescale-causing minerals, fluoride, PFAS, heavy metals and microplastics.
The G3P800 goes a step further by adding a built-in UV sterilisation stage.
UV water purification uses ultraviolet light to help neutralise bacteria and other microorganisms after the reverse osmosis process. Unlike chemical disinfectants, UV treatment doesn't change the taste or smell of the water.
Who benefits most from UV sterilisation?
The G3P800's UV stage may be particularly appealing if:
You have babies or young children at home.
You have elderly relatives in the household.
Someone in the home has a weakened immune system.
You use a private water supply or simply want an extra layer of protection.
You prefer a "buy once, buy right" approach and want a top spec system.
Think of the UV stage less as solving a weakness in reverse osmosis and more as adding an extra safety net.
If none of those points really resonate with you, the G3P600 may represent better value. It provides the same highly filtered, limescale-free drinking water and remains one of the best-value reverse osmosis systems in Waterdrop's range.
Waterdrop G3P600 vs G3P800
When comparing the Waterdrop G3P600 vs G3P800, you're really comparing the two strongest systems in Waterdrop's G-series range.
The G3P600 remains one of the best-value reverse osmosis systems available and will be more than enough for many households. In fact, both the G3P800 and G3P600 remove limescale-causing minerals, fluoride, PFAS, heavy metals and many other dissolved contaminants, while offering the same compact tankless design and smart monitoring features.
The G3P800 introduces several upgrades:
Flow rate: G3P800 is 800 GPD, while G3P600 is 600 GPD.
Water efficiency: G3P800 uses a 3:1 pure-to-drain ratio, while G3P600 uses 2:1.
Filtration: G3P800 has 10-stage filtration with built-in UV sterilisation, while G3P600 has 8-stage filtration.
Certifications: G3P800 includes NSF/ANSI 42, 53, 58 and 372, while G3P600 is certified to NSF/ANSI 42, 58 and 372.
For most households, the biggest differences are the addition of UV sterilisation and improved water efficiency.
If you have young children, elderly relatives, someone with a weakened immune system, or use a private water supply such as a well or borehole, the added reassurance of UV sterilisation may be enough to justify the roughly £300 price difference between the G3P800 and G3P600 at the time of writing.
However, if your main goal is exceptionally clean, limescale-free drinking water, the G3P600 delivers much of the same experience for less money and remains the sweet spot in the range for many buyers.
Read more in our: Waterdrop G3P600 review
Is the G3P800 right for you?
The Waterdrop G3P800 is undoubtedly a premium product — and it's easy to recommend if you want Waterdrop's flagship G-series system.
It delivers exceptionally clean drinking water, eliminates kettle limescale, wastes less water than many rival RO systems and adds the reassurance of built-in UV sterilisation.
For buyers looking for a long-term, buy-once, buy-right solution, we think it's one of the best under-sink reverse osmosis systems currently available in the UK.
That said, not everyone needs the additional UV stage. If your main goal is simply exceptionally clean, limescale-free drinking water, the cheaper G3P600 will likely be enough and remains the sweet spot in the range for many households.
Waterdrop G3P800 review FAQs
Is the Waterdrop G3P800 worth it?
If you're looking for one of the most advanced drinking water filtration systems available, we'd say yes.
The G3P800 removes limescale-causing minerals, fluoride, PFAS, heavy metals and many other dissolved contaminants, while also adding a UV sterilisation stage for extra reassurance against bacteria and microorganisms.
The premium price won't suit every budget, but for households serious about water quality, it's one of the strongest options we've found.
Does the Waterdrop G3P800 remove limescale?
Yes. The reverse osmosis membrane removes the calcium and magnesium responsible for limescale. That means kettles, coffee machines and other appliances filled exclusively from the RO tap should see little to no scale build-up over time.
Does the Waterdrop G3P800 remove fluoride?
Yes. Reverse osmosis is one of the most effective forms of domestic filtration for reducing fluoride, along with many other dissolved contaminants.
What does the UV sterilisation stage do?
The G3P800 combines reverse osmosis with a built-in UV steriliser.
While the reverse osmosis membrane removes dissolved contaminants such as fluoride, PFAS, heavy metals and limescale-causing minerals, the UV stage uses ultraviolet light to help neutralise bacteria and other microorganisms after filtration.
Because UV treatment doesn't involve chemicals, it doesn't affect the taste or smell of the water.
Is UV sterilisation necessary in the UK?
Not necessarily. Mains drinking water in the UK is already treated and considered safe, and reverse osmosis alone provides extremely thorough filtration.
For many households, the UV stage simply provides an additional layer of reassurance rather than solving a specific problem.
It may be particularly appealing to families with young children, elderly relatives, people with weakened immune systems, or anyone who wants Waterdrop's most advanced system.
How long does the UV steriliser last?
Waterdrop doesn't specify a separate replacement schedule for the UV module, and it forms part of the system rather than a filter that requires routine changing.
The main maintenance requirements are the three filter cartridges. As long as these are replaced on schedule, the UV sterilisation stage should continue operating alongside the rest of the system.
How much do Waterdrop G3P800 replacement filters cost?
The G3P800 uses three filters:
CF filter – replaced every 6 months (around £30-£35)
CB filter – replaced every 12 months (around £30-£35)
RO membrane – replaced every 24 months (around £120-£140)
Based on current prices, ongoing running costs work out at roughly £145-£165 per year, although prices do change over time.
Is the Waterdrop G3P800 better than the G3P600?
The G3P800 adds several upgrades over the G3P600, including:
Faster 800 GPD flow rate.
A more efficient 3:1 pure-to-drain ratio.
10-stage filtration instead of 8 stages.
Additional NSF certifications.
Built-in UV sterilisation.
For many households, however, both systems provide excellent drinking water quality. The decision largely comes down to whether you value the extra efficiency and additional peace of mind offered by the UV stage.
All prices and spec correct at time of publication 11.06.26.
Author bio: Lucinda Smalley is the founder of Hard Water Home, a UK-based consumer site helping households in hard water areas understand the challenges and solutions more easily — and make smarter choices for their health and homes. Based in Poole, she also co-runs an award-winning plumbing company, giving her first-hand insight into how water quality affects everything from appliances to skin and hair. When she’s not writing, she’s happiest at the beach with her family and a good cup of coffee (minus the floaty bits!). More about us ➡
