How we chose these water leak sensors
We started with a simple test: does the sensor tell you about a leak fast enough to matter, and will it keep working unattended for a year or more? That meant a genuine wireless protocol Home Assistant can read, a long battery life (or mains power), and a waterproof or drip-proof body. We then looked at how each one behaves when the wet contacts are on a cable, because a probe that can lie flat under a boiler or run along a skirting board is far more useful than a puck that only detects water directly beneath it. Prices are UK list or single-retailer figures seen in September 2026 and move often, so treat them as bands.
In Home Assistant, every sensor here ends up as a binary sensor with the moisture device class, which the binary sensor documentation defines as "on" meaning wet and "off" meaning dry. That means one automation can handle any brand, and you can mix them freely.
The best smart water leak sensors for UK homes
1. Aqara Water Leak Sensor T1 — best overall
Who it's for: anyone building a Zigbee network who wants the cheapest reliable sensor to scatter around the house. Aqara lists the T1 as a Zigbee 3.0 device with an IP67 dust and water rating, a CR2032 battery good for roughly two years and a 0.5 mm water-level alarm threshold, so it trips on a thin film of water rather than a puddle. It is about 50 mm across and 15 mm thick, which is small enough to slide under a dishwasher.
The catch: Aqara's own app needs an Aqara hub, and the T1 has no external probe, so it only detects water at the point where it sits. If you run Home Assistant with a Zigbee coordinator, check that your integration lists this exact model before you buy in bulk; our guides to Zigbee2MQTT and ZHA explain how to check.
2. SONOFF SNZB-05P — best budget pick with a probe
Who it's for: Home Assistant owners who want a Zigbee sensor with a long battery life. SONOFF says the SNZB-05P uses a CR2477 cell rated for up to five years, is IP67 (submersible to 1 m for 30 minutes) and detects water as shallow as 0.5 mm with an elevated, gold-plated two-terminal probe. The version with a detection cable includes a 2 m extended lead, so you can hide the sensor body and run the probe under a bath panel or along the back of a boiler.
The catch: SONOFF sells versions with and without the cable, so check which one you are buying. Zigbee2MQTT's device page lists water leak, battery level and low-battery attributes, and the sensor works with a standard Zigbee coordinator such as those covered in our ZHA guide. CNX Software tested it with both eWelink and Home Assistant.
3. Shelly Flood Gen4 — best without a Zigbee hub
Who it's for: homes without a Zigbee coordinator, or anyone who needs to cover a long run of floor. The Gen4 packs Wi-Fi 6, Bluetooth 5, Zigbee and Matter into one unit, ships with a 2 m sensor cable that can be extended to 150 m in total, and has a built-in local buzzer with three alarm styles. It runs on four AA batteries for roughly two years and costs £33.99 at Shelly Store UK.
The catch: it is IP44, so treat it as splash-resistant rather than submersible, and the body is far larger than a puck (97 x 76 x 25 mm). Home Assistant's Shelly documentation does not name the Flood Gen4, so the safest route is Matter or Zigbee pairing, and battery-powered Shelly devices must be woken by pressing the button before setup.
4. Eve Water Guard — best for Apple Home
Who it's for: households already running HomePods or an Apple TV as a home hub. Eve's specification describes a mains-powered unit (100-240 V) with Bluetooth and Thread, a 2 m sensing cable extendable to 150 m in total, a red warning light and a 100 dB siren. Because it is plugged in, there is no battery to forget about, and it doubles as a Thread router.
The catch: mains power means it needs a socket near the risk, and Apple's hub is required for remote alerts. Home Assistant can pair HomeKit accessories through its HomeKit Device integration, but its documentation says a device paired to Apple Home must be removed from the Home app first, because HomeKit accessories only pair to one controller at once. If you want one setup for both, look at our Matter bridge guide.
5. Fibaro Flood Sensor — best for Z-Wave
Who it's for: anyone with a Z-Wave controller who wants a sensor that also watches for frozen pipes. The Fibaro FGFS-101 is a Z-Wave Plus device with a built-in temperature sensor, a tilt sensor that reports if it is moved, and gold-plated probes that can be extended on a cable. It runs on a single CR123A battery rated for about two years, or can be powered from a 12/24 V DC supply.
The catch: it only works through a Z-Wave controller, with no native Alexa, Google Home, HomeKit or Matter support, and it will not join a Zigbee network. In Home Assistant, it appears through Z-Wave JS as a water leak binary sensor. If you do not already run Z-Wave, pick a Zigbee sensor above instead.
Where should you put water leak sensors?
Put a sensor at every spot where a hose, seal or tank could fail, and where water would run for hours before you noticed. Start with the places a puddle would spread unseen:
- Under the kitchen sink, on the cabinet floor below the trap and supply pipes.
- Behind or beneath the washing machine and dishwasher, where a split hose empties into the void.
- Next to the boiler, hot water cylinder or header tank, ideally with a probe on a cable rather than a puck.
- Under the bath and beside the toilet cistern, plus any utility room floor.
- In a loft or basement where a tank overflow or a burst pipe would otherwise go unseen.
Set the sensor flat on the floor with the contacts touching the surface, and test it with a damp cloth once installed. If you are sensor-shopping for the rest of the house too, our door sensor, window sensor and smoke detector guides cover the other safety basics.
Do leak sensors stop the water?
No. A leak sensor only detects and reports water; it does not shut anything off. To act on an alert you need an automation that does something useful: flashing a light, sounding a smart speaker or messaging every member of the household. Where the water supply has a smart shut-off valve, a Home Assistant automation triggered by the moisture state can close it, but that needs a separate valve, not just a sensor. A sensor that only beeps is little use if you are on holiday, so choose one that reaches your phone through Home Assistant notifications or the maker's own app.
Water is also a damp and humidity problem in the air, not only on the floor. If your leak worry is really condensation, pair these with a smart dehumidifier or an air quality monitor that reports humidity.
Who should skip a smart leak sensor?
If you never plan to connect it to anything, a battery-powered standalone alarm with a loud siren is enough, and it will cost less. Smart sensors earn their keep when you are away, when the leak is in a hidden space, or when you want an automation to react. Renters should check with the landlord before adding a mains-powered unit, and anyone without a Zigbee, Z-Wave or Thread setup should think about the Shelly Flood Gen4 rather than buying a whole new hub for a single sensor.
Outdoor taps and hoses can leak too: if you are automating garden watering, the valves in our best smart irrigation controller UK guide pair well with a leak sensor near the outside tap.
