What Shelly Flood does well
Shelly Flood is an excellent product — for simple leak detection. Here's what it does well:
- Low price: The current Shelly Flood Gen4 costs €34.90 in Shelly's own shop, the compact Flood S Gen4 €18.90. Covering several rooms stays affordable.
- No hub required: Shelly Flood connects directly via WiFi. If you already run Zigbee or Matter, you can connect it that way instead.
- Open for smart homes: MQTT, webhooks, a local web interface and local automations. Home Assistant, Alexa, Google Home and SmartThings are supported.
- Local alarm: A built-in buzzer beeps when it detects water. The device runs on four AA batteries (about 2 years according to Shelly) — so the buzzer works without mains power too.
- Sensor cable: The included 2 m cable detects water along its full length and can be extended up to 150 m.
Why Shelly Flood falls short in a pump sump
The problem: Shelly Flood only reports whether water touches its contacts or its sensor cable. In a pump sump, that isn't enough — for several reasons:
- Too late on the floor: If the Shelly Flood sits on the basement floor, it only alerts once the sump has already overflowed.
- A single trigger point: You can hang the Gen4's sensor cable into the shaft. It then alerts as soon as the water reaches that height. How high the water is, how fast it's rising or whether it's falling again — you can't see that.
- Power outages: The buzzer keeps beeping on battery power. But if your router goes down with the power, no push notification gets through — and your pump has stopped. The Shelly Flood doesn't report the power cut itself.
- No pump monitoring: Shelly Flood cannot detect whether your pump is still running, cycling too infrequently, or has failed entirely.
- WiFi dependency: Basement WiFi is often weak. Without a connection to the router (or the Zigbee/Matter hub), all that's left is the beep on site.
Feature comparison
| Feature | Drainbee | Shelly Flood |
|---|---|---|
| Continuous water level monitoring | ||
| Alert on water contact (floor level) | ||
| Submersible probe for the shaft | ||
| Alert during power outage | ||
| Pump cycle and inflow history | ||
| Home Assistant / MQTT integration | ||
| No hub required | ||
| Alert on WiFi loss | ||
| Adjustable level threshold | ||
| Audible alarm on the device | ||
| Self-learning thresholds |
When do you need which?
Choose Shelly Flood if …
- You want affordable protection for the kitchen, bathroom, or laundry room
- You have an existing smart home system (Home Assistant, MQTT) and want to expand it
- You want to equip multiple rooms with leak sensors without spending a fortune
- You don't need to monitor a pump sump or drainage shaft
Choose Drainbee if …
- You want to monitor a pump sump, drainage system, or shaft
- You want to be warned before water reaches the basement
- You want to see in the history how often your pump runs and how much water flows in
- You want alerts even during power outages (if power or WiFi drops, the Drainbee cloud notices the device has gone offline and alerts you in the app)
- You don't want to find out about flooding only after it's happened
Or both: Shelly Flood in the kitchen and bathroom — Drainbee in the pump sump. Both systems work independently.
Verdict
Shelly Flood is an excellent water sensor for the price. For about €35 you get a reliable sensor that fits almost any smart home and beeps loudly on site. For leak detection under the dishwasher, in the bathroom, or in the laundry room, you can hardly do better.
But for the pump sump, Shelly Flood wasn't built for that. It only reports whether water has reached one point — no level, no pump cycles. And in a power outage, the push notification goes down with the router. Drainbee was designed specifically for this use case — with a submersible probe, level and pump cycle history, and app alerts, even on power outage and WiFi loss.
But for the pump sump, Shelly Flood wasn't built for that. It only reports whether water has reached one point — no level, no pump cycles. And in a power outage, the push notification goes down with the router. Drainbee was designed specifically for this use case — with a submersible probe, level and pump cycle history, and app alerts, even on power outage and WiFi loss.
Frequently asked questions
Can I place the Shelly Flood in a pump sump?
Not the device itself: it's only rated IP44 (splash-proof) and is mounted on the wall. You can, however, hang the Gen4's sensor cable into the shaft. It then alerts as soon as the water reaches that height — a single trigger point, not a measurement. It won't show you how high the water is or how often the pump runs. Drainbee's probe continuously measures the water level in the shaft to within ±1 cm.
Isn't Drainbee much more expensive than the Shelly Flood?
Yes — Shelly Flood Gen4 costs €34.90, Drainbee €298 (one-time, no subscription). The difference reflects the use case: Shelly Flood reports whether water touches the sensor. Drainbee measures the water level in the pump sump, shows pump cycles and inflow in its history, and alerts you in the app — even on power outage and WiFi loss. For the pump sump, a wet/dry sensor simply isn't enough.
What happens to the Shelly Flood during a power outage?
The Shelly Flood runs on batteries, and its buzzer keeps beeping when it detects water. But it needs WiFi (or a Zigbee/Matter hub) to send push notifications. When the power goes out, your router is usually offline too — so no notification reaches you, and it doesn't report the power cut itself. Drainbee has no battery and stops reporting during a power cut. The Drainbee cloud notices the device has gone offline and alerts you in the app.
Can I use Shelly Flood and Drainbee together?
Yes — and it's actually an excellent combination. Shelly Flood for leak detection in the kitchen, bathroom, and laundry room. Drainbee for monitoring the pump sump. Both systems work independently and complement each other perfectly.