Waterdrop G3 Reverse Osmosis System Review (Lab Testing)

The Waterdrop G3 reverse osmosis system is a tankless unit that’s installed under a kitchen sink. In our testing, the G3 P800 did an excellent job at removing lead, fluoride, arsenic, and more. But there’s no built-in remineralization filter and the unit’s tankless design has limitations.

Overall Score: 9.21

How We Test & Score

9.28 Contaminant Reduction

9.70 Design

10.00 Maintenance

10.00 Filtration Rate

7.00 Setup

8.65 Company

What We Like

Greatly reduced 10+ contaminants with health effects in our water

Optional remineralization filter restored alkalinity & pH

Space-saving tankless design

Choice between 600 and 800 GPD flow rates

Good 3:1 efficiency ratio

IAPMO certified performance

What We Don’t Like

Expensive

No built-in remineralization filter (must be installed separately)

Hassle to install

Nitrite appeared in the filtered water in our with-remineralization test

Price	$539 – $999
Contaminants Removed	1,000+
Certifications	NSF/ANSI 42, 53, 58 & 372
Process	Mechanical + Carbon + RO
Filtration Capacity	550/ 1100/ 2900 gallons
Annual Cost	~$145
Warranty	1 year

View price for G3P800

View price for G3P600

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There are two unit configurations in the G3 range:

• The G3 P600, with a 600 gallon-per-day (GPD) flow rate
• The G3 P800, with an 800 GPD flow rate

These systems use the same filter stages and the only difference is their water production rate: the G3 P800 is the faster model. We’ll be discussing both of these systems in this review, but with a main focus on the G3 P800, since this was the system that we installed and tested ourselves.

We tested the G3 P800 as a standalone unit and with Waterdrop’s optional inline remineralization filter, which we installed downstream of the system to remineralize our water post-filtration. We’ve highlighted any differences we saw between these two configurations throughout this review. 

📊 Scoring Data

To obtain the scoring data for the water filters we review, we conduct our own testing at home. For some of our testing categories, we also obtain data from the product information and third-party testing available online. We use 6 main testing categories to rank a water filtration system, and we’ve shared the data behind the scores we assigned for the Waterdrop G3 P800 below. 

2026 Update: We’ve now made our testing process even more comprehensive. We’ve retested the Waterdrop G3 and over a dozen other RO systems, gathering additional data for efficiency ratio, TDS creep, flushing, and several other factors that matter. These provide extra context and we’ve discussed them in this review, but they’re not currently ranking factors.

Criteria	Results
Overall Score	9.21
Health Related Contaminants	9.50
Aesthetic Related Contaminants	3.50
Performance Certification	Certified for 100% of reduction claims
Filtration Rate	600 or 800 GPD
Component Quality	Outstanding
Component Certification	Certified
Setup	Weak
Servicing Requirements	Exceptional
Costs	$0.11/ gallon (w/o remineralization), $0.13/ gallon (w/ remineralization)
Warranty Length	90 days
Shipping	Free on orders over $50
Returns	30 days

🎬 Video Review

🚰 Contaminant Reduction

Score: 9.28

We tested our drinking water for contaminants before and after filtering it through the Waterdrop G3 P800, which we combined with our research into the filter’s performance certifications to attain an overall score for contaminant reduction.

Our Performance Testing

Score: 9.20

We wanted to test the Waterdrop G3 P800 in our own home to see what it could remove from our drinking water supply. 

Reverse osmosis systems purify water, removing more contaminants than a standard filter, thanks to their semi-permeable membranes. So, going into testing for the G3 P800, we expected to see a significant reduction of the contaminants detected in our feed water.

We tested our water with Tap Score and mailed our samples to the lab for professional testing. The company has a strict sample-taking protocol, which we followed closely to ensure that our results were accurate.

Our interactive report was available to view on the SimpleLab platform within a week. The report told us a few things:

• The quality of our water overall, with an assigned Tap Score from 1-99
• The contaminants detected in our water samples
• Whether these contaminants were linked to health, aesthetic, or plumbing effects

In the table below, we’ve shared the contaminants detected in our feed water and what percentage of these were removed by the Waterdrop G3 P800.

