Shelly Flood Gen4 Review: Cable-Based Water Detection Comes to Apple Home via Matter

Nothing induces homeowner anxiety quite like the threat of undetected water leaks. While puck-style sensors have been a staple in smart homes, their fundamental limitation is spatial: water must directly contact a specific small surface area to trigger an alert. This leaves appliances like washing machines, water heaters, and basement piping vulnerable to leaks originating outside their detection radius. The Shelly Flood Gen4 directly addresses this vulnerability with its cable-based detection system, bringing a new level of protection to Apple Home environments through Matter integration.

The Sensing Cable: Redefining Leak Detection Coverage

At the core of the Flood Gen4 is a flexible 1.8-meter (6-foot) detection cable that functions as a continuous tripwire for liquid. Unlike puck sensors that monitor a single point, this cable creates a perimeter defense around appliances or along vulnerable piping. Water contacting any segment of the cable triggers an immediate alert. This design is particularly effective for:

• Large appliances: Wrap the cable around the base of washing machines or dishwashers
• Water heaters: Create a containment circle to catch leaks from pressure valves or tank seams
• Basement floors: Run along pipe runs or foundation walls where condensation occurs

The cable uses conductive sensing technology where electrical resistance changes when liquid bridges the embedded contacts. Shelly includes connectors for daisy-chaining additional cables (sold separately), enabling coverage of complex layouts like utility rooms or furnace areas. During testing, the coiled cable exhibited significant tension—a positive indicator of durable construction—though initial installation requires temporary clips or tape until it relaxes.

Matter Integration: Native Apple Home Support Without Bridges

Previous Shelly devices required complex integrations like Homebridge for Apple Home compatibility. The Gen4 changes this with native Matter 1.2 support over Wi-Fi. Setup is streamlined:

1. Insert two AA batteries (included)
2. Scan Matter QR code via Apple Home app
3. Device appears as "Water Sensor" in Home within seconds

This direct integration enables critical functionality:

• Instant push notifications to iPhone/Apple Watch upon leak detection
• Automation triggers (e.g., "If flood detected, shut off smart valve")
• Status visibility in Home app's dashboard

Battery life is rated at two years under normal use, aided by Shelly's dual monitoring modes:

Mode	Polling Interval	Use Case
Economic	60 minutes	Vacation homes, long-term monitoring
Intense	15 seconds	High-risk areas, instant alerts

Installation Insights and Real-World Performance

Positioning the sensor requires strategic planning. Ideal placements include:

• Under sink cabinets (route cable along pipe junctions)
• Behind toilets (loop around base)
• Near sump pumps or water softeners

The sensor base includes a magnetic mount and adhesive pads for flexible placement. During testing, alerts consistently reached Apple Home within 3 seconds of water contact. False triggers were nonexistent—the sensor correctly ignored high humidity and minor splashes.

Compared to puck-style alternatives like Aqara or Eve Water Guard, the Gen4 provides superior coverage at the cost of higher visibility (the cable can't be concealed like a puck). For whole-appliance protection, this trade-off is justified.

When to Choose the Shelly Flood Gen4

This sensor excels in scenarios where traditional pucks fall short:

• Secondary properties: Use Economic mode for remote monitoring
• Flood-prone basements: Daisy-chain cables along perimeter walls
• Appliance clusters: Single sensor coverage for multiple units

Limitations include no built-in siren (relies on HomePod alerts) and Wi-Fi dependency (consider battery backup for routers in flood zones).

Conclusion: Comprehensive Leak Defense Simplified

The Shelly Flood Gen4 ($49.99) eliminates puck sensors' blind spots through intelligent cable design while leveraging Matter for frictionless Apple Home integration. For homeowners seeking appliance-level protection against catastrophic leaks, it's an essential upgrade. Available directly from Shelly or Amazon.