18% OFF
$32.99
$39.99
Updated October 2026
Data from the official Eufy and Shelly sites.
2026 verdict
Its mix of protocols decides it: the Shelly Flood Gen4 is the more flexible water leak sensor than the eufy Security Flood & Freeze Sensor E20.
It speaks Wi-Fi, Zigbee, Bluetooth and Matter, reaches Apple Home and SmartThings through Matter plus Google Home and Home Assistant, and it carries the stronger owner rating and a 2 m extendable sensing cable. The eufy Security Flood & Freeze Sensor E20 answers with the longer battery, five years on a CR123A against two on the Shelly, the tougher sealing at IP54 against IP44, freeze thresholds and a 1.2 m probe. The eufy Security Flood & Freeze Sensor E20 still needs a US Eufy HomeBase. Pick the Shelly Flood Gen4 for a hub-free, multi-protocol install, and the eufy Security Flood & Freeze Sensor E20 for a Eufy home that wants freeze alerts and a battery that lasts.
Works with
Connectivity
- Wi-Fi 2.4 GHz
vs
Winner
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| Feature | eufy Security Flood & Freeze Sensor E20 | Shelly Flood Gen4 | Winner |
|---|---|---|---|
| Price | $32.99 | $39.99 | eufy Security Flood & Freeze Sensor E20 |
| Rating | 4.3 | 4.1 | eufy Security Flood & Freeze Sensor E20 |
| Weather Resistance | IP54 | IP44 | eufy Security Flood & Freeze Sensor E20 |
| Battery Life | 5 years | 2 years | eufy Security Flood & Freeze Sensor E20 |
| Connectivity | 2.4 GHz WiFi | 2.4 GHz WiFi, Bluetooth, Zigbee | Shelly Flood Gen4 |
| Integrations | Home Assistant | Google Home, Apple HomeKit, Samsung SmartThings, Home Assistant, Matter | Shelly Flood Gen4 |
| Alerts | Water Leak Alerts, Freeze Temperature Alerts, Low Battery Alerts | Water Leak Alerts, Temperature Alerts, Freeze Temperature Alerts, Low Battery Alerts | Shelly Flood Gen4 |
| Sensors | Water Leak, Temperature | Water Leak, Temperature | Tie |
| On Device Alert Sound | YES | YES | Tie |
| On Device Alert Light | YES | YES | Tie |
What the differences mean
Protocols
The Shelly Flood Gen4 supports Wi-Fi, Zigbee, Bluetooth and Matter, so it can join a Home Assistant, Zigbee2MQTT, Google Home, Apple Home or SmartThings setup. The eufy Security Flood & Freeze Sensor E20 talks sub-1G to a Eufy HomeBase and has no standard radio of its own.
Hub
The Shelly Flood Gen4 needs no hub at all and joins your network itself. The eufy Security Flood & Freeze Sensor E20 is inert without a compatible US Eufy HomeBase, which is what carries its Wi-Fi and phone alerts.
Sensing and cable
Both watch for water, temperature and freezing. The Shelly Flood Gen4 ships a 2 m extendable cable so the body can sit elsewhere, while the eufy Security Flood & Freeze Sensor E20 includes a 1.2 m probe and reports freeze thresholds rather than a general room reading.
Alerts
Both have a buzzer and an LED on the device, so each warns you locally as well as through the app. The Shelly Flood Gen4 also reports low battery, and the eufy Security Flood & Freeze Sensor E20 flashes its LED when the CR123A runs low.
Battery
The eufy Security Flood & Freeze Sensor E20 is rated for five years on a CR123A, more than double the two years of the Shelly Flood Gen4 on four AA cells. The trade is that the E20 only works inside its HomeBase.
Weather sealing
The eufy Security Flood & Freeze Sensor E20 is rated IP54 and the Shelly Flood Gen4 IP44, so the Eufy is the slightly better protected of the two. Both are indoor sensors, and neither should be hosed down or submerged.
Which one to buy if
- you want no hub and a sensor that fits any ecosystem
The Shelly Flood Gen4 supports Wi-Fi, Zigbee, Bluetooth and Matter and joins your network on its own.
- your home runs on Apple Home, Google Home or Matter
It reaches Apple Home and SmartThings through Matter and Google Home directly, with no vendor base station.
- you already own a US Eufy HomeBase
The eufy Security Flood & Freeze Sensor E20 drops into the app you already run, at the lower price of the pair.
- you want the longest battery life
It is rated for five years on a CR123A, well beyond the two years of the Shelly Flood Gen4.
- the leak point is under a cabinet or behind a heater
The Shelly Flood Gen4 includes the longer 2 m cable to place the sensing point where the water actually is.
18% OFF
$32.99
$39.99
- + Price: $32.99
- + Rating: 4.3
- + Weather Resistance: IP54
- - Connectivity: 2.4 GHz WiFi vs 2.4 GHz WiFi, Bluetooth, Zigbee
- - Integrations: Home Assistant vs Google Home, Apple HomeKit, Samsung SmartThings, Home Assistant, Matter
Winner
$39.99
- + Connectivity: 2.4 GHz WiFi, Bluetooth, Zigbee
- + Integrations: Google Home, Apple HomeKit, Samsung SmartThings, Home Assistant, Matter
- + Alerts: Water Leak Alerts, Temperature Alerts, Freeze Temperature Alerts, Low Battery Alerts
- - Price: $39.99 vs $32.99
- - Rating: 4.1 vs 4.3
What owners say
Owners of the Shelly Flood Gen4 are mostly Home Assistant and Zigbee2MQTT users, and they describe the same two wins: it pairs quickly and stays stable over Zigbee, and the included cable is sensitive enough that a single drop of water sets it off. The built-in buzzer and LED are valued for a local alert without the app, and the on-device automations let owners cut power to a pump or flash lights on a leak. The friction is mostly on the other radios. Several describe slow or fiddly Wi-Fi onboarding, and a smaller group pairing over Matter into Apple HomeKit found the leak status did not refresh without a button press. A few also wish the 4x AA battery lasted longer than the rated two years.
Frequently Asked Questions
Which is better overall: the eufy Security Flood & Freeze Sensor E20 or the Shelly Flood Gen4?
The Shelly Flood Gen4, for most homes. It needs no hub, supports Wi-Fi, Zigbee, Bluetooth and Matter and carries the stronger owner rating. The eufy Security Flood & Freeze Sensor E20 is the better value inside an existing Eufy HomeBase, where its five-year battery is the draw.
What is the biggest difference between the eufy Security Flood & Freeze Sensor E20 and the Shelly Flood Gen4?
Freedom from a hub. The Shelly Flood Gen4 joins your network directly over four radio options, while the eufy Security Flood & Freeze Sensor E20 cannot work without a compatible US Eufy HomeBase.
Do either of these water leak sensors need a hub?
Only the eufy Security Flood & Freeze Sensor E20, which needs a Eufy HomeBase. The Shelly Flood Gen4 needs no hub and can run on Wi-Fi, Zigbee or Matter on its own.
Which one works with Apple Home or Matter?
The Shelly Flood Gen4 does, reaching Apple Home and SmartThings through Matter. The eufy Security Flood & Freeze Sensor E20 has no Matter, Apple Home or Google Home path and reaches Home Assistant only through a community integration.
Which has the longer battery life?
The eufy Security Flood & Freeze Sensor E20, rated for five years on a CR123A against two years for the Shelly Flood Gen4 on four AA cells.
Who should buy the eufy Security Flood & Freeze Sensor E20?
A Eufy HomeBase household that wants a cheap, long-lasting leak and freeze disc with its own buzzer and probe, and does not need other platforms.
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