Water filter · ro
Waterdrop G3P800 Tankless RO
A tankless 800 GPD reverse-osmosis system certified to NSF/ANSI 42, 53, 58 and 372 with an efficient pure-to-drain ratio.
Flags
- · Marketed for PFAS removal but not certified to P473 (or 53+401).
Flags indicate missing certifications or data gaps under our rubric, not a confirmed finding that a product fails to perform.
Total cost of ownership
- Cost / gallon
- $0.123
- ~Annual filters
- $135/yr
- RO waste
- 0.33:1
Certifications
- NSF/ANSI 42, 53, 58, 372chlorine, lead, fluoride, cadmium, chromium-6, selenium, TDS
Overview
The Waterdrop G3P800 Tankless RO is a ro water filter. It is third-party certified (IAPMO) to reduce chlorine taste and odor, total dissolved solids (TDS), lead, fluoride, cadmium, chromium-6, selenium. It is also marketed for PFOA, PFOS, arsenic, nitrate, mercury, for which we found no accredited third-party certification (so we award no certification credit; this is not a finding that it fails to reduce them). Running cost works out to about $0.123 per gallon.
By the numbers
- Certified to reduce
- chlorine taste and odor, total dissolved solids (TDS), lead, fluoride, cadmium, chromium-6, selenium
- Marketed, no certification found
- PFOA, PFOS, arsenic, nitrate, mercury
- Format
- ro
- Cartridge life
- 2,200 gallons
- Cost per gallon
- $0.123
- Annual filter cost (~1,100 gal)
- $135/yr
- RO wastewater ratio
- 0.33:1 (reject:produced)
- Install
- under-sink, DIY quick-connect with dedicated faucet
- Certifications
- IAPMO NSF/ANSI 42, 53, 58, 372
Strengths
- + Certification Independence: 8.0/10
- + Practical Fit: 10.0/10
Watch-outs
- - Verified Contaminant Reduction: 4.0/10
- - Total Cost of Ownership: 1.0/10
- - Marketed for PFAS removal but not certified to P473 (or 53+401).
Who it is for
- · Homes with lead service lines or older plumbing (certified for lead)
- · Households needing broad dissolved-contaminant reduction (TDS, etc.)
Who should skip it
- · Anyone buying specifically for PFOA - it is marketed for it but not certified
What to know before buying
- · This is a tankless reverse osmosis system rated at 800 GPD with a roughly 3:1 pure-to-drain ratio.
- · It uses three replacement filters on staggered schedules: CF pre-filter every 6 months / 550 gallons, CB carbon filter yearly / 1,100 gallons, and the RO membrane every 2 years / 2,900 gallons.
- · It requires electricity to run the pump, so it stops dispensing during a power outage.
How it scored
Verified Contaminant Reduction
4.0/10 · 35%Held NSF/WQA/IAPMO certifications for the contaminants that matter. A claim is not a certification.
Capped at 4.0 (raw 5.0): Marketed for PFAS removal but not certified to P473 (or 53+401).
- +3NSF/ANSI 53 certified for lead ANSF/53 lead - Independently certified to reduce lead under NSF/ANSI 53.
- +1NSF/ANSI 42 certified for chlorine ANSF/42 chlorine - Certified to reduce chlorine taste and odor.
- +1NSF/ANSI 58 RO certified ANSF/58 - Reverse-osmosis system certified under NSF/ANSI 58.
Total Cost of Ownership
1.0/10 · 25%Computed cost per gallon vs the format-class median. The number nobody surfaces.
- 0Cost per gallon vs class median A$0.123/gal (above class median (expensive to run)) - Computed cost per gallon scored against the format-class median.
- +1Efficient RO wastewater ratio B0.33:1 reject:produce - Rejects 2 gallons or fewer per gallon produced.
Certification Independence
8.0/10 · 15%Certified on the official database vs self-claimed 'tested to' marketing.
- +5Certifications verifiable on official database A1 listings - Certifications are listed on the official NSF/WQA/IAPMO database, not just a logo.
- +3Per-contaminant reduction disclosed Bperformance data sheet - Publishes percent reduction per contaminant at rated capacity.
- ·Marketing exceeds certified scope Aclaims beyond certified scope - Marketing emphasizes contaminants the certifications do not cover.
Capacity & Flow Fit
7.0/10 · 15%Cartridge life and flow appropriate to the format.
- +3Cartridge life fits the format B2200 gal (norm 300) - Rated cartridge life is appropriate for this filter format.
- +2Sediment pre-filter present Bsediment pre-filter - Includes a sediment pre-filter for well or hard-water sources.
- +2Honestly rated filter life Bgallon rating matches typical use - Months claim matches the gallon rating at typical use.
Practical Fit
10.0/10 · 10%Install, footprint, and source-water readiness.
- +5Install type disclosed Cunder-sink, DIY quick-connect with dedicated faucet - Install method and difficulty are disclosed up front.
- +3Well / hard-water ready Brated for well/hard water - Pre-filtered or rated for well and hard-water sources when marketed for them.
- +2Predictable replacement schedule Chonest life rating - Replacement schedule is predictable from the honest gallon rating.
FAQ
- What are the replacement filters and intervals?
- The CF pre-filter is replaced every 6 months or 550 gallons, the CB carbon filter yearly or every 1,100 gallons, and the RO membrane every 2 years or 2,900 gallons, whichever comes first.
- Does it need power?
- Yes. It is a powered tankless under-sink unit, so it will not dispense filtered water during a power outage.
Related guides
This score is our opinion under our published rubric, not a statement of objective fact or a lab test of this product. We score what third-party certifications prove; absence of a certification means we found no verification, not that a product fails to perform. Last reviewed 2026-06-01. Scored under water-v1.0. Prices and certifications are re-verified on a cadence; see the methodology for how each rule fires.