A flow meter can also be connected to the sensor input.
In principle, all two-wire flow meters can be connected. If an additional 5VDC is required, this can be tapped at the VIN connection.
The whole thing then works like this:
- Connecting the flow meter to the OpenSprinkler.
- Start the app and go to “Edit options” / “Weather and sensors”.
- Set “Sensor Type” to “Flow”.
- Set “flow rate”. This is the value of the flow meter pulse. You can find out how much a pulse is from the manufacturer of your flow meter.
- complete.
- The flow rate for the past irrigations then appears in the log (“View logs” menu).
More details here:
https://OpenSprinkler.com/forums/topic/flow-meter-wiring/
(in English)

Hello, can you supply/offer or recommend a flow meter? That would be the icing on the cake.
Best regards
Andreas Groth
Just google impulse water meter. Preferably one with 1L/pulse