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Waterdrop G3 P800 Reverse Osmosis System Review

Waterdrop G3 P800 Reverse Osmosis System

The Waterdrop G3 P800 is an evolutionary upgrade to the very popular Waterdrop G3 (P400) and offers an array of features that are not available in any other tankless under-sink RO systems.  

These unique features of this system include:

  • 800 gallon per day (GPD) throughput
  • 3:1 filtered water to wastewater ratio
  • LED UV sterilizer stage
  • Integrated TDS meter and smart features

The seven stages of filtration through three separate filters include a sediment pre-filter, a carbon post-filter, and a 0.0001μm RO membrane that effectively removes 99% of all harmful substances.

When you consider that the Waterdrop G3 P800 takes up less room, creates more clean water, and provides better feedback than any other system on the market, it should be at the top of your list!

Waterdrop G3 P800 Water Filter
Waterdrop G3 P800

Use code RS199 for $199 OFF the Waterdrop G3 P800!

High Efficiency

Extremely high throughput and efficiency are two of the most exciting features of the Waterdrop G3 P800.

This system can produce a whopping 800 gallons of filtered water per day (GPD), which is enough for a very busy household and even small businesses that requires large amounts of filtered water.

In addition, it does this with an exceptional 3:1 waste water ratio, meaning it creates only 1 gallon of waste water for every 3 gallons of pure water.

Wastewater is a necessary byproduct because a reverse osmosis machine uses pre-filtered water to clean the filter membranes of collected impurities. Most systems that are considered efficient get a 1:1 or 2:1 ratio and traditional RO systems can flip this ratio and only produce 1 gallon for every 3 gallons wasted.

In our tests, it only takes about 6 seconds to fill a cup of water with the G3 P800.

System Design

Complete filtration

The Waterdrop RO G3 P800 has eight stages of filtration.  They include:

  • Three stages in the pre-filter including a scale inhibitor (to treat hard water)
  • Three stages and seven layers in the RO filter, which is nearly 3x larger than most other brand’s RO filters
  • One stage in the final carbon filter
  • 99.9% effective Ultraviolet (UV) sterilizer

Combined, these filters remove nearly all of the possible dangerous chemicals from your water, including chlorine, phosphates, nitrates, arsenic, chromium, and PFAS “forever chemicals.”

Ultraviolet (UV) Sterilizer

Waterdrop G3 P800 UV filter
The UV filter gets power from the P3 G800 and sterilizes water after it has passed through the other filters

After the seven filtration stages, the UV filter effectively removes any microorganisms that may still be present in the water.

This is currently the only tankless water filtration system that comes with an integrated UV filtration stage.

The UV filter is actually external to the system chassis but connects to the main unit using a dedicated power cord and only operates when the system processes water.

Instead of using a traditional mercury-vapor UV lamp, the Waterdrop uses an advanced LED chip that effectively destroys 99.9% of microorganisms, bacteria, and viruses. According to Waterdrop, the LED light should last 50 years, which is much longer than other lamp types!

Waterdrop installs a leak detector into the case by default, and most other systems don’t include one.  If there ever was a leak, the detector will alert you before it can become an issue.

Smart features

Waterdrop G3 P800 smart indicators

Like it’s predecessor (G3 P400), the G3 P800 has a lot of “smart” features that give you feedback on the status of your system and quality of your water.

The system includes a built-in TDS (total dissolved solids) meter to report the quality of the filtered water whenever the system is working. To obtain this data using any other system, you’d need a separate TDS meter to manually test water from the filtered faucet.

An LCD screen on the RO faucet includes a filter life indicator, TDS indicator, and error alerting so that you always know the full status of your system at a glance.

In addition, the system chassis has LEDs that report the same information for each filter module and the system beeps whenever a filter is in the “red” (replace) state.

Small size and easy install

Waterdrop G3 P800 hands-on unboxing

Because it is tankless, the Waterdrop G3 P800 system occupies roughly 50% less space than traditional RO models. If you don’t want a bulky RO drinking water system and a tank to take up valuable space under the sink, this will be a great option for you.

The overall dimensions are 18.11″ x 5.67″ x 17.72″.

The slim (just 5.7″ wide) case is designed to allow for easy front access of all internal filters and all of the necessary plumbing connections are easy to work with in the back.

