There will be a flat 20p deposit on all eligible plastic and metal drinks containers. These deposits can be retrieved by returning containers to collection points at supermarkets.
The Welsh government want this to be devolved to them: https://exchangeforchange.co.uk/news/welsh-government-decision-on-exchange-for-changes-dmo-application/


Let me tell you exactly how this will play out. No one will return the bottles and your public rubbish bins will be opened and their contents spilled on the ground, as the indigent dig through it looking for the bottles. No they will not clean up after themselves. Yes, rubbish will get every where. And then your bins start to have preachy stickers about turning things in to avoid the crackcoons from digging through the rubbish.
Source: exactly what happens in metropolitan areas in NL