Water damage is one of those problems where a single sensor can save you a major repair bill on your floors, cabinets, etc. Leak sensors have been among the best values in the smart home for years, and Shelly’s new Flood S Gen4 makes it even easier to get started. It’s under $30, Matter-certified, and works with Apple Home out of the box.

HomeKit Weekly is a series focused on smart home accessories, automation tips and tricks, and everything to do with Apple’s smart home framework.

Bigger sensors

Most leak sensors on the market today use small metal pins on the bottom, which means water has to pool in exactly the right spot before anything triggers. Shelly went a different direction with its new sensor, with three large stainless steel pads spread across the bottom of the unit. A larger contact area means water is detected faster and in more places, which is the whole point of putting a sensor under a water heater or washing machine in the first place.

The pads are also sensitive enough to detect clean or low-conductivity water, such as AC condensate. These leaks are often a lot harder to detect. The Flood S Gen4 is also low profile enough to slide under appliances, behind toilets, and beneath sinks, which is exactly where you want these things to live.

Matter/Apple Home support

The Flood S Gen4 is Matter certified and supports Wi-Fi and Zigbee, so it works with Apple Home, Google Home, Amazon Alexa, SmartThings, and Home Assistant. Once it’s in Apple Home, the automation possibilities open up:

  • Cut power to a washing machine or dishwasher the moment water is detected (if it’s on a smart outlet)
  • Trigger every smart bulb in your house
  • Simple alerts to your iPhone of a leak detected (incredibly helpful if out of town)

Modes, alarms, and battery life

There’s a built-in local alarm alongside the phone notification, so anyone actually in the house hears it even if their phone is in another room. Shelly includes two operating modes, flood detection and rain detection, plus three alarm profiles (intense, normal, and economic) that let you balance a leak detection speed against battery life. It runs up to two years on the included CR123A battery.

Wrap up

At under $30, this is the kind of accessory you buy 3-4 of without thinking. In front of the water heater, in front of the dishwasher, under the washing machine, and under the kitchen sink. Matter/Apple Home support lets you get alerts from the Home app and build your Apple Home automations around it. There’s a lot to like here, and nothing I don’t like. Trust me, a water sensor detector is the smartest investment you can buy for a smart home.

You can buy the Shelly Flood S Gen4 from Amazon or directly from Shelly.

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