The Shelly Flood S Gen4 is a compact, battery-powered smart water leak sensor designed for early detection and prevention of water damage. The device can cover a large detection area and features stainless steel sensing feet. This allows it to respond quickly and reliably, even with clean or low-conductivity water. Its flat design makes it easy to place near or under washing machines, dishwashers, refrigerators, boilers, sinks, toilets, water filters, valves, and other risk areas.
The Flood S Gen4 is a point-detection sensor with an IP67-rated design. It is especially useful where compact size, direct floor placement, and fast alerts are important. It is ideal for kitchens, bathrooms, laundry rooms, boiler rooms, server rooms, holiday homes, utility rooms, and hard-to-reach corners.
The device supports Wi-Fi 6, Bluetooth 5 LE, and Zigbee 3.0 protocols, and it is also Matter-over-Wi-Fi compatible, allowing flexible integration into almost any smart home system. It can be used with the Shelly Smart Control app, Shelly Cloud, Home Assistant, SmartThings, and Matter-compatible ecosystems.
The Shelly Flood S Gen4 offers two operating modes: Flood Detection mode for water leak and flood alerts, and Rain Detection mode for rain detection. In Rain Detection mode, the device reports status changes without triggering an alarm, making it useful for outdoor automations such as stopping irrigation, retracting awnings, or closing roof windows.
The built-in speaker provides an immediate local alarm when water is detected, while three selectable alarm profiles — Intense, Normal, and Economic — allow operation to be adapted to the location. Intense mode is useful for protecting high-value equipment, laboratories, and server rooms; Normal mode is intended for general home use; and Economic mode is practical for holiday homes, weekend houses, and rarely visited properties.
The sensor operates on one CR123A battery, included in the package, and can provide up to approximately 2 years of battery life depending on usage, network quality, and the selected alarm profile. No wired power supply is required.
About Shelly
Shelly is one of Europe’s most recognized and innovative smart home brands, developed by the Bulgarian company Allterco Robotics. The manufacturer is particularly strong in Wi-Fi and Bluetooth-based smart devices, many of which can operate without a central hub, allowing fast and simple installation.
The Shelly product portfolio includes relays, sensors, smart plugs, lighting solutions, and professional DIN rail-mounted devices. The brand places strong emphasis on local control, meaning many devices can be used even without an internet connection, improving both reliability and data privacy.
Shelly devices offer advanced integration options, including REST API, MQTT, and Webhook support. They can be easily integrated with Home Assistant, openHAB, Node-RED, and other DIY platforms, while also supporting popular cloud platforms such as Google Home, Amazon Alexa, and Samsung SmartThings.
Key Features
- Large stainless steel sensing feet: Fast and reliable water detection, including clean or low-conductivity water
- Compact, flat design: Easy placement under appliances, sinks, near valves, or in hard-to-reach corners
- Flood and Rain modes: Separate operation for water leak alerts and rain detection
- Three alarm profiles: Intense, Normal, and Economic profiles for different use cases
- Built-in speaker: Local audible alarm for water detection or low battery status
- IP67 protection: High-level dust and water resistance
- Battery-powered operation: Uses 1 × CR123A battery, included in the package
- Up to approximately 2 years of battery life, depending on usage and network conditions
- Multi-protocol connectivity: Wi-Fi 6, Bluetooth 5 LE, and Zigbee 3.0 support
- Matter-over-Wi-Fi compatibility: Easy integration into Matter-compatible systems
- Local automations: Can work with other devices without cloud dependency in compatible systems
- Automatic water shut-off option: Can trigger a smart water valve to shut off water in case of leakage
Smart Home Protocols and Platform Compatibility
- Wi-Fi 6: Wireless connection based on 802.11 b/g/n/ax
- Bluetooth 5 LE: Energy-efficient connection for setup and local communication
