Waterdrop G3P800 vs G3P600: Which Tankless RO Should You Buy?

Short answer: buy the G3P800 if you want faster flow, less water to the drain (3:1 vs 2:1) and a UV stage. Buy the G3P600 if you're a smaller household that mainly wants certified tankless RO and doesn't need the extras. Both list NSF/ANSI 58 certification, share the same filter schedule, and need an outlet under the sink.

Published October 1, 2026. All specs come from Waterdrop's product pages and comparison chart, and both links were checked and in stock on the day of publication. We haven't tested either unit ourselves, and we don't run a lab.

Spec comparison (from Waterdrop's chart)

G3P800

• Flow: 800 GPD
• Pure-to-drain: 3:1
• Stages: 10
• UV sterilizer: yes
• Filters: CF 6 months · CB 12 months · G3P800-RO 24 months
• Gallon ratings: 550 / 1,100 / 2,900
• Certification: NSF/ANSI 42, 53, 58 and 372 (IAPMO R&T)
• Warranty: 1 year
• Size: about 18.1 × 5.7 × 17.7 in; 36 lb

G3P600

• Flow: 600 GPD
• Pure-to-drain: 2:1
• Stages: 8
• UV sterilizer: no
• Filters: CF 6 months · CB 12 months · G3P600-RO 24 months
• Certification: NSF/ANSI 58 and 372 among others (IAPMO R&T), per Waterdrop's product page
• Warranty: 1 year
• Size: about 18.1 × 5.7 × 17.7 in; 32.4 lb

Neither model remineralizes. Waterdrop's chart marks both as having no alkaline/mineralization stage.

What the differences mean in practice

Flow (800 vs 600 GPD). Both are fast compared with tank systems. The difference shows up when you're filling a pot or several bottles back to back. Bigger households and heavy cooks will notice it more.

Drain ratio (3:1 vs 2:1). For every 3 gallons of purified water, the G3P800 sends about 1 to the drain. The G3P600 sends about 1 for every 2. If you're on a well with a septic system, or you care about water use, the G3P800 has the edge.

UV stage. The G3P800 includes a UV sterilizer at the end of its filter train. That's a polish for water that's already microbiologically safe, not a substitute for disinfecting a contaminated well. See RO for well water.

Running cost. Waterdrop's own chart listed an "average annual cost" of $159.97 (G3P800) and $144.97 (G3P600) on October 1, 2026. Those are the manufacturer's figures and will change with its prices. To work out your own number, see how often to change RO filters.

Which one to buy

Choose the G3P800 if:

• You have 4+ people or cook with filtered water every day
• You're on a well/septic system or want the least water to the drain
• You want the UV stage

Choose the G3P600 if:

• You're a household of 1 to 3 and mainly want certified RO drinking water
• You want the lower running cost on Waterdrop's own chart
• You don't need UV

Choose neither if: you rent or can't install under the sink. Look at countertop RO instead (G3P800 vs AquaTru). Or if you have no outlet under the sink, consider a tank system (see our best RO systems).

Frequently asked questions

What is the difference between the Waterdrop G3P800 and G3P600?

Per Waterdrop's comparison chart: the G3P800 is rated 800 GPD with a 3:1 pure-to-drain ratio, 10 stages and a UV sterilizer. The G3P600 is rated 600 GPD with a 2:1 ratio and 8 stages, and has no UV stage. Both share the same filter schedule, a 1-year warranty and an NSF/ANSI 58 certification.

Is the G3P800 worth the upgrade over the G3P600?

It is if you want the faster flow, less water to the drain, or the UV stage. If you are a smaller household and mainly want certified RO drinking water, the G3P600 covers that.

Do the G3P800 and G3P600 use the same filters?

They follow the same schedule (composite pre-filter every 6 months, carbon block every 12 months, RO membrane every 24 months), but Waterdrop lists model-specific RO cartridges (G3P800-RO and G3P600-RO). Buy the replacements that match your model.

Do both need electricity?

Yes. Both are tankless systems with an electric booster pump, so you need an outlet near the sink.

Related guides

• Premium tankless RO options
• The best tankless RO system (G3P600 focus)
• Waterdrop G3P800 vs AquaTru
• Waterdrop vs. Aquasana