Counter of circuit close events on GPIO pins, using TI MSP430 microcontroller (on the LaunchPad MSP430G2) and TI CC2541 Bluetooth Low Energy (Bluetooth Smart) module with Emmoco firmware, based on Emmoco example code.
msp430 directory contains microcontroller code for the sensor.
Connect the wires from the water meters to the ground pin and
pins P1.4 and P1.5 for cold and hot meters respectively. Internal
pullup is used. To save power, modify the code to disable internal
pullup, and use external pullup resistor of 5 - 10 MOhm. And
probably disable VCLK in sleep mode.
linux directory contains the code to be run on Linux host. It
uses BlueZ infrastructure. You will need a BT 4.0 compatible
hardware connected to the host.