Health-Related Contaminants

Score: 9.50

Our unfiltered water contained trace levels of 14 contaminants with possible health effects: dibromochloromethane, bromodichloromethane, and bromoform (three disinfection byproducts in the THMs group), fluoride, uranium, boron, copper, nitrate, strontium, barium, selenium, total chromium, molybdenum, and vanadium. 

Of these contaminants, all three DBPs, fluoride, and uranium were present at levels that exceeded the HGL.

Some of the possible health effects associated with these contaminants include:

• Developmental outcomes
• Skeletal health issues
• Blood and nervous system effects
• Cardiovascular health problems
• Effects on kidney and liver health
• Immune effects
• Carcinogenic (cancer-causing) effects
• Effects on the eyes and vision
• Gastrointestinal issues
• Reproductive outcomes
• Respiratory problems

Post-filtration, our results showed that:

• Without remineralization, G3 had eliminated all contaminants detected above the HGL, apart from fluoride, which was reduced by 78%. It also completely removed barium, copper, selenium, molybdenum, vanadium, strontium, and total chromium. The unit also reduced 75% nitrate. 
• With the added remineralization filter, the G3 eliminated all contaminants detected above the HGL, including fluoride. It completely removed barium, copper, selenium, molybdenum, and vanadium. Additionally, strontium was reduced by 97%, and total chromium by 88%.

It’s interesting to note that nitrate removal was also better with the remineralization filter (100% vs 75.76% without this added filter stage). While the primary purpose of a remin filter is to enhance the purified RO water by adding minerals, here, it appears to provide a second adsorption pass, allowing for even more thorough filtration.

What the G3 P800 Doesn’t Remove Well

There were a couple of more disappointing results that we noted: 

First, boron was reduced by just 19% (to 0.338/0.34 PPM) with both configurations. Boron reduction is a known RO membrane limitation because, in typical drinking water conditions, it exists mainly as boric acid, which is a small, neutral molecule with no charge. RO membranes are much better at rejecting charged particles like salts, so this uncharged form can pass through more easily.

Second, 0.24 PPM nitrite appeared in the filtered water in our with-remineralization test, when it wasn’t present in the baseline sample. It’s possible that this is coming from the remin cartridge. We’d need to retest to confirm, but based on this anomaly, we recommend flushing the remineralization stage thoroughly when you first install it to reduce the likelihood of this result. 

pH, Minerals, & Salts

One of the setbacks of any system that uses a reverse osmosis membrane is that it reduces the good stuff as well as the bad stuff. That’s why brands like Waterdrop sell remineralization filters that can be installed as a post-filtration stage, reintroducing healthy minerals that contribute to alkalinity and taste benefits.

Our baseline source water was aggressive, with 776 PPM TDS and 247 PPM hardness.

Post-filtration, our results highlighted the following changes to TDS, minerals, and salts in our water: 

Without remineralization:

• TDS was reduced to 35 PPM, a 95% reduction
• Hardness was reduced by 99%, to 0.91 PPM
• Calcium was reduced by 99%, to 0.36 PPM
• Magnesium dropped to 0, reduced by 100%
• Sulfate also dropped to 0, reduced by 100%
• Sodium was reduced by 94%, to 11 PPM
• Chloride was reduced by 92%, to 7.4 PPM

With remineralization: 

• TDS was reduced to 48 PPM, a 93% reduction
• Hardness was reduced by 96%, to 8.36 PPM
• Calcium was reduced by 95%, to 3.16 PPM
• Magnesium was reduced by 99%, to 0.011 PPM
• Sulfate dropped to 0, reduced by 100%
• Sodium was reduced by 94%, to 10.9 PPM
• Chloride was reduced by 93%, to 6.4 PPM

We can see the influence of the remin filter in these results. Hardness, calcium, and sodium were detected in slightly higher concentrations post-filtration, suggesting that trace levels of these minerals were reintroduced by this additional filter stage. 

As for pH, our baseline sample had a pH reading of 8.0 (slightly alkaline). Without the remineralization filter, this was reduced to 7.0 (neutral). With the remin filter, it was reduced to 7.5. This demonstrates the alkalizing effects of the remineralization filter. 

