The company will add 10p to the cost of its plastic bottles which will be refunded to customers when they bring the bottle back.
It said it hopes the initial trial will go ahead in Brighton in April.
Clive schlee, CEO of Pret a Manger said: “The idea is that we would add 10p to all plastic bottles and return 10p for each Pret bottle given back to our teams to recycle.
“The aim is to understand how many bottles are returned and to see if it encourages more customers to opt for a reusable bottle.
“We will of course reinvest any unclaimed deposits in future sustainability work.
“It will take time to eliminate unnecessary plastic, but I hope this sort of initiative will bring that day forward by drawing attention to the issue and stimulating new ideas.”
The company said it chose Brighton as it has three busy shops there and was aware that the local people are “highly attuned to the environment”.
If successful the company is open to extending the scheme across the country in autumn.
In 2016 it was estimated that half the plastic bottles sold were recycled, Pret said it hopes to increase this number.