Waterdrop D6 600 GPD Tankless Under-Sink Reverse Osmosis System: specs

The Waterdrop D6 is a tankless reverse osmosis (RO) system that sits under the kitchen sink and supplies filtered drinking water through its own faucet. It is rated at 600 gallons per day and has a display on the faucet. This page explains what the main specs mean and what to confirm before installing one.

How reverse osmosis works

An RO system pushes water through a very fine membrane that lets water molecules pass while holding back most dissolved solids. Waterdrop says the D6's membrane has a filtration accuracy of 0.0001 μm. RO systems typically also use carbon and sediment stages before and after the membrane. They need a drain connection, because the rejected water carries away what the membrane held back.

Six-stage composite filtration

Waterdrop describes a 6-stage system. It lists reductions of TDS (total dissolved solids), chlorine, PFAS, PFOS, PFOA, lead and microplastics, among others. These are the brand's statements; if a particular result matters to you, look at the certifications and test data published for the model. The activated carbon block is made from coconut shells, and Waterdrop asks buyers to check for any allergy to it.

What 600 GPD and a 2:1 ratio mean

GPD is gallons per day, the flow the membrane can produce under rated conditions. Waterdrop says the internal pump and larger filter surface let you fill a cup in about eight seconds. The 2:1 pure-to-drain ratio means that for every two cups of filtered water, about one cup goes to the drain. Older tank-style systems generally waste more. Waterdrop suggests the drain water could be used for mopping or washing a car.

Tankless design

Without a storage tank, the D6 is compact. Waterdrop says it saves 70% of under-sink space compared with a traditional system, and that it avoids the recontamination possible when water sits in a tank. The listing gives the size as 16.0 x 6.0 x 12.0 inches (about 41 x 15 x 30 cm) and 22.2 lb.

The smart faucet

The faucet has a screen showing the live TDS reading and the remaining filter life. Waterdrop says it is waterproof. A filter-life indicator on the control panel does the same job. A TDS meter gives a general reading of dissolved solids, not a full water analysis.

Installation and filter changes

Waterdrop says a DIY installation can be done in about 30 minutes. An electrical outlet is required, because the system has a pump. Filters use a push-in design that Waterdrop says can be swapped in two seconds, with no tools and no need to move the unit.

Who it suits

It suits households that want filtered drinking and cooking water from a dedicated faucet, and have limited cabinet space. It also suits people comfortable with basic plumbing, or who can hire someone.

What to check before you buy

• Space: measure your under-sink cabinet, including pipes and a garbage disposal.
• Power: an outlet must be near the sink.
• Plumbing: you need a cold-water supply line and a drain connection; follow local plumbing codes and the manual.
• Faucet hole: confirm there is a spot on the sink or counter for the extra faucet.
• Water pressure: check the manual's supply pressure range.
• Upkeep: find out how often each filter needs replacing and where replacements come from.
• Allergies: check the carbon material if that is a concern.

The short version

• A tankless under-sink RO system, model C-WD-D6-B, from Waterdrop.
• 6-stage filtration, rated at 600 GPD with a 2:1 pure-to-drain ratio.
• Smart faucet displays TDS and filter life.
• Needs an electrical outlet; tool-free push-in filter changes.
• Measures 16.0 x 6.0 x 12.0 inches and weighs 22.2 lb.

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