Plus, alkalinity dropped to 0 without the remineralization filter but was restored back up to 27 PPM with this filter. This is what actually drives the “taste” difference that you’ll notice if you ever drink a sample of remineralized RO water versus pure water with no minerals. 

Finally, bicarbonate (which is a dominant contributor to total alkalinity) was reduced to 0 PPM without mineralization, while 32.8 PPM was retained with the remin filter.  

TDS & TDS Creep

As well as using the TDS readings from our Tap Score data, we also measured TDS ourselves on-site using our own TDS meter. 

The purpose of our on-site testing was to see how the system affected TDS at different phases of use, and whether or not TDS creep was an issue. 

We’ve discussed this more in our guide to TDS creep here. The short explanation is that it happens when a reverse osmosis system isn’t used for a short period, and the pressure in the semi-permeable membrane equalizes, raising the TDS levels in the initial draw of filtered water.

To measure TDS creep, we let the system sit idle overnight for 10 hours. From here, we opened the faucet and filled a glass of water with the first draw sample. We immediately measured TDS with a handheld TDS meter. 

Our feed water had a TDS of 656 PPM, which is classified as “poor” by the WHO based on its effects on the palatability of water. 

The G3 had a 1st draw TDS reading of 67 PPM, which is not indicative of TDS creep, since TDS had been reduced by almost 600 PPM.

After taking the initial reading of the first draw sample, we kept the water flowing through the system for 2 minutes. We then filled a separate glass and measured the lowest stable TDS, which was 34 PPM, or 43 PPM after remineralization.

That means the G3 had a TDS creep of just 33 PPM (the difference between the 1st and 2nd draw), which is very minimal. For some perspective, some of the tankless systems we tested had a TDS creep of 400 or more. 

Aesthetic Contaminants

Score: 3.50

Our unfiltered water contained around 0.4 PPM of chlorine. This is pretty normal for municipal drinking water in the U.S. – chlorine is the most commonly used chemical for disinfection of water supplies. 

We tested our water’s chlorine content using a test strip, which gave us immediate results. We couldn’t get our water lab tested for chlorine because it’s very volatile and would dissipate before we could get the water to our lab. 

Post-filtration, we tested our water again. Our results showed that there was 0 PPM of chlorine in our purified water, so the Waterdrop G3 P800 had removed it all. 

We’d expected this outcome given that the G3 P800 uses both an activated carbon filter (AC filters are commonly employed for removing tastes and odors and are endorsed by the CDC for removing chlorine) and a reverse osmosis membrane (RO membranes reject contaminants down to 0.0001 microns). 

Performance Certifications

Score: 10.00

The Waterdrop G3 combines three filter cartridges: a carbon block and sediment pre-filter (CF), an activated carbon coconut filter (CB), and a semi-permeable RO membrane (RO). These have been IAPMO certified to NSF 42, for removing chlorine, and NSF 58 and NSF 53, for reducing TDS, fluoride, cadmium, hexavalent chromium, and selenium.

We always try to look for reverse osmosis systems with official certifications where we can because it’s reassuring to know that a filtration system has been tested and approved by an organization we can trust. We were happy with the G3’s certifications, although we would have liked to see it tested to remove more contaminants under NSF 58.

For this ranking category, we compared the contaminants removed from our own water supply with Waterdrop’s certification data.

The G3 P800 removed selenium by 100%, fluoride by 78-100%, hexavalent chromium by 88-100%, and chlorine from our water, and reduced TDS by 93-95%. Cadmium wasn’t detected in our water, so we were unable to corroborate this particular certification in our testing.

In the table below, we’ve compared our testing data with IAPMO certification data for the G3 P800. 

Contaminant	IAPMO Certification	Water Filter Guru Testing Data
Barium	NSF/ANSI 58	-100%
Cadmium	NSF/ANSI 58	Not Detected
Chlorine	NSF/ANSI 42	-100%
Fluoride	NSF/ANSI 58	-79%-100%
Hexavalent Chromium	NSF/ANSI 58	-100%
PFOA/PFOS	NSF/ANSI 53	Not Detected
Radium	NSF/ANSI 58	Not Detected
Selenium	NSF/ANSI 58	-100%
TDS	NSF/ANSI 58	-93%-95%

🚦 Filtration Rate

Score: 10.00

Filtration rate for RO systems is measured in GPD (gallons per day) rather than GPM (gallons per minute).

