Waterdrop WD-TST-B Under-Sink Ultrafiltration System: specs and fit

The Waterdrop WD-TST-B (TST-UF) is an under-sink water filtration system with its own drinking-water faucet. It uses a 0.01 micron ultrafiltration membrane and keeps a tap's natural minerals in the water. Here is what its specs mean and what to check before fitting one.

What ultrafiltration means

Ultrafiltration (UF) passes water through a membrane with very small pores. Waterdrop gives the pore size as 0.01 microns and says the system removes 99.99% of contaminants larger than that. UF works by size, so it is different from reverse osmosis, which also reduces dissolved salts. A key point in the listing: this filter does not reduce TDS (total dissolved solids). Waterdrop says it keeps minerals such as potassium, calcium, sodium and magnesium.

Six layers of filtration

The listing describes six layers of filter material, including the UF membrane and coconut-shell carbon. Waterdrop says the system targets things such as chlorine, heavy metals and odours. Check the manufacturer's certifications and test data for what it is actually rated for. Because the carbon is made from coconut shell, Waterdrop advises that anyone with a coconut allergy should avoid it.

Flow rate

Flow is up to 1.59 GPM, and Waterdrop says an 8-ounce cup fills in about 2.3 seconds. Under-sink filters with a storage-free design generally deliver water straight from the tap rather than waiting for a tank to refill, so flow stays steady while you fill a pot or a kettle.

Filter life and three-stage cartridges

The set includes three filters. Waterdrop gives their life as:

• PP filter: 6 to 8 months
• UF filter: about a year
• CT (carbon) filter: 12 to 24 months

Actual life depends on your water quality and how much you use. The brand says the design avoids replacing plastic housings each time, which it describes as reducing waste.

Installation and placement

The system connects to a 3/8-inch or 1/2-inch water line. Waterdrop says there are installation videos and instructions, and customer service for questions. It can be placed on the floor or hung on the wall, and the listing says it can also be fitted to a faucet if space is tight. If you are not comfortable with plumbing, a plumber can do it, and local plumbing codes apply.

The dedicated faucet

A lead-free brushed stainless steel faucet is supplied. A separate tap lets you keep the main tap for washing and use the filtered tap for drinking and cooking. It does mean a hole in the sink or countertop, or an existing spare hole, so check before you start.

Materials and size

The housing is 304 stainless steel with a thick sealing ring to keep leaks at bay. The unit measures about 13 x 4.9 x 14.5 inches, so measure your cabinet, including pipes and any garbage disposal.

Who it suits

It suits households that want filtered water at the kitchen without losing minerals, or that want a refill-free setup for cooking and drinks. It isn't for anyone seeking to reduce TDS.

What to check before you buy

• Space: measure the cabinet, allowing room to change filters.
• Pipe size: confirm your supply line is 3/8 or 1/2 inch.
• Sink hole: check for a spare hole or whether you can drill one.
• Water supply: if you have a private well or concerns about water safety, get it tested and follow local advice.
• Replacement filters: note the types and ordering for the future.
• Coconut allergy: the carbon is made from coconut shell.

The short version

• Under-sink UF system with a 0.01 micron membrane and three filters.
• Keeps minerals; does not reduce TDS.
• Up to 1.59 GPM, with a lead-free stainless faucet.
• Fits 3/8 or 1/2 inch lines; floor or wall placement.
• Filter lives given: PP 6-8 months, UF 1 year, CT 12-24 months.

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