- Zigbee 3.0: Low-power communication optimized for smart home sensor networks
- Matter-over-Wi-Fi: Support for Matter-compatible ecosystems
- Shelly Smart Control: Full native app control, notifications, and settings
- Shelly Cloud: Remote access and notifications via the internet
- Home Assistant: Integration via Shelly and compatible protocols
- Amazon Alexa: Can be used as a contact sensor function
- Google Home: Sensor status display supported
- Samsung SmartThings: Water Sensor and Battery capabilities supported
- MQTT: For local server-based integrations
- UDP: Local network communication support
- KVS: Key-Value Store support on the Gen4 platform
- Firmware profile switching: The device can be switched between Matter and Zigbee profiles
- Additional supported integrations: MQTT, HomeSeer, ioBroker, Home Assistant, openHAB, Domoticz, SYMCAN, nymea, Hubitat, HOOBS, and REST API
Smart Functions
- Instant water leak detection
- Push notifications to mobile phone
- Local audible alarm with built-in buzzer
- Flood Detection mode for immediate alerts
- Rain Detection mode for rain-based automations
- Intense alarm profile for critical locations
- Normal alarm profile for general home use
- Economic alarm profile for rarely visited properties and battery-saving operation
- Automatic water shut-off with a smart water valve
- Stop irrigation systems based on rain detection
- Control awnings, roof windows, or window motors in case of rain
- Monitor leaks around washing machines, dishwashers, or boilers
- Early detection of toilet tank, water connection, or wax ring issues
- Monitor water heater or boiler drip trays
- Protection for server rooms, laboratories, and technical areas
- Low battery indication
- OTA firmware update with status indication
- Identification mode for physically locating the device
- Network reset and factory reset using the built-in button
Additional Features
- Compact point-type water leak sensor
- Not a sensor cable-based model
- Large stainless steel sensing surfaces
- IP67 dustproof and water-resistant design
- Can be placed on a flat surface
- Suitable for placement under appliances and in hard-to-reach areas
- Suitable for kitchens, bathrooms, laundry rooms, boiler rooms, holiday homes, server rooms, and utility areas
- LED status indication for Wi-Fi, Zigbee, OTA, and identification states
- Short audible alert for low battery, except in certain alarm modes
- Alarm can be muted by pressing the button or when water is no longer detected
Technical Specifications
- Product name: Shelly Flood S Gen4
- Model: S4SN-0071Z
- Device SSID: ShellyFloodSG4-XXXXXXXXXXXX
- BLE Model ID: 0x1826
- Dimensions: 23 × 77 mm
- Weight without battery: 50 g
- Weight with battery: 70 g
- Installation / placement: Can be placed on a flat surface
- Housing material: Plastic
- Housing color: White
- Protection rating: IP67
- Operating temperature: -20°C to +40°C
- Operating humidity: 30% to 100% RH
- Maximum installation altitude: 2000 m
- Power supply: Battery
- Battery type: 1 × CR123A
- Battery included: Yes
- Expected battery life: Approximately 2 years
- Water detection: Yes
- Sensing surface: Large stainless steel sensing feet
- Wi-Fi protocol: 802.11 b/g/n/ax
- Wi-Fi frequency: 2401–2483 MHz
- Wi-Fi maximum RF power: < 20 dBm
- Wi-Fi range: Up to 30 m indoors, 50 m outdoors
- Bluetooth protocol: Bluetooth 5 LE
- Bluetooth frequency: 2402–2480 MHz
- Bluetooth maximum RF power: < 20 dBm
- Bluetooth range: Up to 10 m indoors, 30 m outdoors
- Zigbee protocol: 802.15.4
- Zigbee frequency: 2405–2480 MHz
- Zigbee maximum RF power: < 20 dBm
- Zigbee range: Up to 100 m indoors, 300 m outdoors
- Matter support: Matter-over-Wi-Fi
- CPU: ESP-Shelly-C68F
- Flash memory: 8 MB
- Timers: Not supported
- Webhooks: 10 webhooks, up to 2 URLs per webhook
- Scripting: Not supported
- MQTT: Yes
- UDP: Yes
- KVS: Yes
- Alarm profiles: Intense, Normal, Economic
- Operating modes: Flood Detection and Rain Detection
- Audible alarm: Built-in buzzer
- LED status indication: AP mode, Wi-Fi connection, Shelly Cloud connection, Zigbee pairing, OTA update, and identification
- Button functions: Wake-up, status report, sleep mode, Zigbee pairing, Matter/Zigbee switching, network reset, factory reset