As a reminder, we got the Waterdrop G3 P800 under-sink reverse osmosis system, which has a water production rate of 800 gallons per day. The other option is the Waterdrop G3 P600, which has a slightly lower capacity of 600 gallons per day. The G3 P800 stood out to us in our research because its 800 GPD water production rate is the fastest we’ve ever seen. 

In our own flow rate testing, at a feed water temperature of 58.3°F*, we measured the time it took (in seconds) for the unit to fill a graduated measuring container up to a specified fill line with purified water. 

So that we could be as precise as possible with our measurements, down to the millisecond, we took video footage of the process and uploaded it onto an editing tool. We then moved through the video frame by frame until we had:

• The precise starting point (water leaving the faucet) 
• The exact ending point (container filled to the specified fill line)

We noted the average time to fill to the 12-ounce line of our measuring jug, then repeated the same test 2 additional times. The average recorded time was 9.14 seconds, translating to a flow rate of 0.62 GPM (gallons per minute), or 36.94 GPH (gallons per hour).

That’s approximately 886.54 GPD (gallons per day), which actually exceeds the manufacturer’s claimed purified water production rate of 800 GPD. Of all the RO systems we’ve tested, this Waterdrop model has the fastest recorded flow so far.

Efficiency Ratio

We found that the Waterdrop G3 P800 excels in this performance category. We’ve tested dozens of under-sink tankless reverse osmosis systems, and this Waterdrop model has one of the best efficiency ratios we’ve seen for a system of its kind.

The unit has a listed 3:1 pure-to-wastewater ratio, meaning that only 1 gallon of water is lost for every 3 gallons purified. Wastewater production is an unavoidable side effect of the reverse osmosis process, but most RO systems we’ve tested (even the modern ones) waste at least 1 gallon of water per gallon purified. 

We’ve only tested a few countertop RO systems that have 4:1 efficiency ratios, but none that offer on-demand under-sink filtration like the G3.

We conducted our own testing to measure the G3’s efficiency ratio in real-world conditions. To do this, we unhooked the end of the wastewater line and placed it inside a 1-gallon measuring cup. We then collected 12 ounces of purified water in a separate cup, recording the volume of wastewater produced during this time.

The G3 produced 8 ounces of wastewater for the 12 gallons of water purified, which equates to approximately 1:0.6 (meaning that for every 1 ounce of purified water, about 0.6 ounces go to drain).

Many of the RO systems we tested performed less efficiently than claimed, which likely comes down to our specific test conditions. Our water temperature is lower than the typical recommended range for efficient RO performance (58.3°F, with the recommended range being around 77°F). This can slow permeate flow and increase drain flow, significantly reducing recovery rate. 

We then conducted a second test, this time measuring the volume of wastewater produced when dispensing 64 ounces of purified water. In this test, 29 ounces of wastewater were recorded, equal to a pure-to-wastewater ratio of approximately 1:0.45. That means for every 1 ounce of water purified, 0.45 ounces of water goes to drain.

You can see that this result is better than with our smaller-volume test. Most likely, this is because of backpressure on the RO membrane. 

When the system is switched on after being unused for a period, it has water on both sides of the membrane, causing the pressures to gradually equalize across it. The membrane won’t immediately operate at full differential pressure when you turn it back on, so initially, more water goes to drain relative to the purified product. 

What does that mean?

Essentially, when we collected just 12 ounces of purified water, this captured mostly the less efficient period. But the system had time to stabilize and operate at its slightly better recovery rate when we were taking the larger 64-ounce draw.

📐 Design

Score: 9.70

In the design category, we ranked the Waterdrop G3 P800 based on its component quality and whether it had any certifications for its design materials. 

Out of the box, our unit came with:

• The system housing and three initial filters
• A smart RO faucet
• A UV sterilizer
• A feed water adapter
• Three sets of flexible tubing
• A power adapter
• Drain saddle
• Five lock clips
• Teflon tape

As far as design is concerned, we were pleased with the features of this under-sink RO system.

