Two burst water pipes in as many days have placed the nation's pipe network in the spotlight again, coming after other incidents of burst or leaking conduits earlier in the month.

In the latest incident, a burst pipe in Upper Serangoon Road yesterday made for a sodden journey to school and work, though it did not disrupt the water supply, said national water agency PUB.

The cause of the leak is still being investigated.

The burst pipe, which led to water steadily streaming from cracks in the ground, was discovered at around 2am, and service crew and contractors were sent there immediately, PUB said.

At about 8.30am, two out of three lanes of the road were closed, and the agency advised motorists to consider alternative routes.

On Sunday, a burst pipe caused a 30-minute disruption to the water supply of residents living in Choa Chu Kang Avenue 2.

Several weeks ago, corrosion caused two water pipes in Bukit Batok to burst, while a small leak in a water pipe at the junction of Tanjong Katong Road and Boscombe Road that occurred around the same time had to be repaired.

Following the incidents in Bukit Batok, PUB had said it was looking to speed up a project to replace ageing water pipes islandwide.

Because of yesterday's leak, SBS Transit had to divert seven of its bus services for about 1-1/2 hours.

But by 8pm last night, only a 10m stretch of one lane near the junction of Upper Serangoon Road and Wolskel Road remained closed for repairs.

Chiropractor Will Kalla, 41, who was waiting about 150m away from the affected junction, said: "I knew something was wrong because there were no cars on the road. All I could see in the distance was just water and police cars and some PUB staff."

He was waiting with his three-year-old daughter for her school bus to take her to Marymount Kindergarten. The bus usually arrives at 7.20am.

"We waited for 15 minutes before my wife called the driver. He said he could not get to where we were, so we walked about 500m through the housing estate to get to Bartley Road where he was waiting."

Mr James Wee, 34, whose son attends a nearby kindergarten, said: "Usually, I drop him off in the morning. But today, I had to walk with him here because it would take longer by car."

Mr Wee, who works in the IT industry, said he lives nearby.

A check on the Singapore Examinations and Assessment Board website showed there were two O-level combined humanities written examinations at 8am yesterday.

The Straits Times understands that, as with any other transit-related delay, affected students would have been given a time allowance.

They also have the option of going to a nearby examination centre to sit the exam.

Meanwhile, repairs works were still ongoing yesterday to fix the leak in Choa Chu Kang, which caused some households to receive brownish water.

A Chua Chu Kang Town Council spokesman said this was due to natural sediments in the water tank. "Flushing of the water tank and pipes has since been conducted," he added.

PUB said the leak was unrelated to the incidents in Bukit Batok.

• Additional reporting by Fabian Koh and Charmaine Ng