Our Verdict
Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD — 8.8/10. A fast, space-saving tankless RO system that is well worth considering for households that want high-capacity filtered drinking water and can accommodate the under-sink installation requirements.
Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD — 8.8/10
The Waterdrop system is a strong choice for households that want fast, high-capacity reverse osmosis drinking water without the cabinet space penalty of a traditional storage tank. For a shopping-focused companion to this review, see our Waterdrop G3P800 buying guide.
Disclosure: This review is published by an affiliate-supported home technology site. If you buy through our links, we may earn a commission at no extra cost to you.
Overview
The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD is a tankless under-sink reverse osmosis water filtration system designed to deliver filtered drinking water through a dedicated faucet. Its core appeal is simple: cleaner-tasting water, reduced reliance on bottled water, and a more compact installation than older RO systems that use a bulky pressurized storage tank.
With an 800 GPD production rating, the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) is built for households that use a lot of drinking and cooking water. It is especially well suited to families, frequent coffee or tea drinkers, home cooks, and anyone who dislikes the slow dispensing speed and cabinet clutter associated with many conventional under-sink RO systems.
The main tradeoff is that the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) is not the simplest or cheapest water filter category. It requires under-sink space, a dedicated faucet, a drain connection, and access to power. For buyers who are comfortable with that setup, its fast flow, compact body, and low-maintenance filter design make it one of the more convenient ways to upgrade tap water at the sink.
Key features
The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) avoids a separate storage tank, helping preserve cabinet space and reducing the chance of stale stored water.
The high rated production capacity is aimed at faster dispensing and better support for busy households than lower-output RO systems.
The system is designed to reduce dissolved solids and common tap-water contaminants such as lead, chlorine, fluoride, and other impurities that affect taste and water quality.
Because there is no storage tank, the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) fits more neatly under many kitchen sinks.
The 800 GPD rating helps the system deliver filtered water more quickly than many lower-capacity RO setups, making it more practical for filling bottles, kettles, and cooking pots.
The filter design is intended to make routine maintenance easier, with cartridge changes that do not require a complicated teardown.
Installation note: The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) is an under-sink RO system, so plan for a dedicated faucet hole, a cold-water connection, a drain saddle connection, and a nearby power outlet before buying.
| Feature | Value |
|---|---|
| Product name | Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) |
| Model number | G3P800 |
| Category | Water Treatment Systems |
| System type | Tankless under-sink reverse osmosis system |
| Rated production capacity | 800 GPD |
| Primary use | Filtered drinking and cooking water from a dedicated tap |
| Filtration focus | Designed to reduce contaminants including lead, chlorine, fluoride, and dissolved solids |
| Storage tank | No separate tank |
| Installation location | Under kitchen sink or similar cabinet space |
| Filter replacement style | Twist-and-lock cartridge replacement |
| Best for | Households wanting high-flow RO water with a compact under-sink footprint |
| Not ideal for | Renters or buyers who cannot modify plumbing, add a faucet, or provide power under the sink |
Pros & cons
Pros
- High 800 GPD capacity supports faster filtered-water dispensing.
- Tankless design saves meaningful under-sink cabinet space.
- Designed to reduce dissolved solids and common contaminants that affect taste.
- Good long-term alternative to buying bottled water.
- Twist-and-lock filters make maintenance more approachable.
- Well suited to families and high-use kitchens.
Cons
- Requires under-sink installation, a drain connection, and a dedicated faucet.
- Needs power, unlike basic non-electric water filters.
- Higher upfront cost than pitcher filters or simple carbon under-sink filters.
- Reverse osmosis systems produce drain water as part of the filtration process.
- May be more system than a very small household needs.
Performance
In everyday use, the biggest advantage of the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) is convenience. Traditional RO systems can produce excellent water, but many of them dispense slowly and rely on a storage tank that consumes much of the cabinet. The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) is designed to address both issues with a higher-capacity tankless format.
For taste, the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) should be a major upgrade over untreated municipal tap water, especially in homes where chlorine taste, mineral content, or general tap-water odor is noticeable. Reverse osmosis is particularly useful when the goal is not just improving flavor but also reducing dissolved solids that basic carbon filters do not meaningfully remove.
The 800 GPD rating matters most when filling larger containers. If you regularly fill coffee makers, tea kettles, sports bottles, pet bowls, or cooking pots, the faster flow makes the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) feel less like a specialty drinking-water dispenser and more like a practical daily-use faucet.
Maintenance is another strong point. The twist-and-lock cartridge format is easier to live with than older housings that require wrenches, messy canisters, and more careful resealing. You still need to follow the replacement schedule and flush the system after filter changes, but the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) is clearly aimed at buyers who want RO-level filtration without making filter maintenance a weekend project.
Installation is the area where expectations should be realistic. The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) is not as simple as placing a pitcher in the fridge or screwing a filter onto a faucet. If your sink already has an unused accessory hole, the dedicated faucet installation may be straightforward. If not, you may need to drill a hole or use an existing soap-dispenser opening. Homes with crowded plumbing or limited under-sink outlets may also need extra planning.
Value for money
The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) makes the most financial sense for households that currently buy a lot of bottled water or are dissatisfied with the taste of tap water. The upfront cost is higher than basic filtration options, but the value improves over time if it becomes the primary source of drinking and cooking water.
Compared with a simple Brita Standard 10-Cup Pitcher or other pitcher filters, the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD is more expensive and more involved to install, but it is also far more capable. Pitchers are useful for simple taste improvement, while reverse osmosis is the better fit for buyers focused on reducing dissolved solids and a wider range of contaminants. For the lower-cost route, read our Brita 10-cup pitcher review.
Compared with traditional under-sink RO systems with tanks, the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD offers a cleaner cabinet layout and faster water delivery. Tank-style alternatives such as the iSpring 6-Stage Under-Sink Reverse Osmosis System with Alkaline Remineralization and the Express Water 10-Stage Alkaline Reverse Osmosis Under-Sink Water Filter System may appeal to buyers who prefer multi-stage alkaline remineralization. For more detail, compare our iSpring buying guide and Express Water ROALK10DCG review.
The best buyer for the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) is someone who wants a long-term water-quality upgrade and is comfortable investing in a more permanent installation. The least ideal buyer is someone who rents, moves frequently, lacks a convenient power outlet, or only needs occasional filtered water.
Final verdict
The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD earns an 8.8/10 for combining high-capacity RO filtration, a compact tankless design, and user-friendly maintenance in a system that suits busy kitchens. It is not the cheapest or simplest way to filter water, but for households that want fast, clean-tasting reverse osmosis water straight from the sink, it is a compelling upgrade.
Is the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) good for a family?
Yes. The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) is a strong fit for families because its 800 GPD rating supports faster water production and more frequent use than many lower-capacity RO systems.
Does the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) need a storage tank?
No. The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) uses a tankless design, which helps save cabinet space and avoids storing filtered water in a separate pressure tank.
What contaminants is the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) designed to reduce?
The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) is designed to filter out contaminants including lead, chlorine, fluoride, and dissolved solids, helping improve both taste and overall drinking-water quality.
Is the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) easy to maintain?
For an under-sink RO system, yes. The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) uses twist-and-lock filter replacement, which is simpler than older-style filter housings. You still need to replace filters on schedule and follow flushing instructions after changes.
Who should not buy the Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800)?
The Waterdrop Tankless Under-Sink Reverse Osmosis System 800 GPD (G3P800) may not be the best fit for renters, very small households, or anyone who cannot install a dedicated faucet, connect to the drain line, or provide power under the sink.
