A deposit return scheme is a simple idea. A small refundable amount is added to the price of a bottle, and returned when the empty bottle comes back. It turns an empty container from rubbish into something worth carrying back.
The results are hard to argue with. Countries running deposit schemes recover most of their containers, against a fraction of that where returns are voluntary. In Tamil Nadu, a pilot at selected outlets saw around 80% of empty bottles brought back once machines made returning them easy.
What makes the difference is not the size of the deposit but how easy it is to claim. A customer who has to fill in a form, wait, or come back another day will not bother. A customer who scans a code and watches the money arrive on their phone before leaving the counter will bring the next bottle too.
That is the part we work on: the few seconds between handing over a bottle and the money arriving.