What a float switch does well
The float switch has earned its place — it's the proven standard in pump control:
- Decades of track record: Simple, robust principle. No electronics, no software, no updates needed.
- Direct pump control: Switches the pump on and off mechanically — no power needed for the switch itself.
- Affordable: Many submersible pumps come with one built in. Bought separately, basic float switches start at around €10 in shops, while branded ones cost over €100 depending on cable length (list price).
- Independent: Works without WiFi, without cloud, without an app. Purely mechanical.
- Little maintenance: It's enough to lift the float now and then and check that it moves freely and the pump starts.
- Can be extended into an alarm: A second float on an alarm unit (e.g. Jung Pumpen AG3) warns of high water in the sump with a loud buzzer. It has a potential-free contact for remote signalling and, with the optional rechargeable battery, keeps working for about 3 hours without mains power, according to the manufacturer.
Why a float switch alone isn't enough
The problem isn't that the float switch is bad — the problem is that it's a single point of failure with no feedback:
- Can jam: Deposits, corrosion, or tight spaces in the pump sump — the float can get stuck. Pump manufacturers such as Grundfos explicitly list a float that can't move freely or is set incorrectly as a fault cause: the pump then won't start, or runs without moving any water.
- No alert on its own: The pump's control float reports nothing — no status message, no remote monitoring. An alarm unit with a second float only beeps on site. Getting the alert to your phone takes an add-on wired to its potential-free contact.
- No history: You can't see when or how often the pump ran. Many pumps sit idle on most days — so a stuck float often only shows up at the next heavy rain.
- No protection during power outages: When power fails, the pump stops — and the float switch can't inform you about it.
Feature comparison
| Feature | Drainbee | Float switch |
|---|---|---|
| Direct pump control | ||
| Independent water level measurement | ||
| Level alarm on your phone (e.g. when the float sticks) | ||
| Call-style alarm in the app | ||
| Phone alert during power outage | ||
| Works without WiFi and internet | ||
| Level and pump cycle history | ||
| Remote access via app | ||
| Loud on-site buzzer (with alarm unit) | ||
| Price | 298 € | ≥ 10 € |
When do you need which?
The answer isn't "float switch or sensor" — the answer is "both". They serve different roles:
Float switch = control
- Switches the pump on and off at a set water level
- Works mechanically, no power needed for the switch itself
- Already integrated in most pumps
Drainbee sensor = monitoring
- Measures the water level independently of the float switch
- Alerts you when the level rises above your threshold (= float stuck or pump defective)
- Alerts you in the app — even on power outage and WiFi loss
- Shows level, pump cycles and inflow over time, so you can see whether the pump runs at all
Drainbee is the second opinion — independent from the primary control mechanism. Like a smoke detector that checks whether the fire extinguisher still works.
Verdict
The float switch and Drainbee aren't competitors — they're a team. The float switch controls the pump. Drainbee monitors whether the control is working. That's the crucial difference: the float switch can't tell you it has failed. Drainbee notices it from the rising level.
Relying solely on a float switch means running a system without feedback. A jammed float, a defective pump, or a power outage — all of these go unnoticed until the damage is done. An alarm unit only helps if someone hears the buzzer. Drainbee closes this gap: independent measurement and app alerts — even on power outage and WiFi loss. For €298 you get the second safety layer that your float switch alone cannot provide.
Relying solely on a float switch means running a system without feedback. A jammed float, a defective pump, or a power outage — all of these go unnoticed until the damage is done. An alarm unit only helps if someone hears the buzzer. Drainbee closes this gap: independent measurement and app alerts — even on power outage and WiFi loss. For €298 you get the second safety layer that your float switch alone cannot provide.
Frequently asked questions
Does Drainbee replace my float switch?
No. Drainbee is a monitoring system, not a pump control switch. Your float switch continues to control the pump. Drainbee is installed alongside it and measures the level independently — if it rises too high because the float switch isn't doing its job, you get an alert. Both systems work in parallel — the float switch controls, Drainbee monitors.
How does Drainbee detect that my float switch is jammed?
Drainbee measures the water level independently of the float switch. In the app you set an alarm threshold, ideally just above the pump's switch-on point. If the level rises above it, Drainbee alerts you — whether the float is stuck or the pump is defective. The cycle history also shows you when the pump last ran. If the power fails, the device stops reporting and the Drainbee cloud alerts you separately.
What happens during a power outage?
During a power outage, your pump stops — that's unavoidable. Drainbee has no battery and goes down too. But the Drainbee cloud notices that the device has stopped reporting and alerts you in the app — so you know your basement is unprotected. A float switch alone can't warn you. An alarm unit with the optional rechargeable battery keeps sounding an on-site alarm for about 3 hours without mains power if the water rises, according to the manufacturer.
How often do float switches actually jam?
Manufacturers don't publish reliable failure statistics. But they explicitly list a float that can't move freely or is set incorrectly as a fault cause, and require enough space in the sump for it to move freely. Deposits, limescale, corrosion and tight installation spaces increase the risk over the years. The long idle periods are what make it tricky: in our analysis of 8 Drainbee pump sumps (March–October 2026), the pump didn't run at all on 62 % of days, while on its busiest day it typically ran about seven times as often as on a normal pump day. So a stuck float often only shows up when it matters. That's why you should lift it regularly and check that the pump starts.
Do I need technical knowledge for installation?
No. The Drainbee probe is simply lowered into the pump sump — next to the existing float switch. There's no modification to the existing pump control. Setup via the app takes just a few minutes. Your float switch stays as it is.
Sources
- Wilo: Schwimmerschalter WA65 mit 5 m Kabel – Produktseite (2026) (opens in a new tab)
- Grundfos: Unilift KP 150, KP 250, KP 350 – Installation and operating instructions (2022) (opens in a new tab)
- Jung Pumpen: Alarmgeber – Produktübersicht (2026) (opens in a new tab)
- Jung Pumpen: Alarmgeber AG/AW – Betriebsanleitung (2023) (opens in a new tab)