Simple Maintenance

Filter replacements are a breeze…

The three filter modules slide into the system case’s front and are easily accessible.

When changing the filters, there is no need to turn off the water supply or use any tools – simply twist and pull out the old filter, push in the new one, and twist it to secure it. See the instruction manual for full details.

It only takes a few seconds to replace each filter!

Filters do need to be replaced periodically to maintain water filtration effectiveness and efficiency (see below for links to the replacement filters):

  • The pre-sediment filter should be replaced once every 6 months
  • The carbon post filter should be replaced once every year
  • The reverse osmosis membrane should be replaced only once every two years

Keep in mind that this system does require power to operate, so be sure you have a standard 110V-240V outlet available at the installation location.

Easy Installation

Waterdrop G3 P800 installation diagram

The Waterdrop G3 P800 undersink system is designed to be installed by anyone with rudimentary DIY skills.  A plumber is not needed for installation.

The only possible challenge to consider when installing a filtered water faucet is drilling a hole in the sink or countertop. If a hand sprayer, soap dispenser, or blank cover is already available for the faucet, drilling a hole may not be necessary.

While this is a very comprehensive package, check out our list of reverse osmosis system accessories for some extra things to think about while purchasing your new home reverse osmosis system.

The owner’s manual covers how to install the system, and Waterdrop recommends checking out their YouTube installation videos.

Waterdrop G3 P800 Pros

  • Super high 800 gallons of filtered water output per day
  • Tankless design is easier to install and maintain
  • Easy filter design – you can’t mess up the filter installation
  • The most advanced smart feedback systems let you know the status of filters and your water
  • Integrated pump increases efficiency, decreases waste, and saves money on water

Use code RS199 for $199 OFF the Waterdrop G3 P800!

Waterdrop G3 P800 Cons

  • It costs more than many competing products
  • Flow from faucet is good for a tankless system but not as fast as a traditional system with a storage tank
  • Tankless systems don’t provide good water pressure to refrigerators and ice makers.
  • An alkaline remineralization filter is not included but is available from Waterdrop as an add-on (see below)

Check out our reviews of the top reverse osmosis systems to compare the Waterdrop G3 P800 with the competition.


The Waterdrop G3 P800 is currently one of the smartest and most advanced undersink water filters.

While the price is a bit steep, it offers some of the most high-tech features we’ve seen. It frees up space under the sink and makes installation and maintenance a snap.

We highly recommend this system because:

  • Has EXTREMELY high daily output
  • Wastes very little water
  • Includes a UV filter, real-time TDS meter, and leak detector
  • Smart faucet shows the full status of the system
  • Filters are long-lasting and reasonably priced
  • This a compact system that is super easy to install and maintain

Use code RS199 for $199 OFF the Waterdrop G3 P800!

You may also be interested in:

Our recommended accessories for this or any other RO water system for home use will help you customize your installation!

Waterdrop G3 P800 RO Replacement filters

You can check back here to order additional filters if necessary. It might be a good idea to get a pre-sediment filter now so that you’ll be ready in six months.

When the Waterdrop G3 P800 system’s filter is approaching its end of life, a yellow light will appear on both the system’s front panel and the faucet. That is when you should come back to order a new filter.

About two weeks after the yellow light comes on, the light for that filter and on the faucet will turn red, and then it is time to install the new filter.

  • The pre-sediment (CF) filter should be replaced once every 6 months
  • The carbon post (CB) filter should be replaced once every year
  • The reverse osmosis membrane (RO) should be replaced only once every two years
    • Waterdrop G3 P800 RO filter (WD-G3P800-N2RO) – check Waterdrop for the current status

Waterdrop MNR Filter

Add remineralization to ANY RO System!

Waterdrop filter MNR remineralization stage

Some of our most popular recommended RO drinking water systems come with a remineralization stage that people really like. However, many RO systems do not come with this additional stage by default.

Remineralization restores many of the natural “spring water” minerals that are removed by the RO filtration process to previously-filtered reverse osmosis water.

The Waterdrop MNR filter adds 18 natural materials including calcium, magnesium, sodium, potassium back to your filtered water and can be installed with ANY water filtration system (not just those from the Waterdrop brand).

Mineral water has been linked in studies to reduce chronic illnesses, slow down the aging process, and improve digestion and immunity.