Winner
18% OFF
$32.99
$39.99
Updated October 2026
Data from the official Eufy and Shelly sites.
2026 verdict
Need years between battery changes? The eufy Security Flood & Freeze Sensor E20 is the better buy of these two water leak sensors, rated for roughly five years on its CR123A cell against the Shelly Flood's 1.5 years.
It is also the better reviewed of the pair, and it sounds a 75 dB buzzer and blinks its LED red on its own when it detects water or a freeze risk, something the Shelly Flood cannot do, plus it ships with a 1.2 m extension probe for gaps under appliances. The Shelly Flood answers back with a lower price, no hub of its own since it joins Wi-Fi directly, a wider list of integrations that includes Google Home, Samsung SmartThings and Home Assistant, and an everyday temperature reading the eufy sensor does not report. The eufy Security Flood & Freeze Sensor E20 also needs a compatible US eufy HomeBase to work at all, while the Shelly Flood needs no separate hub. Choose the eufy Security Flood & Freeze Sensor E20 for the longer battery, sealed IP54 housing, a local alarm and freeze alerts inside an existing HomeBase home; choose the Shelly Flood for a cheap, hub-free Wi-Fi sensor with broader platform support.
Works with
Connectivity
- Wi-Fi 2.4 GHz
vs
Price unavailable right now
Works with
Connectivity
- Wi-Fi 2.4 GHz
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| Feature | eufy Security Flood & Freeze Sensor E20 | Shelly Flood | Winner |
|---|---|---|---|
| Rating | 4.3 | 3.8 | eufy Security Flood & Freeze Sensor E20 |
| Battery Life | 5 years | 1.5 years | eufy Security Flood & Freeze Sensor E20 |
| Integrations | Home Assistant | Google Home, Samsung SmartThings, Home Assistant | Shelly Flood |
| Alerts | Water Leak Alerts, Freeze Temperature Alerts, Low Battery Alerts | Water Leak Alerts, Temperature Alerts, Freeze Temperature Alerts, Low Battery Alerts | Shelly Flood |
| On Device Alert Sound | YES | NO | eufy Security Flood & Freeze Sensor E20 |
| On Device Alert Light | YES | NO | eufy Security Flood & Freeze Sensor E20 |
| Connectivity | 2.4 GHz WiFi | 2.4 GHz WiFi | Tie |
| Sensors | Water Leak, Temperature | Water Leak, Temperature | Tie |
What the differences mean
Battery life
The eufy Security Flood & Freeze Sensor E20 is rated for about five years on its CR123A cell, against roughly 1.5 years on the Shelly Flood, which also does not include the battery in the box.
Local alarm
The eufy Security Flood & Freeze Sensor E20 sounds a 75 dB buzzer and blinks its LED red on the spot when it detects a leak or a freeze risk. The Shelly Flood has no on-device sound or light and relies on your hub or app.
Hub requirement
The Shelly Flood joins your Wi-Fi network directly with no separate hub. The eufy Security Flood & Freeze Sensor E20 needs a compatible US eufy HomeBase (Mini, HomeBase 2, 3 or Pro) to pair or send any alert at all.
Weather sealing
The eufy Security Flood & Freeze Sensor E20 carries an IP54 rating for damp utility spaces. Weather resistance is not documented for the Shelly Flood.
Temperature reporting
The Shelly Flood reports everyday ambient temperature alongside leak detection. The eufy Security Flood & Freeze Sensor E20 only watches for freeze risk below 4 C, with five alarm thresholds in the app, and does not report a general temperature reading.
Extras included
The eufy Security Flood & Freeze Sensor E20 ships with a 1.2 m extension probe for tight spots under appliances. The Shelly Flood has no probe or cable of its own.
Which one to buy if
- you already own a compatible eufy HomeBase
The eufy Security Flood & Freeze Sensor E20 slots straight into that system with its own local alarm and a five-year battery.
- you want a sensor with no separate hub to buy
The Shelly Flood joins Wi-Fi directly, with nothing else to add to the cart.
- the spot needs freeze protection more than a loud local alarm elsewhere
Its five freeze thresholds and 75 dB buzzer are built for exactly that job.
- the sensor has to reach under an appliance through a narrow gap
Its included 1.2 m probe is thin enough to slide where the round body will not fit.
- you want the widest platform reach for the lower price
The Shelly Flood covers Google Home, SmartThings and Home Assistant with no HomeBase to add.
Winner
18% OFF
$32.99
$39.99
- + Rating: 4.3
- + Battery Life: 5 years
- + On Device Alert Sound: YES
- - Integrations: Home Assistant vs Google Home, Samsung SmartThings, Home Assistant
- - Alerts: Water Leak Alerts, Freeze Temperature Alerts, Low Battery Alerts vs Water Leak Alerts, Temperature Alerts, Freeze Temperature Alerts, Low Battery Alerts
Price unavailable right now
- + Integrations: Google Home, Samsung SmartThings, Home Assistant
- + Alerts: Water Leak Alerts, Temperature Alerts, Freeze Temperature Alerts, Low Battery Alerts
- - Rating: 3.8 vs 4.3
- - Battery Life: 1.5 years vs 5 years
What owners say
Shelly Flood owners consistently praise the no-app setup: placing the battery starts a local Wi-Fi access point you join from a phone browser, and once it is on the network Home Assistant users say it gets picked up automatically with both flood and temperature data flowing in. Buyers also like that it is cheap enough to deploy one near every water source in the house. The recurring complaint is Wi-Fi reliability: a handful of owners describe a sensor dropping offline and needing to be manually reconnected, sometimes more than once, and initial pairing can take a few attempts before the network joins cleanly. A few also note the battery is not included and, being Wi-Fi rather than Zigbee or Z-Wave, tends to run down faster.
Frequently Asked Questions
Which is better overall: the eufy Security Flood & Freeze Sensor E20 or the Shelly Flood?
The eufy Security Flood & Freeze Sensor E20 wins overall, with a longer rated battery, a sealed IP54 body, and a local sound and light the Shelly Flood does not have. The Shelly Flood counters with a lower price, no separate hub and wider platform support.
What is the biggest difference between the eufy Security Flood & Freeze Sensor E20 and the Shelly Flood?
The hub. The Shelly Flood is a hub-free Wi-Fi sensor for leaks and temperature. The eufy Security Flood & Freeze Sensor E20 is a sealed, five-year battery disc with a local buzzer and freeze alerts, but it needs a compatible US eufy HomeBase to work.
Does the eufy Security Flood & Freeze Sensor E20 need a hub?
Yes. It talks over a Sub-1G radio to a compatible US eufy HomeBase (Mini, HomeBase 2, 3 or Pro). Without one it cannot pair or send an alert to your phone.
Does the Shelly Flood sound a local alarm?
No. The Shelly Flood has no on-device sound or light, so notifications depend on the app or your hub. The eufy Security Flood & Freeze Sensor E20 sounds a 75 dB buzzer and blinks its LED on the spot.
Who should buy the Shelly Flood?
Buyers who want a cheap, hub-free Wi-Fi sensor for leaks and everyday temperature, with Google Home, SmartThings and Home Assistant support and no extra hardware to add.
Who should buy the eufy Security Flood & Freeze Sensor E20?
Households already running a compatible eufy HomeBase who want the longest battery here, a sealed housing, freeze alerts and a local alarm loud enough to hear across a utility room.
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