Smart Water Leak Detectors and Automatic Shutoff Valves: Local Picks for 2026

Our picks at a glance

These are our picks based on published specs, Home Assistant integration data and the makers' documentation, checked in October 2026. We haven't run lab tests, and Kotoh Home takes no commissions from any brand here.

How a leak system works

A complete system has three parts:

1. Sensors sit on the floor where water would show up first. When their contacts get wet, they report a leak.
2. A hub receives the alert and decides what to do: notify you, sound an alarm, and close the water.
3. A shutoff valve on the main water line closes on command, stopping the flow until someone fixes the problem.

Sensors alone tell you there's a problem. Add the valve and the house stops the damage itself, which matters most when nobody is home to act on an alert. That's why leak protection is the first thing we suggest for second homes. Our guide to freeze, leak and power alerts for second homes covers it alongside the other risks.

Why local matters for leaks

A leak doesn't wait for the internet. If your sensors and valve depend on a company's cloud, a storm that knocks out the internet can also disable the system that's supposed to protect the house. Z-Wave and Zigbee sensors talk to a hub in the house over their own radio network. The hub can close a valve locally in seconds, with or without the internet. The internet only carries the alert to your phone.

Home Assistant labels the Moen Flo, Flume and YoLink integrations as cloud-based. They can still be good products, but their automations depend on the companies' servers. Z-Wave devices like Zooz's run locally through Home Assistant's Z-Wave integration.

Best local sensor: Zooz ZSE42

The ZSE42 is a small Z-Wave leak sensor, 0.3 inches thick, powered by a single CR2032 coin battery. It's an 800-series device with Z-Wave Long Range support, which Zooz says can reach up to 1,300 feet with compatible hubs. That matters in large houses where a basement water heater is far from the hub. Zooz notes it's splash-resistant but not waterproof and can't be submerged, which is normal for floor sensors; it's meant to detect water, not sit in it. It pairs with S2 security and SmartStart QR codes, and carries a five-year warranty on registration.

Best local shutoff: Zooz ZAC36 Titan

The ZAC36 Titan is a valve actuator: a motor that clamps onto the quarter-turn ball valve you probably already have on your main water line, and turns it for you. That means no cutting pipes for many homes. Zooz lists these details:

• Fits: 0.5 to 1.25-inch ball valves, with 3 inches of clearance on each side of the valve.
• Fail-safe probe: a built-in wired leak probe closes the valve "even if all wireless communication fails."
• Power: a 12-volt DC adapter, with an optional backup battery sold separately.
• Weather: IP66 rated, so it can be mounted where a main valve is often found, in a basement, crawlspace or garage.
• Extras: a temperature sensor, auto-calibration to the valve position, and it acts as a Z-Wave repeater.

Paired with Home Assistant, any leak sensor in the house can tell it to close. Add the backup battery so it can still close the valve during a power cut.

For UniFi homes: SuperLink Environmental

If the house runs on UniFi, Ubiquiti's SuperLink Environmental sensor ($49 on October 12, 2026) detects water leaks, temperature, humidity and light, and reports through UniFi Protect. It was listed as out of stock in early October, so check availability. It's a good way to keep cameras, alarm and leak alerts in one app.

Whole-home monitors: Moen Flo and Flume

Moen Flo is an inline smart valve installed on the main line. Home Assistant's integration reports flow rate, water pressure, temperature and daily use, and can open and close the valve. Because it watches flow, it can catch leaks that floor sensors can't see, such as a pipe dripping inside a wall. The trade-offs are a plumber installation and a cloud-based integration.

Flume clips onto your water meter and watches usage in real time to spot small leaks and unusual activity. It can't shut anything off, but it's a low-effort way to see whether water is running when it shouldn't be. Its Home Assistant integration is also cloud-based.

Actuator, inline valve or flow monitor?

Check your main valve first

A valve actuator is only as good as the valve it turns. Old gate valves with round handles don't work with clamp-on actuators, and a ball valve that hasn't been turned in years may be too stiff or may not seal fully. Before you buy anything, find your main shutoff, check its type and size, and turn it off and on once. If it's a gate valve or it doesn't close cleanly, have a plumber replace it with a full-port ball valve. That's worth doing for safety anyway.

For many second homes, the best answer is both: floor sensors and an actuator for local, automatic shutoff, plus a flow monitor for the slow, hidden leaks that sensors miss.

Where to put leak sensors

Put each sensor at the lowest point where water would collect, flat on the floor. In a pan under a water heater or washer, put it inside the pan.

Automations worth setting up

• Close and alert: any sensor gets wet, the main valve closes, every phone on the list gets a text, and a siren chirps in the house.
• Away mode: close the main water automatically when the house is empty for more than a day, and reopen it on arrival.
• Freeze guard: if a basement or crawlspace sensor reports near-freezing temperatures, raise the heat on a locally controlled thermostat and alert the caretaker.
• Health checks: alert if any sensor stops reporting or its battery runs low, so a dead sensor doesn't give false comfort.
• Monthly exercise: close and reopen the valve on a schedule so it doesn't seize from disuse.

Where Kotoh Home fits

Kotoh Home installs leak sensors and shutoff valves as part of a private smart home, alongside a self-monitored security system, with alerts routed to you, your caretaker or your plumber. It runs locally on the Home Assistant hub in every tier, and an optional cellular backup keeps alerts flowing during an internet outage. See our second-home monitoring service, or our checklist for closing up a house for winter.