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.

Yes. It is a powered tankless under-sink unit, so it will not dispense filtered water during a power outage.

Water filter · ro

Waterdrop G3P800 Tankless RO

Name: Waterdrop G3P800 Tankless RO
Brand: Waterdrop

A tankless 800 GPD reverse-osmosis system IAPMO-certified to NSF/ANSI 42, 53, 58 and 372 for a broad contaminant list including lead, PFAS, arsenic, nitrate and fluoride.

6.6/ 10

Mixed

Composite (0-10), water-v1.0

Confidence: Verified

Bottom line

In our scoring the Waterdrop G3P800 Tankless RO earns 6.6/10, a mixed result, and it stands out on certification independence (10.0/10). On the data, it holds IAPMO certification to reduce chlorine taste and odor, total dissolved solids (TDS), lead. It works out to about $0.123 per gallon, a middling cost per gallon. Its weakest area in our scoring is total cost of ownership (1.0/10). Certification is not a substitute for a water test of your own supply.

Where to buy

Check the current price on Amazon

Affiliate link: we may earn a commission at no extra cost to you. It never changes a score - how we handle this.

Total cost of ownership

Checked 42 days ago

Cost / gallon: $0.123
~Annual filters: $135/yr
RO waste: 0.33:1

Which cartridge fits, and where to reorder it

Certifications

NSF/ANSI 42chlorine
NSF/ANSI 53 & 58lead, arsenic, nitrate, mercury, fluoride, chromium-6, cadmium, selenium, copper, barium, TDS, PFOA, PFOS
NSF/ANSI 372low-lead material

Filters only protect you on their swap schedule. Get an email reminder when this one is due - one note around swap time, nothing else.

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, arsenic, nitrate, mercury, copper, barium, PFOA, PFOS. 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, arsenic, nitrate, mercury, copper, barium, PFOA, PFOS
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; IAPMO NSF/ANSI 53 & 58; IAPMO NSF/ANSI 372

Strengths

+ Verified Contaminant Reduction: 8.0/10
+ Certification Independence: 10.0/10
+ Practical Fit: 10.0/10

Watch-outs

- Total Cost of Ownership: 1.0/10

Who it is for

· Homes with lead service lines or older plumbing (certified for lead)
· Anyone targeting PFAS (certified for PFOA/PFOS)
· Households needing broad dissolved-contaminant reduction (TDS, etc.)

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

8.0/10 · 35%

Held NSF/WQA/IAPMO certifications for the contaminants that matter. A claim is not a certification.

+3NSF/ANSI 53 certified for lead ANSF/53 lead - Independently certified to reduce lead under NSF/ANSI 53.
+3Certified for PFAS (NSF/ANSI 53 or 58) APFOA/PFOS certified - Independently certified to reduce PFOA/PFOS.
+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

10.0/10 · 15%

Certified on the official database vs self-claimed 'tested to' marketing.

+5Certifications verifiable on official database A3 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.
+2Marketing matches certified scope Aclaims within certified scope - Hero claims are within what the certifications actually 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

Is the Waterdrop G3P800 Tankless RO NSF certified, and does it remove lead or PFAS?: Per the public NSF/WQA/IAPMO databases it holds IAPMO certification to reduce chlorine taste and odor, total dissolved solids (TDS), lead, fluoride, and more. It is certified for lead. It is certified for PFAS (PFOA/PFOS).
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.

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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 2026-06-06. Scored under water-v1.0. Prices were last checked 42 days ago; the freshness chip above the cost panel shows the current state. See the methodology for how each rule fires.