It was Oct 1, 1968. More than 1,500 community leaders had filed into the Singapore Conference Hall and were about to hear an announcement that would change the face of Singapore.
A few months earlier, the Government had formed a national committee to tackle the country's cleanliness and littering problem. The group ran the gamut from representatives from the ministries of health, education and culture, to non-governmental groups. Prime Minister Lee Kuan Yew took the stage to launch the campaign's next step - to get ordinary Singaporeans on board.
"Everyone can see the point of a new home, clean kitchen, clean food and healthy children. But responsibility stops too often at the doorstep," he said.
The inaugural, month-long Keep Singapore Clean campaign, as it was called, was a blitz across the country, with posters and banners in Singapore's four official languages put up in shops, restaurants, offices, factories, community centres, bus shelters and public notice boards. Mini-posters, leaflets, pamphlets and car-bumper stickers were handed out, and even postal items and cinema tickets bore the Keep Singapore Clean slogan.
At the campaign's closing ceremony on Nov 1, then Minister for Health Chua Sian Chin said "there has been a visible transformation of the face of Singapore".
• Oct 1, 1968: Singapore launches the month-long Keep Singapore Clean campaign, one of its first national campaigns as an independent nation.
• 1970s and 80s: More related campaigns, including Keep Your Factory Clean and Keep The Toilet Clean.
• 1990: Launch of Clean and Green Week that takes place every November.
• 2007: That becomes Clean and Green Singapore, to get people to care for the environment all year round. The new campaign also promotes energ
• 2015: The Public Hygiene Council, Keep Singapore Beautiful Movement and Singapore Kindness Movement organise OperationWeClean Up!, a first-of-its-kind, one-day event to pick uplitter across the country. More than 7,000kg of rubbish are collected.
Although there were some bad areas where littering had continued, most people had done their spring-cleaning, there were litter boxes everywhere, and there was even "an air of cleanliness and confidence".
Mr Chua added: "We shall not lack the zeal and persistence and, if necessary, the ruthlessness, in this long and arduous war against filth and squalor."
The Keep Singapore Clean campaign became an annual event, and was joined by several other major projects to turn the Republic into a clean and green city.
Retiree T. K. Pillai, 86, who joined the then Sewerage Department in 1971, said work to develop a comprehensive sewerage system started in the 1960s and accelerated in the 1970s. This was to collect waste and prevent it from entering water bodies. "We had to lay sewers all over the island to connect new public housing and existing homes that were not served, to the sewerage system," he said.
By January 1987, Singapore had bid farewell to its night-soil bucket system, where workers went on daily rounds to empty and clean buckets of human waste. The then Ministry of the Environment spent $1.6 billion to develop the new sewerage system.
Mr Pillai said: "Without (such a) system to handle the waste, Singapore would not be able to have such a large population on such a small island without constant epidemics."
In 1987, Mr Lee awarded him and nine other people gold medals for their leadership in cleaning up the Singapore River and Kallang Basin.
National water agency PUB's chairman, Mr Tan Gee Paw, 71, drafted the ambitious 10-year plan to clean up the Singapore River in 1977, when he was the Ministry of the Environment's director of environmental engineering.
He said: "The water was dirty and public health so poor... There were infectious diseases, rodents and cockroaches, and you couldn't even be sure the food you were eating was clean... The clean-up required a strong-willed government. Now, we have clean water, clean air, good public and environmental health - that was the pathway to success."