Waterdrop is known for its smart systems, and the G3 P800 has a few useful features that made it easier for us to use the unit as intended. There are TDS meters on the smart faucet and the unit body, which we could use to check on the performance of the filters, and a filter life tracker, so we didn’t have to make our own calendar reminders for filter changes.

Another unique perk of the unit is that it comes with a UV purifier (which boasts a 99.9% sterilization rate), so we had the reassurance of protection against pathogens. The only thing we felt it was missing was a built-in remineralization filter – we could buy one from Waterdrop, but it needs to be installed separately and costs an extra $30.

Component Quality

Score: 9.50

The G3 P800 is a plastic-based model. We reached out to Waterdrop to learn more about the types of plastics that are used in the system design, and we were told that the plastic components that the water comes into contact with are made from polypropylene (PP) and polypropylene (PE). These plastics are commonly used in making consumer goods because they’re rigid and relatively cheap, as well as being considered “relatively stable” and safer for food and drink. 

That said, as with most plastics we’ve come across, there’s still concern about leaching additives (although heat, duration, and acidity increase leaching, and none of these are likely in a reverse osmosis system).

The unit comes with a lead-free brushed nickel faucet. The idea of having a dedicated faucet is that you can ensure no materials will leach into the water after it has been purified. Plus, you need to retain your own existing kitchen faucet for hot water (the RO system is for cold water only).

Certification

Score: 10.00

The Waterdrop G3 P800 ticked our boxes for materials safety certifications. Materials safety certifications were an included component of the unit’s NSF performance certifications. It also has an IAPMO certification to NSF Standard 372 for a lead-free design.

Filter Materials

There are three filters used in the Waterdrop G3 P800. The first is a carbon block and sediment pre-filter, followed by an activated carbon coconut filter, and then a semi-permeable RO membrane. 

Waterdrop doesn’t go into great detail about the exact materials used to make these filters, but our research tells us that activated carbon filters are generally made from natural materials, and RO membranes are thin film composite membranes made from cellulose acetates, polyamides, polyimides, and poly-sulfones.

We couldn’t find any evidence to suggest that these materials might be unsafe for water filtration, and there have been dozens of studies that support the safe and effective use of RO membranes and activated carbon filters for drinking water treatment.

The filter housings themselves are made of plastic, as is typical for most water filters. 

⚙️ Setup

Score: 7.00

We evaluated the complexity of installing the G3 P800, and how long the process took us. 

We found that installing the Waterdrop G3 P800 was much easier than installing a traditional under-sink RO system, and the unit took up less space (it measures just 5.67 inches across). 

In all, installing the system took us around 2 hoursfrom start to finish.

We installed it at our cold water pipe using the provided flexible tubing. Everything we needed for installing and setting up the system was included in our box, and the user manual has a detailed 8-step installation process, with diagrams included, which we found easy enough to follow.

Plus, we noted lots of little benefits with this system in particular, like an included pipe cutting tool and the feed line already connected to cold water shutoff valve. There was also 1/4″ tubing labeled for drain included in the box, and the tubing have markings that show how far they need to be inserted to be properly sealed. It’s small features like this that can make a real difference when it comes to simply understanding what can, for most folks, be a fairly complex install.

There’s a bit of extra work required to drill a hole in your countertop for the RO faucet, which you’ll have to do if you don’t already have a hole (such as for a soap dispenser). We don’t recommend replacing your existing faucet with the RO faucet because the system can only be used with cold water, so you still need an additional faucet for hot water.

We also had to connect the drain pipe to our drainage system, since we needed to be able to direct the wastewater somewhere.

We noted a total of 9 leak points at the fittings—that means 9 opportunities for the unit to leak at any point throughout its operation.

After finishing the install, we followed the instructions in the user manual to flush the unit. This initial flush took just 35 minutes; one of the shortest times of all the under-sink RO systems we tested.

Do we think the install is possible if you’re not confident with DIY?

Yes, but make sure to follow the instructions in the user manual carefully.

Noise

With the G3 up and running, we measured its noise levels to see how loud its internal water pump was when switched on. 

