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Water Leak Sensors · Head to head

Flume 2 Smart Water Monitor vs Shelly Flood Gen4

Full Smart Water Leak Sensors comparison in 2026

Updated September 2026
Data from Amazon and official Flume and Shelly sites.
2026 verdict
Guarding a single spot like under a cabinet or a water heater is where the Shelly Flood Gen4 wins this pair, sweeping nearly every measured category against the Flume 2 Smart Water Monitor.
Shelly Flood Gen4
Winner
Shelly Flood Gen4
$39.99
Buy on Amazon USACheck price
It leads on price, owner rating, connectivity, integrations, sensing breadth and alert coverage, plus a built-in buzzer and LED the Flume does not have at all. That sweep does not erase what each device is actually built to do, though: the Shelly Flood Gen4 is still a point sensor with a 2-meter extendable cable, so it only knows about water that touches its own contacts or cable, while the Flume 2 Smart Water Monitor straps to the existing water meter and reads every drop the whole house uses, the only way here to catch a leak that never touches a floor, like a slow toilet flapper or a buried irrigation line. Buy the Shelly Flood Gen4 for a flexible, multi-protocol sensor watching one specific spot with a loud local alarm; buy the Flume 2 Smart Water Monitor if you want one device watching the entire property instead of guessing where to place a sensor.
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FeatureFlume 2 Smart Water MonitorShelly Flood Gen4Winner
Price$199.00$39.99Shelly Flood Gen4
Rating4.04.2Shelly Flood Gen4
Connectivity2.4 GHz WiFi, Other2.4 GHz WiFi, Bluetooth, ZigbeeShelly Flood Gen4
IntegrationsGoogle Home, Home AssistantGoogle Home, Apple HomeKit, Samsung SmartThings, Home Assistant, MatterShelly Flood Gen4
SensorsWater LeakWater Leak, TemperatureShelly Flood Gen4
AlertsWater Leak Alerts, Low Battery AlertsWater Leak Alerts, Temperature Alerts, Freeze Temperature Alerts, Low Battery AlertsShelly Flood Gen4
On Device Alert SoundNOYESShelly Flood Gen4
On Device Alert LightNOYESShelly Flood Gen4
Weather ResistanceYESIP44Tie

What the differences mean

What each one sees

The Shelly Flood Gen4 detects water at its own contacts or along its 2-meter cable. The Flume 2 Smart Water Monitor reads the whole-house water meter, catching leaks anywhere on the property.

Radios

The Shelly Flood Gen4 supports Wi-Fi, Zigbee, Bluetooth and Matter. The Flume 2 Smart Water Monitor uses Wi-Fi through its bridge and a proprietary long-range radio between the meter sensor and the bridge, with no Zigbee, Bluetooth or Matter.

Local alarm

The Shelly Flood Gen4 has a built-in buzzer and LED. The Flume 2 Smart Water Monitor has no siren or light on either the meter sensor or the bridge, so alerts are app-only.

Platform reach

The Shelly Flood Gen4 reaches Google Home, Apple HomeKit, Samsung SmartThings and Home Assistant. The Flume 2 Smart Water Monitor reaches Google Home and Home Assistant only.

Power

The Shelly Flood Gen4 runs on 4x AA batteries. The Flume 2 Smart Water Monitor's meter sensor runs on a proprietary lithium pack, and its indoor bridge plugs into mains.

Which one to buy if

What owners say

Flume 2 Smart Water Monitor owners write about catches a floor sensor could never make, one credits it with finding a toilet flapper leaking into the bowl and another with flagging a hidden leak they would not otherwise have noticed, and installation strapping onto the existing meter is described as quick with no plumber involved. The recurring complaint is Flume's move to a proprietary replacement battery pack, which some owners call a real downgrade, and one owner found the per-fixture usage breakdown less precise than the marketing suggested. Shelly Flood Gen4 owners, especially those pairing it over Zigbee with Home Assistant, describe fast and stable connections and a cable sensitive enough to catch a single drop under a cabinet, plus a built-in buzzer that warns locally without the app, though a handful say the Wi-Fi and Matter or HomeKit pairing path was fiddlier than the Zigbee one.

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.

  • Flume 2 Smart Water Monitor
  • Shelly Flood Gen4

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Frequently Asked Questions

Which is better overall: Flume 2 Smart Water Monitor or Shelly Flood Gen4?

The Shelly Flood Gen4 wins on nearly every measured category: price, owner rating, connectivity, integrations, sensing breadth and alert coverage, and it has a local buzzer and LED the Flume 2 Smart Water Monitor lacks. The Flume still does one thing the Shelly cannot: watch the entire house from the water meter instead of one placement.

What is the biggest difference between the Shelly Flood Gen4 and the Flume 2 Smart Water Monitor?

What each one can actually see. The Shelly Flood Gen4, even with its extendable sensor cable, only detects water that reaches its own contacts. The Flume 2 Smart Water Monitor reads your whole-house water meter, catching a leak anywhere on the property, including ones that never touch a floor.

Does either one have a local alarm?

Only the Shelly Flood Gen4 does, with a built-in buzzer and an LED indicator. The Flume 2 Smart Water Monitor has no siren or light on either the meter sensor or its indoor bridge, so every alert is app-only.

Which one supports more smart home platforms?

The Shelly Flood Gen4 does. It connects over Wi-Fi, Zigbee, Bluetooth and Matter, reaching Google Home, Apple HomeKit, Samsung SmartThings and Home Assistant. The Flume 2 Smart Water Monitor works with Google Home and Home Assistant, with no Alexa, Apple HomeKit, SmartThings or Matter support.

Who should buy the Shelly Flood Gen4?

DIY smart home builders who want a flexible, multi-protocol sensor for a specific spot like under a cabinet or water heater, with a local alarm and room to fit into almost any hub setup.

Who should buy the Flume 2 Smart Water Monitor?

Homeowners who want to catch a leak anywhere on the property without placing individual sensors at every fixture, especially those with irrigation, a pool, or unexplained water bills.

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