Verdict
All guidesResearchOpen dataMethodologyAboutContact
Head-to-head · Best Under-Sink Water Filters

Frizzlife MP99 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.

Verdict is reader-supported. As an Amazon Associate we earn from qualifying purchases. Some links on this page are affiliate links — if you click through and buy, we may earn a small commission at no extra cost to you. Our ratings are sourced from independent publications, not sponsors.
The short answer

Waterdrop G3P800 Tankless Reverse Osmosis System is the only one of the two with a published score (4.5); Frizzlife MP99 has none, so this is not a close call so much as an unmeasured one. 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.

Frizzlife MP99
Ranked #7 in Best Under-Sink Water Filters
Frizzlife MP99
Unrated2 sources$80as of Oct 10

The Frizzlife MP99 is a compact, affordable two-stage under-sink filter with a clever twist-change cartridge and a strong 1.4 GPM dedicated faucet. Tested to NSF/ANSI 42/53, its 0.5-micron media reduces lead, chlorine and 70-80 VOCs while keeping beneficial minerals, and an auto shut-off valve spares you from cutting the water supply at filter-change time. It's a tidy, low-cost choice for essential filtration with an easy maintenance routine.

Strengths
  • — Tested to NSF/ANSI 42/53 by IAPMO R&T
  • — Retains beneficial minerals while removing heavy metals
  • — Includes a dedicated brushed-nickel faucet with a strong 1.4 GPM flow
Watch-outs
  • — Requires a hole for the dedicated faucet
  • — Does not reduce fluoride or total dissolved solids
$80 · Buy at frizzlife.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 →

How they stack up

Frizzlife MP99

The Frizzlife MP99 delivers 1.4 GPM through a dedicated faucet, against the 0.75 GPM of the Waterdrop 15UA, which connects to the existing faucet and has a longer filter life. Its two-stage design sits between the single-stage Waterdrop and the three-stage Aquasana Claryum AQ-5300+ and Clearly Filtered 3-Stage Under the Sink. It does not reduce fluoride, which the Clearly Filtered does, and it costs far less than the Aquasana.

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

SpecFrizzlife MP99Waterdrop G3P800 Tankless Reverse Osmosis System
Filtration2-stage compound, 0.5 micron—
CertificationsNSF/ANSI 42/53 (IAPMO tested)NSF/ANSI 42, 53, 58 and 372
Contaminants ReducedLead, mercury, chlorine, 70-80 VOCs—
Flow Rate1.4 GPM @ 60 psi—
FaucetDedicated brushed nickel included—
MaintenanceTwist-change with auto shut-off—
Mineral RetentionYes—
Replacement FilterFZ-2 cartridge—
Type—Tankless reverse osmosis with UV sterilizer
Rated Output—800 gallons per day
Dimensions—18.12 x 5.67 x 17.72 in
Filters—Sediment/carbon (CF), carbon block (CB), RO membrane
Filter Life—6 months (CF), 12 months (CB), 24 months (RO)
Rated Pure-to-Drain Ratio—3:1
Warranty—1 year
← See the full ranking of best under-sink water filters