Waterdrop TSB-ALK Under-Sink Water Filter: features, specs and who it suits

The Waterdrop TSB-ALK (model WD-TSB-ALK) is an under-sink water filter that sits in the cabinet below the kitchen sink and delivers filtered water through its own small faucet. It combines three cartridges into eight stages of filtration and adds an alkaline stage that Waterdrop says improves taste. It is aimed at households that want better-tasting drinking and cooking water without a countertop pitcher.

What the eight stages are for

Waterdrop describes the system as three filters giving eight stages of filtration. The brand says it is designed to reduce chlorine, taste and odour, fluorides, heavy metals, rust, sediment, sand and particles, and that this has been tested by a third-party lab. The listing also names PFAS, PFOA and PFOS among the substances it targets.

Multi-stage systems like this usually work in order. A sediment stage catches grit and rust flakes first, so they don't clog the later stages. Activated carbon then handles chlorine, taste and odour. Specialised media handle dissolved substances. Waterdrop says KDF material is used for heavy metals and an ion exchange resin for fluoride.

The alkaline stage

The last stage adds minerals, and Waterdrop lists calcium, magnesium, sodium and potassium. The brand says this gives the water a slightly alkaline character and a better taste. Waterdrop also notes that the system does not reduce TDS (total dissolved solids). Reverse osmosis systems do that, but this is a different type of filter. If you want to know exactly what a filter does and doesn't remove, look for the certification and test data the brand publishes for the specific model.

Cartridge life and storage

Waterdrop rates each of the three filters at up to 12 months. Real lifespan generally depends on how much water you use and how clean your supply is, so treat it as an upper figure. The brand's advice for time away is to put the cartridges in separate sealed plastic bags and keep them in the refrigerator (not the freezer) for up to 30 days.

Installation and the dedicated faucet

The filter uses a twist-and-lock design. Waterdrop says it can be set up in about three minutes and a filter swapped in about three seconds, without a plumber. The dedicated faucet means filtered water comes from a separate tap, so the filter does not process the water used for washing up. That usually extends cartridge life. Installing it typically means finding a spot in the sink or countertop for the extra faucet, so check that you have a free hole or can drill one where the manual allows.

Size and clogging

The unit measures 16.8 x 12.9 x 4.3 inches (about 43 x 33 x 11 cm) and weighs 1.5 lb (about 0.7 kg). Waterdrop says an upgraded filtration area gives 20 times more dirt adhesion, which should reduce clogging between changes.

Who it suits

It suits people who want a dedicated drinking-water tap in the kitchen, renters and owners who prefer a tool-light installation, and households that like the taste of mineral-enriched water.

What to check before you buy

• Cabinet space: measure the area under your sink, including pipes and any waste disposal unit.
• Faucet position: confirm there is room for the extra faucet on your sink or counter.
• Water supply: check the connection type and your supply pressure against the manual.
• What you need removed: check the brand's test data for the contaminants you care about, and remember that it does not reduce TDS.
• Replacements: look at how and where replacement cartridges are supplied for this model.
• What's in the box: confirm the fittings and faucet are included.

The short version

• An under-sink filter with three cartridges and eight stages of filtration, including an alkaline stage.
• Waterdrop rates each cartridge at up to 12 months.
• It has its own faucet and a twist-and-lock installation.
• It does not reduce TDS.
• It measures 16.8 x 12.9 x 4.3 inches and weighs 1.5 lb.

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