A water meter should keep working when the network does not

Many connected devices fail in the exact places they are supposed to help, because they assume a live connection at the tap. A prepaid meter has a different job. It must recognise a purchase, protect the credit, and control the valve on its own.

With the A-Z meter, the customer buys water where there is internet, then carries a secure token to the meter. The phone can pass that token over the meter’s own Wi-Fi, or the customer can type the numeric token on the keypad. The meter checks the token locally.

Water keeps flowing from stored credit even if the neighbourhood network is down. Internet is for buying. The meter is for measuring and control.