Police declared a major incident in Lewisham as Lee High Road as the bus became stuck and those on board had to be rescued.
Meanwhile a number of residents were left without water and some even had to be moved to temporary shelter.
Sandbags were also distributed to residents and businesses in the area.
The London Fire Brigade said as many as 3,000 home had their water supply interrupted.
A Thames Water spokesman said: “We’re very sorry to customers in SE3 experiencing problems with their water supply as a result of our burst water pipe on Lee High Road. We have a large team on site working hard to get things back to normal for those affected and we hope to have supplies restored by the end of the day.
“We’re arranging for bottled water to be brought to the area and details of collection points will be available on our website shortly. We’ve also contacted vulnerable customers.
“We’ll begin the repair to the pipe as soon as we can.”
Lee High Road remains closed.