We used a phone app to measure sound decibels at 1 foot and 3 feet away. At 1 foot, the unit produced 46.4 decibels, and at 3 feet, it produced 43.6 decibels. For context, that’s about as loud as a fan oven.

🔧 Maintenance

Score: 10.00

When rating the Waterdrop G3 P800 in the Maintenance category, we evaluated its servicing requirements and the cost per gallon of the filters. 

Servicing Requirements

Score: 10.00

Our only regular maintenance task for the G3 P800 was to change the filters according to the filter replacement schedule.

Here’s the key maintenance information to be aware of:

• The CF filter needs changing every 6 months
• The CB filter lasts for 8-12 months
• The RO membrane lasts for two years
• The UV lamp doesn’t need changing at all – it lasts up to 50 years with little or no maintenance required

We didn’t have to remember to replace our filters because the G3 P800 has a built-in filter change reminder. This is just an indication based on gallon usage or time, whichever comes first. So if you use a lot of water, the filter will need replacing more frequently due to your faster gallon usage.

Changing the filters was quick and easy, and we didn’t have to shut off our water or power supply. We just had to twist out the old filter, insert the new filter in its place, and reset the filter life timer. 

Our only annoyance was having to flush the filters after changing them – the CF filter flushes automatically, but we had to turn on the RO faucet to flush the CB filter for 15 minutes, which was time-consuming and felt wasteful. The same must be done when replacing the RO filter, except you have to flush it with water for 30 minutes (we haven’t had to replace ours yet).

Costs

Score: 10.00

To determine the G3 P800’s long-term value for money, we calculated the cost per gallon of each of the filters in the unit, then combined them to get a total figure. 

The system’s cost per gallon including the remineralization filter is $0.11/ gallon, equating to a total annual cost of $124.75, and a 5-year ownership cost (including the cost of the upfront purchase) of $1,622.77. 

That means the G3 P800 has one of the lowest costs per gallon of all the filtration systems we’ve tested, even with multiple filters to replace. 

🏢 Company

Score: 8.80

Lastly, we graded the warranty, shipping, and returns offered by Waterdrop for the G3 P800. 

Warranty 

Score: 8.50

The Waterdrop G3 P800 is backed by a 1-year warranty, which covers any defects that occur during the warranty period (due to a quality issue and not misuse). The warranty entitles customers to free returns, repair services, or replacements, depending on the issue reported. 

You can view the warranty terms on page 18 of the user manual. 

Shipping 

Score: 9.5

Waterdrop offers free Economy Shipping for all its products, and provides delivery to most US states. Waterdrop currently doesn’t ship to Alaska, American Samoa, Hawaii, Guam, Marshall Islands, Micronesia, Northern Mariana Islands, Palau, Puerto Rico, or the U.S. Virgin Islands.

For faster delivery, you can upgrade to Standard Shipping (at no extra cost if your order is over $200) or Express Shipping (at a cost of $12.99). 

View Waterdrop’s shipping policy here. 

Returns

Score: 8.00

The G3 P800 is backed by Waterdrop’s 30-day return policy. The product should be disassembled and returned in its original packaging, and you’ll need to cover the return shipping fee.

Waterdrop also allows for returns beyond the 30-day returns window, but there’s a 10% restocking fee as well as the return shipping fee. 

Here’s Waterdrop’s returns policy for more information.

💰 Value For Money

Overall, we think the G3 offers exceptional value for money when we consider everything it offers. It’s performance certified and had one of the fastest filtration rates of any RO system in our testing. It did a great job at reducing most contaminants in our water, and the remineralization filter noticeably improved pH and alkalinity.

That said, we weren’t impressed by the introduction of nitrite in our water purified by the with-remineralization configuration. Plus, boron was barely reduced at all, and it’s a bit annoying that the remineralization filter needs to be installed separately rather than being built into the system.

If you’re looking for an RO system with a great flow rate, extensive certifications, and impressive contaminant reduction abilities, the G3 is worth considering. In fact, it’s currently the highest-scoring tankless under-sink reverse osmosis unit we’ve tested so far, featuring in our roundup of top recommended reverse osmosis filters. 

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