Zooz ZSE42 Water Leak XS Sensor

Quick verdict

A tiny, cheap water leak sensor you can scatter under every water appliance in the house. Detects water and sends an instant Z-Wave alert to Home Assistant. Pair it with the ZAC36 valve actuator and you have automated leak detection and shutoff. The peace of mind is worth more than the sensor costs.

Standout: Tiny water leak sensor that fits anywhere pipes run. Pair with a Z-Wave valve actuator for automated shutoff.

Last checked: 2026-03-22

Compatibility snapshot

Why it stands out

• tiny form factor fits under water heaters, behind toilets, under sinks, anywhere leaks start
• instant Z-Wave alert when water is detected with no polling delay
• pairs well with the ZAC36 water valve for automated shutoff

Reasons to hesitate

• battery is not user-replaceable on the XS form factor, as the entire unit is the battery
• Z-Wave signal can be weak if placed in a basement far from the nearest repeater
• no built-in siren, so you need Home Assistant to trigger an alert

Best for

• under sinks, water heaters, washing machines, and anywhere pipes can leak
• pairing with the Zooz ZAC36 valve actuator for automatic water shutoff on leak detection

Avoid if

• you want a sensor with a replaceable battery, since the XS design is sealed
• you need a standalone alarm that works without a Z-Wave controller

Privacy and local-control notes

Battery-powered Z-Wave sensor. No cloud needed. Leak alerts stay local on your Z-Wave network.

Home Assistant support: supported · integration path: Z-Wave JS.

Buying reality check

Price notes: Cheap enough to put one under every sink and water appliance. Buy a handful.

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