Work has begun to replace ageing water mains in a Hampstead street after a major water leak left a gaping void under tarmac last October.

Ham & High: Thames Water said the void under the road was likely caused by leaking water moving earthThames Water said the void under the road was likely caused by leaking water moving earth (Image: Archant)

Thames Water today began a 12-week programme of work to replace pipes in Flask Walk, during which time the road will be closed to traffic.

Flask Walk was urgently closed last October when engineers investigating a burst pipe discovered a gaping chasm under the road.

Thames Water said it was likely the gap was caused by the leaking four-inch pipe shifting earth.

The incident led to calls for the area’s ageing Victorian pipes to be replaced after a spate of leaks.

Work was not scheduled to take place until 2019, but Thames Water contractors will now remove the old cast iron water mains, which are prone to leaks, and replace them with more durable plastic pipes.

The road closure will also include the suspension of some parking areas in Flask Walk and residents have been contacted with details of alternative arrangements.

Work will also take place in Back Lane and Gardnor Road, but they will not be closed to traffic.

Mark Taylor, Thames Water’s head of programme delivery, said: “We appreciate just how much disruption was caused when the water main burst in Flask Walk back in October last year, so this replacement work will hopefully combat further problems in the future.”