The water meter is at the street rather than in his ... which relies on detecting the varying magnetic field due to the spinny-bits inside the flowmeter and cleaning up the signal with the Arduino ...

A magnetic flow meter relies on Faraday's Law of Induction to measure the flow of a fluid. Magnets outside the pipe create a magnetic field. Electrodes are located perpendicular to the magnets.

Using a magnetometer placed close to the meter, the device can sense the magnetic field created as water flows through the meter’s internal sensors. The magnetic field changes in a non-obvious ...