How can water be sold and purchased through a prepayment system using a smartphone?

ADD Grup implements technical solutions based on STS standards that allow consumers to purchase water through a prepayment system.

To use water, the consumer acquires digital tokens, which are transferred to the water meter via an app on their smartphone. Once the tokens are depleted, the valve shuts off the water supply to the consumer. Such solutions are mainly used by utility companies in developing countries to mitigate the risk of non-payment for resources.