Waterdrop G3P600 vs G3P800 vs iSpring RO500AK-BN: tankless reverse osmosis compared

The three systems side by side

Three years of filters bring the G3P600 to $973.91 before installation and power^{1, 2}. The G3P800 is rated at 800 GPD with a 3:1 pure-to-drain ratio, against 600 GPD and 2:1^{1, 7}.

NSF lists the iSpring under NSF/ANSI 58 for TDS reduction only, and it lists neither Waterdrop^{5, 10, 18}. The iSpring’s filters cost the most, about $170 a year, and iSpring doesn’t say what power it needs^{11, 13}. All three carry a one-year warranty^{1, 3, 11, 12}.

Prices are US list prices on each maker’s site, before tax, checked on October 13, 2026. Checkout-code and subscription prices aren’t used. The three-year cost adds three years of filters to the purchase price and leaves out installation, electricity and drain water. Where a cell says a figure isn’t stated, we didn’t find it on the maker’s pages.

Which one fits which need

All three need a water supply line and a drain under the sink. Only the iSpring has an NSF listing, and it covers TDS reduction alone^{5, 10, 18}. Beyond that, the choice comes down to price, speed, drain water and whether you want minerals added back.

If tankless flow isn’t a must, APEC’s ROES-50 is a tank system at $230.99¹⁵. Its filters run about $55 a year if you change the pre-filters yearly and the full set every two years^{16, 17}. Its rated output falls from 50 GPD at 60 psi to 30 GPD at 50 psi¹⁵.

• Fast tankless RO for the least money: Waterdrop G3P600. It lists at $539, and Waterdrop rates it at 600 GPD with a 2:1 pure-to-drain ratio^{1, 2}. Filters cost $144.97 a year, the lowest of the three¹. The catch: NSF lists no G3P600, and the PFAS and fluoride claims come without test data^{1, 5}. It needs an outlet, and Waterdrop doesn’t publish the power draw¹.
• Faster flow and less drain water: Waterdrop G3P800. Waterdrop rates it at 800 GPD and 3:1, so less water goes down the drain for each glass⁷. The box list adds a UV sterilizer⁷. The catch: it lists at $999, $460 more than the G3P600, for the same size and the same one-year warranty^{1, 2, 7, 8}. Its certification list also changes across the page: NSF/ANSI 53 is in the spec table but not the feature list⁷.
• Minerals added back: iSpring RO500AK-BN. The last of its three stages is a coconut-shell carbon filter with added minerals for pH and taste¹¹. It’s the only one of the three that NSF lists, under NSF/ANSI 58 for TDS reduction^{5, 10, 18}. It’s also the smallest, at 5.12 in wide and 25.0 lb¹¹. The catch: filters run about $170 a year, the page doesn’t say what power it needs, and an opened return loses 15%^11–13.

Is the G3P800 worth $460 more?

Waterdrop rates the G3P800 at 800 GPD against 600 GPD^{1, 7}. At the tap, Waterdrop says the G3P800 fills a 6 oz cup in 5 seconds⁷. The G3P600 fills an 8 oz cup in 8 seconds¹. Scaled to 8 oz, that’s about 6.7 seconds against 8.

The bigger change is drain water. At 2:1, the G3P600 sends 1 gallon to the drain for every 2 gallons you get¹. At 3:1, the G3P800 sends 1 gallon for every 3⁷. At 3 gallons a day, the pace the filter ratings work out to, that’s about 1.5 gallons down the drain against 1. Over a year, the G3P800 sends about 180 fewer gallons to the drain. What that saves depends on your local water rate.

Everything else is close to the same. Both measure 18.11 × 5.67 × 17.73 in and weigh 32.4 lb^{1, 7}. Both faucets show TDS and filter life, and both use the same G3-N1CF and G3-N3CB filters^{1, 7}. The membranes differ: $139.99 for the G3P800 against $109.99, so its filters run $15 a year more^{1, 7, 9}. Over three years, the G3P800 costs $505 more at list prices^{1, 2, 7, 8}.

What the certification claims cover

Waterdrop lists NSF/ANSI 42, 58 and 372 for both models^{1, 7}. NSF’s database had no G3P600, no G3P800 and no Waterdrop reverse osmosis system under NSF/ANSI 58^{4–6, 10}. That rules out an NSF listing, not certification by another body such as IAPMO R&T or WQA. A G3P600 product image is labeled as an IAPMO R&T certificate for NSF/ANSI 372². That standard covers lead in the parts, not what the filters remove.

