Waterdrop countertop reverse osmosis: the K19-SFK, K19-H, C1S and A1

The countertop models at a glance

As read on October 14, 2026, Waterdrop's C1S countertop RO was $259.00 and the K19-SFK $349.00; of the K19 models only the K19-H heats water, and the plain K19 is discontinued. Waterdrop's pages and IAPMO R&T's directory list the A1 and A2 dispensers only under NSF/ANSI 372, a standard for lead-free materials, so the PFAS, fluoride and lead claims on the A1 page are Waterdrop's own test claims.

A countertop unit sits on the counter and plugs in; Waterdrop says the K19-SFK needs no installation or drilling. The K19-H, $379.00, adds hot water, and the A1, $649.00, and the A2, $499.00, are hot and cold dispensers.

• C1S: $259.00, 75 GPD, 3:1.
• K19-SFK: $349.00, 75 GPD, 3:1, 170 oz tank.
• K19-H: $379.00, heats water.
• A1: $649.00, 100 GPD, hot and cold.

The C1S, K19-SFK, K19-H and A1 side by side

All four are fill-and-dispense units: you fill the water tank by hand, and each needs power. Waterdrop prints a 3:1 pure-to-drain ratio for the C1S, K19-SFK and K19-H and 2:1 for the A1, and rates the first three at 75 GPD and the A1 at 100 GPD.

The C1S measures 11.7 x 8.3 x 13.7 inches and has a detachable tank that Waterdrop calls fridge-friendly; the K19-SFK holds 170 oz. The A2 comes with a 40 oz pitcher and lists water temperatures of 59℉ to 203℉. For renters, the apartment guide sets these beside AquaTru's countertop units and pitchers.

Certification lines, model by model

The K19-SFK spec line says NSF/ANSI 58, and IAPMO R&T's directory lists the WD-K19-SFK-US under NSF/ANSI 58 with one reduction claim, TDS. Waterdrop's own pages disagree on the K19-H: its spec line says NSF/ANSI 58, its certification block NSF/ANSI 372, and its help-center table marks neither; the directory lists the WD-K19-H-US under NSF/ANSI 58 and in its lead-free certificate.

The C1S spec block prints no certification, Waterdrop's NSF page lists it under NSF/ANSI 372 only, and the directory lists the WD-C1S-US in its lead-free certificate. The A1 and A2 are listed under NSF/ANSI 372 only.

NSF/ANSI 372 caps the lead content of the materials at 0.25% weighted average, per Waterdrop's NSF page; it is not a claim that the system reduces anything.

Filters, warranty and returns

Each model takes its own replacement filter. Waterdrop rates the K19-SFK's K19RF-FK and the C1S's C1RF at up to 12 months or 1,100 gallons; the A1 uses an A1-CF of up to 6 months or 550 gallons and an A1-RO of up to 12 months or 1,100 gallons.

Each of these product pages shows a 1-year warranty badge. Waterdrop's service policy allows returns within 30 days of receipt for orders in the continental United States; you pay return shipping unless the return is for a quality issue, and items not returned in like-new condition carry a 10% restocking fee. See Waterdrop return policy.