Waterdrop TSU WD-TSU-W Under-Sink Ultrafiltration System: specs

The Waterdrop TSU (WD-TSU-W) is a three-stage under-sink water filter that uses an ultrafiltration membrane. It connects to the cold water line and has its own faucet on the sink. Waterdrop positions it as an alternative to reverse osmosis (RO) for people who want filtered drinking water without a storage tank, a drain line or a power connection.

What ultrafiltration does

Ultrafiltration (UF) passes water through a membrane with extremely fine pores. Waterdrop quotes 0.01 microns, which is smaller than bacteria and many particles. The system also uses a carbon-based stage for taste and odour. The brand says it reduces more than 30 substances, including chlorine, PFAS and heavy metals, and improves taste and smell. Check the performance data sheet and any third-party test reports for the exact contaminants and reduction levels.

UF versus reverse osmosis

RO pushes water through a much tighter membrane, which removes dissolved salts and creates a stream of wastewater. UF doesn't do this. Waterdrop notes clearly that the system does not lower TDS (total dissolved solids), so it will not soften hard water or remove dissolved minerals. The brand presents that as a feature, because essential minerals stay in the water. If your main concern is dissolved solids, UF is not the right tool.

Three stages and replacement timing

The three filters have different lifespans, according to Waterdrop:

• UF membrane: 24 months
• CT (carbon) filter: 12 months
• PP (sediment) filter: 6 months

A smart panel with four lights reminds you when to change filters. Actual life depends on your water quality and use, so follow the manual.

No tank, no power, no drain

The system is tankless. It needs no electricity, doesn't send water to a drain and Waterdrop says there is no pressure drop at the faucet. Because it needs no drain connection, it avoids the drilling that RO systems often require.

Size and installation

The listing gives the unit's dimensions as 4.68 inches wide, 13.97 inches high and 14.81 inches long, and says it fits cabinets even with a large food waste disposer. The installation kit is included and fits both 1/2-inch and 3/8-inch pipes. Waterdrop says the brushed nickel faucet is included. You will usually need to drill a hole in the sink or countertop if there isn't a spare one.

Materials certification

Waterdrop says the system is certified to IAPMO NSF/ANSI 372 for lead-free, food-grade and BPA-free construction. That standard covers the materials in contact with water rather than how well the filter removes contaminants.

Who it suits

It suits households that want better-tasting drinking water and lower levels of chlorine and the other listed substances, without the extra plumbing of an RO unit, and that are content to keep their water's mineral content.

What to check before you buy

• Your water report: compare what's in your supply with the contaminants the system lists.
• Cabinet space: measure the area under the sink.
• Pipe size: check that your supply line matches 1/2 or 3/8 inch.
• Sink hole: confirm you have a hole for the faucet or are prepared to drill.
• Filter replacements: note the replacement schedule and availability.
• Water pressure: check the operating pressure range in the manual.

The short version

• A tankless, three-stage under-sink filter with 0.01 micron ultrafiltration.
• No wastewater, no drain line and no electricity needed.
• Does not lower TDS; keeps minerals in the water.
• Filters last 24, 12 and 6 months; four-light panel reminds you.
• Includes a brushed nickel faucet and installation kit.

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