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Water Leak Sensors · Head to head

Shelly Flood Gen4 vs Third Reality Water Leak Sensor

Full Smart Water Leak Sensors comparison in 2026

Updated September 2026
Data from Amazon and official Shelly and Third Reality sites.
2026 verdict
Multi-protocol flexibility versus a 120 dB bark: the Shelly Flood Gen4 is the more complete water leak sensor of the two, with temperature sensing and Matter on top of a local alarm.
Shelly Flood Gen4
Winner
Shelly Flood Gen4
$39.99
Buy on Amazon USACheck price
It connects over Wi-Fi, Zigbee or Bluetooth, works natively with Google Home and Home Assistant and through Matter with Apple Home and SmartThings, sends freeze alerts, ships with a 2 m sensing cable, and is the better reviewed of the pair with a 3-year warranty. The Third Reality Water Leak Sensor is the lower priced, simpler Zigbee option: its 120 dB alarm is louder, it runs a rated 3 years on two AAA cells against 2 years on four AA, and it pairs quickly with Home Assistant, Hubitat or SmartThings. Choose the Shelly Flood Gen4 if you want one sensor that fits any platform, and the Third Reality Water Leak Sensor to cover many spots on a Zigbee network for less.
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FeatureShelly Flood Gen4Third Reality Water Leak SensorWinner
Price$39.99$20.99Third Reality Water Leak Sensor
Rating4.24.1Shelly Flood Gen4
Warranty3 years1 yearShelly Flood Gen4
Battery Life2 years3 yearsThird Reality Water Leak Sensor
Connectivity2.4 GHz WiFi, Bluetooth, ZigbeeZigbeeShelly Flood Gen4
IntegrationsGoogle Home, Apple HomeKit, Samsung SmartThings, Home Assistant, MatterGoogle Home, Apple HomeKit, Samsung SmartThings, Home AssistantShelly Flood Gen4
SensorsWater Leak, TemperatureWater LeakShelly Flood Gen4
AlertsWater Leak Alerts, Temperature Alerts, Freeze Temperature Alerts, Low Battery AlertsWater Leak Alerts, Low Battery AlertsShelly Flood Gen4
On Device Alert LightYESNOShelly Flood Gen4
On Device Alert SoundYESYESTie

What the differences mean

Platforms and radios

The Shelly Flood Gen4 joins Wi-Fi, Zigbee or Bluetooth and supports Matter, which brings Apple Home and SmartThings. The Third Reality Water Leak Sensor is Zigbee only, works with SmartThings and Home Assistant, and needs its Smart Bridge MZ1 for Google Home and Apple Home.

Temperature and freeze alerts

The Shelly Flood Gen4 measures temperature and warns before pipes freeze. The Third Reality Water Leak Sensor detects water only.

Local alarm

Both alert on the device. The Third Reality Water Leak Sensor is the louder one with a 120 dB alarm; the Shelly Flood Gen4 has a buzzer plus an LED indicator, which the Third Reality lacks.

Sensing cable

The Shelly Flood Gen4 includes a 2 m extendable sensing cable for leaks under cabinets or along a run of pipe. The Third Reality Water Leak Sensor senses at its base and includes a drip attachment for slow leaks.

Batteries

The Third Reality Water Leak Sensor is rated for 3 years on two AAA cells, the Shelly Flood Gen4 for 2 years on four AA. Both use batteries you can buy anywhere.

Which one to buy if

What owners say

Owners of both sensors are largely Home Assistant users, and both groups describe Zigbee pairing that is quick and stable. Shelly Flood Gen4 owners single out a sensing cable that triggers on a single drop, a buzzer and LED for local alerts and on-device automations that switch other Shelly devices, while their complaints are slow Wi-Fi onboarding and Apple Home status over Matter that sometimes did not refresh. Third Reality Water Leak Sensor owners talk above all about an alarm loud enough to hear from another floor and value that lets them run a dozen units, and they warn that the sensing screws sit slightly raised, so shallow water may not reach them without spacers or the drip attachment, and that a few units went offline or drained batteries after a year or more.

Price history compared

Every price change of both, in the same store, so the gap between the two lines is what one costs more than the other.

  • Shelly Flood Gen4
  • Third Reality Water Leak Sensor

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Frequently Asked Questions

Which is better overall: Shelly Flood Gen4 or Third Reality Water Leak Sensor?

The Shelly Flood Gen4. It supports Wi-Fi, Zigbee, Bluetooth and Matter, adds temperature and freeze alerts and a sensing cable, and has a 3-year warranty. The Third Reality Water Leak Sensor is the cheaper, louder Zigbee-only alternative.

What is the biggest difference between the Shelly Flood Gen4 and the Third Reality Water Leak Sensor?

Reach. The Shelly Flood Gen4 works on almost any platform, including Apple Home through Matter, while the Third Reality Water Leak Sensor is a Zigbee device that needs a Zigbee hub and a separate bridge for Google Home and Apple Home.

Do the Shelly Flood Gen4 and the Third Reality Water Leak Sensor need a hub?

The Shelly Flood Gen4 does not: it can join Wi-Fi directly, or a Zigbee hub if you prefer. The Third Reality Water Leak Sensor needs a Zigbee hub such as Home Assistant, Hubitat or SmartThings.

Which is louder, the Shelly Flood Gen4 or the Third Reality Water Leak Sensor?

The Third Reality Water Leak Sensor, with a 120 dB alarm. The Shelly Flood Gen4 has a built-in buzzer for local alerts plus an LED.

Who should buy the Shelly Flood Gen4?

Anyone who wants one leak and freeze sensor that fits Home Assistant, Apple Home, Google Home or SmartThings, with a cable for hard-to-reach spots.

Who should buy the Third Reality Water Leak Sensor?

Zigbee households, especially Home Assistant and Hubitat users, who want a loud alarm on every sensor and an affordable way to cover many spots.

Full comparison table

Compare all 33 Water Leak Sensors side by side

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