Shelly
Shelly Flood Gen4
- Native integration
- Local control
- Zigbee
- Wi-Fi
- Matter
- Bluetooth
Prices verified September 2026
See more sensors picks on our Amazon storefront →Our verdict
The most flexible flood sensor Shelly's made — pick Wi-Fi, Zigbee, Bluetooth or Matter at setup, joining whatever mesh you already run, with a 2m cable extendable to 150m for reaching under a tank or behind an appliance. For most UK Home Assistant users we'd pick Wi-Fi: it's the only mode that gets full local RPC integration via mDNS auto-discovery, no cloud, no extra Zigbee coordinator. Tuck the sensor body out of sight and run the cable to the risk point — under the sink trap, behind the washing machine hose, or along a boiler's pressure-relief pipe. Commit to one radio at pairing; you can't run several at once.
What can Home Assistant control on the Shelly Flood Gen4?
| Control | Type | What it does |
|---|---|---|
| Leak | Binary sensor | Detects water contact along the sensor cable; 'wet' when moisture is present |
| Cable unplugged | Binary sensor | Diagnostic entity flagging a disconnected leak sensor cable (HA 2025.10.0+; requires a device re-add on existing installs) |
| Battery | Sensor (%) | Remaining battery percentage |
Uses HA's built-in Shelly integration over local RPC (HTTP/WebSocket via Gen2+ protocol), auto-discovered by mDNS — no cloud account needed. Support for Flood Gen4 was merged into HA core via PR #136981; a separate 'cable unplugged' diagnostic binary_sensor landed later in HA 2025.10.0, so if you're updating from an older HA version you'll need to remove and re-add the device for that entity to show up. As a battery device, wake it with its button before pairing. A useful automation: trigger a push notification and close a smart water shut-off valve (e.g. via a Shelly relay) the moment the leak binary_sensor goes 'on'.
Specs
| battery | 4x AA 1.5V (included) |
|---|---|
| ip rating | IP44 |
| dimensions | 97 x 76 x 25 mm |
| battery life | manufacturer claims approx. 2 years |
| cable length | 2m, extendable up to 150m via additional cables |
| connectivity | Wi-Fi 802.11b/g/n/ax, Bluetooth 5 LE, Zigbee 3.0, Matter over Wi-Fi (select one mode at setup) |
| price position | At £33.60 it's roughly double the Zigbee-only Aqara Water Leak Sensor (£17.99) — the premium buys multi-protocol flexibility, a 150m-extendable cable, and full local RPC support via HA's native Shelly integration rather than a generic Zigbee entity |
| detection modes | Flood and rain detection, 3 alarm sensitivities (Intense, Normal, Economic) |
| operating temperature | -20°C to 40°C |
How does the Shelly Flood Gen4 compare?
| Product | From | Protocol | Local control | Integration |
|---|---|---|---|---|
| Shelly Flood Gen4 (this product) | £33.6 | Wi-Fi, Zigbee, Bluetooth, Matter | Yes | Native |
| Aqara Door and Window Sensor P2 | £23.99 | Matter, Thread | Yes | Works with HA |
| Aqara Motion Sensor P1 | £18.99 | Zigbee | Yes | Zigbee2MQTT / ZHA |
| Aqara Multi-State Sensor P100 | £25.49 | Zigbee, Thread, Matter | Yes | Zigbee2MQTT / ZHA |
Frequently asked questions
- Does the Shelly Flood Gen4 work with Home Assistant locally?
- Yes. The Shelly Flood Gen4 is controlled locally in Home Assistant through a built-in Home Assistant core integration (shelly), so it keeps working if your internet connection or the Shelly cloud goes down. Control and state updates stay on your own network.
- Which protocol does the Shelly Flood Gen4 use, and do I need a hub?
- The Shelly Flood Gen4 uses Wi-Fi and Zigbee and Bluetooth and Matter. To pair it with Home Assistant you need no hub — it joins your Wi-Fi network directly; or a Zigbee coordinator (for example a SkyConnect/ZBT-1 or Sonoff dongle) attached to your Home Assistant host; or a Bluetooth adapter on your Home Assistant host or an ESPHome Bluetooth proxy; or a Thread border router if it is Matter-over-Thread, or just your Wi-Fi network if it is Matter-over-Wi-Fi. Shelly's own hub is not required when you integrate through a built-in Home Assistant core integration (shelly).
- How much does the Shelly Flood Gen4 cost in the UK?
- The lowest price we have listed for the Shelly Flood Gen4 is £33.60 at The Pi Hut. Prices were last checked in September 2026 and change often, so confirm on the retailer's page before buying.