Our water at home is supplied by way of rainwater off the roof of the house. We have about 55000 Litres (~14500 Gallons) of storage capacity but a long dry summer sees the levels drop considerably.

I decided it was time to add a water meter into the circuit to be able to monitor our water usage.

I picked up an Elster S100 water meter complete with an electronic Pulse output.

The meter outputs one pulse per Litre of water. It’s only a two wire output so it appears to be a simple switched output such as that from a reed switch, but I’ll need to check before committing to any specific circuit design.

I’ll Probably use an Atmel AVR Microcontroller to count the pulses. The AVR will be setup as an SPI Slave to talk to a Raspberry Pi. I should have a better idea how best to implement it soon.