Water damage is one of those problems where a single sensor can save you a major repair bill. Shelly's new Flood S Gen4 makes it easy to get started. It's under $30, Matter-certified, and works with Apple Home out of the box.

Most leak sensors use small metal pins, requiring water to pool in the right spot. Shelly's sensor has three large stainless steel pads across the bottom, detecting water faster and in more places. The pads also detect clean or low-conductivity water, like AC condensate. The Flood S Gen4 slides under appliances, behind toilets, and beneath sinks.

The Flood S Gen4 is Matter certified and supports Wi-Fi and Zigbee, working with Apple Home, Google Home, Amazon Alexa, SmartThings, and Home Assistant. In Apple Home, you can cut power to a washing machine or dishwasher when water is detected, trigger smart bulbs, and get iPhone alerts. There's a built-in local alarm, two operating modes (flood and rain detection), and three alarm profiles. It runs up to two years on the included CR123A battery.

At under $30, this is the kind of accessory you buy 3-4 of without thinking. Matter/Apple Home support lets you get alerts from the Home app and build automations. There's a lot to like here, and nothing I don't like.