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Head-to-head · Best Under-Sink Water Filters

Cloud RO Under-Sink Reverse Osmosis System vs Waterdrop G3P800 Tankless Reverse Osmosis System

Which is the better buy? Side-by-side on rating, price, strengths, and watch-outs — with the published ratings we averaged to get there.

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The short answer

Waterdrop G3P800 Tankless Reverse Osmosis System comes out ahead by a narrow margin (4.5 vs 4.4). Waterdrop G3P800 Tankless Reverse Osmosis System is best for: city-water households that want fast, thoroughly purified drinking water on tap. Read the strengths below before deciding.

Cloud RO Under-Sink Reverse Osmosis System
Ranked #2 in Best Under-Sink Water Filters
Cloud RO Under-Sink Reverse Osmosis System
2 sourcesall derived

The Cloud RO is a battery-powered, app-connected under-sink reverse osmosis system with eight filtration stages, remineralisation, a 2.8-gallon tank and a rated 80 gallons per day. The Spruce named it its best smart system after a year of use, citing easy setup, useful app monitoring and alerts, and enough output for a large household; Good Housekeeping found it compact, quiet and noticeably better tasting than NYC tap water. Both flag the cost: Good Housekeeping puts the starting price at about $600 with $200 replacement filters, and The Spruce notes a 1:1 waste ratio. It suits households that want RO water with real-time monitoring; buyers on a budget or short of cabinet space should look elsewhere.

Strengths
  • — The Spruce found setup easy, with well-labelled lines and fittings
  • — App shows tap and filtered water quality and sends filter-change alerts
  • — Battery powered, so no outlet is needed under the sink
Watch-outs
  • — Costs more than many RO systems, and replacement filters cost about $200
  • — 1:1 waste ratio, more wasteful than The Spruce's top iSpring pick
  • — Included faucet feels a little flimsy, and flow sputters on first use each day
Buy at cloudwaterfilters.comFull review →
Waterdrop G3P800 Tankless Reverse Osmosis System
Higher ratedRanked #1 in Best Under-Sink Water Filters
Waterdrop G3P800 Tankless Reverse Osmosis System
1 source$759as of Oct 17

The Waterdrop G3P800 is a tankless under-sink reverse osmosis system rated at 800 gallons per day. It uses three filter cartridges and an inline UV sterilizer, and needs an electrical outlet. Water Filter Guru scored it 9.21/10 after lab testing: it removed every contaminant found above health guideline levels and measured 886.54 GPD. Bob Vila praised its quick, leak-free filter changes and its 3:1 rated pure-to-drain ratio, and Reviewed noticed a clear improvement in taste. It suits city-water households that want fast, thorough purification. Well-water users, and anyone wanting minerals left in or a simple install, should look elsewhere.

Strengths
  • — Water Filter Guru measured 886.54 GPD, above the 800 GPD rating
  • — Removed every contaminant found above health guideline levels in lab tests
  • — Wastes less water than most tankless RO systems Water Filter Guru tested
Watch-outs
  • — Installation is involved; Reviewed had to hire a plumber
  • — No built-in remineralization; the add-on filter is sold and fitted separately
  • — The unit makes an audible groan when dispensing water
$759 · Check Price on AmazonFull review →

Derived means the reviewer published no score, so one was inferred from their written verdict. Everything else is a number the publisher printed. How we rank.

How they stack up

Cloud RO Under-Sink Reverse Osmosis System

Unlike the Waterdrop G3P800 Tankless Reverse Osmosis System, the Cloud RO stores water in a 2.8-gallon tank and runs on a battery rather than mains power. Like the APEC Water ROES-PH75 Essence Alkaline system it adds minerals back after RO filtration, but it is priced from about $600 and adds app monitoring; the Aquasana Claryum AQ-5300+ is a non-RO filter for buyers who want to avoid a tank altogether.

Waterdrop G3P800 Tankless Reverse Osmosis System

Unlike the Aquasana Claryum AQ-5300+, which the page recommends for keeping minerals in, the G3P800's RO membrane removes nearly all of them unless an add-on remineralization filter is fitted. It also needs an under-sink power outlet and a drain connection. At $759 it is a heavier investment than the Waterdrop 15UA or Frizzlife MP99, both recommended on this page for budget buyers.

Specs side-by-side

SpecCloud RO Under-Sink Reverse Osmosis SystemWaterdrop G3P800 Tankless Reverse Osmosis System
TypeUnder-sink reverse osmosis with tankTankless reverse osmosis with UV sterilizer
Dimensions11 x 7 x 16 inches18.12 x 5.67 x 17.72 in
Daily Production Rate80 gpd—
Filtration Stages8—
Tank Capacity2.8 gallons—
PowerBattery—
Waste Ratio1:1—
Rated Output—800 gallons per day
Filters—Sediment/carbon (CF), carbon block (CB), RO membrane
Filter Life—6 months (CF), 12 months (CB), 24 months (RO)
Certifications—NSF/ANSI 42, 53, 58 and 372
Rated Pure-to-Drain Ratio—3:1
Warranty—1 year
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