Many Singaporeans enjoy hawker fare, but it seems that few want to clean up after themselves. Just one in five diners returns his tray after a meal at a hawker centre, observers say.

But bad tray etiquette may soon start to hit customers in the pocket.

A system of charging them a deposit that will be forfeited if they do not return their food trays could be rolled out at up to 25 hawker centres, as part of a government push to boost productivity.

But an additional cost, even in the form of a returnable deposit, will not be welcomed by patrons and those hoping for a more sustainable way of encouraging social change. However, the dismal rate at which trays are returned shows that Singaporeans need a greater push to do the right thing.

Since last December, deposits of 50 cents and $1 per tray taken have been levied at Marsiling Mall Hawker Centre and Bukit Merah Hawker Centre respectively. However, patrons and hawkers at both said they noticed people either not taking trays as a result, or taking and returning trays but leaving their used crockery behind.

Such teething problems are to be expected. But that is not to say the system will not be successful in the long term. Food hall Timbre+ in one-north charges patrons a refundable $1 deposit for each tray, but has a return rate of 97 per cent.

Other successful tray return schemes do not offer discounts or implement tray deposits.

The hawker centre at Khoo Teck Puat Hospital, for example, has upped its tray return rate from 20 per cent to 70 per cent through examples set by its management.

Design is also important - the hospital's hawker centre has centrally located tray return areas that are easily accessible. This model may be difficult to replicate in existing public hawker centres.

So while tray deposits may not be the most welcome of measures, perhaps it is what is needed to get people thinking about what gracious behaviour is.