SUPERTOOL Floating Switch L250mm, Stainless Steel Water Level Sensor, Vertical Float Switch used in Electricity, Drainage, Level Control and Alarm

So far so good. Couples with a NodeMCU (ESP8266) and Home Assistant for notifications if the fish pond water level is low.

This has been mounted in the vertical position, in water. It failed to operate within the few operations after install.

I got this floatswitch to monitor the water level in my fish pond. When my box filter clogs up the pond water from the filter pump overflows into the garden instead of being returned to the pond, resulting in the pond being emptied if I'm not around. Now when the pond water level drops by 70mm, the electricity to the filter pump is disconnected thereby saving a disaster.

I use this device to notify me if the level of my pond falls dangerously low. Perfect for my needs. it just provides a simple active/inactive result. Good little unit (the wires are a not very long).

I used this to measure the amount of water in the on board tank in our caravan. Works great and accurate.

Switches erratically and in no relation to where the float is. Cannot be trusted for use where water draining/pumping is required.

I've installed this as an early warning system for my water heater levels (as it just completely shuts off when it gets too low) with a microcontroller and it has worked perfectly. Its a nice little binary sensor - You may have an issue if its not the right size, but its nice and easy to use