More public education and stimulating policies should be introduced to boost classification of waste, which will ensure better recycling and environment protection after a recent survey found that most local residents just dump their rubbish without classifying it.

The survey conducted by the Shanghai Statistics Bureau found that only about 20 percent of residents classify their rubbish before throwing it, while 37 percent just pick out harmful items, like batteries, and lump the rest together and 40 percent of residents never classify their rubbish.

By last year, the Shanghai Greenery and Public Sanitation Bureau had installed trash bins with different colors in 3,738 residential communities in a bid to promote rubbish classification.

Yellow is for glass and glass-made items, blue for recyclable waste like paper and plastic items, orange is for harmful waste like batteries and overdue medicines and green is for other waste like kitchen waste and children's napkins.

"I know different trash cans mean collection of different waste but I still don't understand how to sort household waste properly. It sounds like big trouble and people around me never do it as well," said Wang Caidi, a middle-aged woman living at a residential community on Weihai Road in Jing'an District.

Wang is a typical example.

Officials said most people think it is troublesome to classify rubbish and put them into relevant bins.

The bureau said it chose the 3,000-odd residential complexes because they are middle and high-end neighborhoods but it has not been smooth sailing.

Not classifying rubbish means Shanghai has to deal with a mountain of waste that cannot be recycled.

Shanghai generated 7.1 million tons of life waste last year, 4.7 percent more than in 2008. Most waste was simply buried unsorted, imposing pressure on land sources and the environment.

Local officials said they have considered following the lead of some developed countries by charging rubbish fees from those who fail to classify their trash, but the topic has been under discussion for years without results.

However, they said proper guidance and education and incentives may be more practical than charging new fees.

Some high-end neighborhood committees have cooperated with district governments in giving small gifts to residents who separate recyclable waste and harmful trash regularly.