The nightmare is over for Bukit Batok residents with pest controllers declaring the area rat free after killing more than 300 rats over two weeks.
There was no physical evidence of rats in the area by the third week of the operation, based on human assessments in the day and infrared camera recordings at night, said Mr Bernard Chan, manager of Star Pest Control.
Mr Chan said that his team concluded the extermination process yesterday.
The rat infestation first came to light last month after Bukit Batok resident Ryan Keith Smith, 33, took videos and pictures of the rodents and posted them online.
Pest controllers spent the first part of the extermination process attacking the rodents' nests and burrows.
More than 230 rats were killed in the first seven days by about 30 pest controllers who scoured the hilly area, about the size of a football field.
The next two weeks were spent monitoring and locating the survivors to ensure that they do not migrate to other areas. This involved the use of infrared cameras to monitor rat activity at night.
Pest controllers also conducted surveillance with binoculars from vantage points such as multi-storey carparks. An average of 10 rats were killed in the second week but, by the third week, the rats had disappeared.
"Shelter, water and food are needed for rats' survival, so if you can break the chain, you can break the infestation," said Mr Chan, who has been in the business of controlling pests for the past 11 years.
"This Bukit Batok incident isn't normal in Singapore, but it was still controllable. I've seen worse."
The Housing Board, which has been working with the pest controllers on the issue, said that it would continue to monitor the area regularly to minimise the recurrence of rodent infestations.
Rodents will proliferate if food sources are available, added an HDB spokesman.
"For anti-rodent efforts to remain effective, we wish to remind the public not to leave food for strays."