Both Waterdrop pages claim PFAS and fluoride reduction^{1, 7}. Both also claim 99% reduction of PFOA and PFOS, on the G3P600 only in an image caption^{2, 7}. Neither page gives a test standard, lab or per-contaminant result^{1, 7}. The G3P800’s image captions mention SGS and CSA testing, but give no results⁸.

iSpring ties its NSF/ANSI 58 claim to TDS reduction and says it covers the whole system¹¹. NSF’s database confirms it: the RO500AK-BN is listed under NSF/ANSI 58, and its only reduction claim is TDS¹⁸. The up-to-98% lead figure and the claim of more than 1,000 contaminants are iSpring’s own¹¹. If you’re buying for lead, PFAS or fluoride, ask the maker for the certifier listing that names the model and that contaminant.

Filters, power and drain water

At one-time filter prices, the G3P600 comes to $539 + 3 × $144.97 = $973.91 over three years^{1, 2}. The G3P800 is $999 + 3 × $159.97 = $1,478.91^7–9. The iSpring is $692.99 + 3 × $170.00 = $1,202.99, using its $339.99 two-year filter pack^{11, 13}.

Waterdrop’s gallon ratings work out to about 3 gallons of filtered water a day^{1, 7}. If you drink and cook with more, you’ll change filters sooner. iSpring’s two-year pack means replacing the membrane at 24 months, the short end of its 24 to 36 month rating^{11, 13}. Its $132.99 one-year pack covers stages 1 and 3 but not the membrane¹⁴.

Neither maker publishes power draw, so electricity is unknown for all three^{1, 7, 11}. iSpring’s product page doesn’t say whether the RO500AK-BN needs an outlet at all¹¹. Drain water adds to your water bill at local rates, and none of these totals includes it.

Installation, warranty and returns

Each one needs a water supply line and a drain connection under the sink. Waterdrop includes the faucet, feed adapter, drain saddle and tubing, and says you can install it yourself in about 30 minutes^{1, 7}. Both Waterdrops also need an outlet under the sink^{1, 7}. iSpring calls installation DIY but doesn’t give the drain hardware, faucet-hole size or pressure limits¹¹.

Neither Waterdrop product page gives water limits^{1, 7}. Waterdrop’s extended-warranty terms call for city water at 14.5 to 87 psi and 41 to 100°F³. TDS must be under 750 ppm and hardness under 7 grains per gallon, and well water needs pre-filtration³. Check those against your water report before you buy either Waterdrop.

All three have a one-year warranty, and iSpring’s requires registration^{1, 7, 11, 12}. Waterdrop takes returns for 30 days with no restocking fee³. You must disassemble and repack the unit, and you pay return shipping unless it’s defective³. iSpring refunds an opened item within 30 days only if it’s unused, and keeps 15%¹². Neither policy says whether an installed system can come back^{3, 12}.

Sources

1. Waterdrop G3P600 Undersink Tankless Reverse Osmosis System - Black Faucet Waterdrop · manufacturer
2. G3P600 Black Faucet listing on Waterdrop's store (price, regular price, SKU, availability and photo descriptions) Waterdrop · manufacturer · data file
3. Service Policy (returns, warranty and price match) Waterdrop · manufacturer
4. NSF listings: drinking water treatment units, trade name Waterdrop NSF · certifier
5. NSF listings: drinking water treatment units, trade name G3P600 NSF · certifier
6. NSF listings: NSF/ANSI 58 reverse osmosis systems, trade name Waterdrop NSF · certifier
7. Waterdrop G3P800 Undersink Tankless Reverse Osmosis System - Black Faucet Waterdrop · manufacturer
8. G3P800 Black Faucet listing on Waterdrop's store (price, regular price, SKU, availability and photo captions) Waterdrop · manufacturer · data file
9. WD-G3P800-N2RO Filter for Waterdrop G3P800 Reverse Osmosis Systems | 800GPD Waterdrop · manufacturer
10. NSF listings: drinking water treatment units, trade name G3P800 NSF · certifier
11. iSpring RO500AK-BN NSF Certified Tankless Reverse Osmosis Water Filtration System iSpring · manufacturer
12. Refund policy (returns and warranty) iSpring · manufacturer
13. iSpring F7-RO500AK NSF/ANSI 58 Certified 2-Year Replacement Filter Pack for RO500AK Tankless Reverse Osmosis Water Filtration System iSpring · manufacturer
14. iSpring F3-RO500AK NSF/ANSI 58 Certified 1-Year Replacement Filter Pack for RO500 Series Tankless Reverse Osmosis Water Filtration System iSpring · manufacturer
15. ROES-50 - Essence 5-stage 50 GPD Reverse Osmosis Water System for Drinking Water, WQA Certified APEC Water Systems · manufacturer
16. APEC RO Replacement Filters Pre-filter Set for All ESSENCE Reverse Osmosis Systems (Stages 1-3) APEC Water Systems · manufacturer
17. APEC RO Replacement Filters Complete Filter Set for ESSENCE ROES-50 System (Stages 1-5) APEC Water Systems · manufacturer
18. NSF listings: drinking water treatment units, trade name RO500AK (iSpring RO500AK-BN and RO500AK-ORB, NSF/ANSI 58, TDS reduction) NSF · certifier