Contractors at Arch Hill Scenic Reserve in Grey Lynn will work on the burst pipe.

Auckland city residents have been asked to reduce water consumption after a main pipe burst.

"Gross" smelling water marred with silt was trickling down Ivanhoe Rd just before noon on Monday, a Stuff reporter on the scene said.

The 550mm diameter watermain burst about 6.45am, flooding the Arch Hill Scenic Reserve in Grey Lynn.

Chris McKeen/Stuff After taking over a forestry right in Auckland's Hūnua Ranges, Watercare is aiming for 3.5m native trees to be planted around its Upper Mangatawhiri Dam.

Eight Watercare vehicles, including two with tankers on the back, were at the scene.

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"No water outages are expected but residents over a wide area of central-west Auckland may notice reduced water pressure, whilst the repairs are underway," Watercare said in a statement.

RYAN ANDERSON/STUFF At least two Watercare tankers were on site.

A resident on Ivanhoe Rd said a dog walker approached them about 9:30am asking to council about a burst water main up the road, a Stuff reporter said.

The resident phoned police to make sure someone got to the main quickly as the water was already running quite far down the street.

The broken section of pipe was isolated just after noon. Water had stopped flowing through the park and repairs will begin shortly, Watercare said.

The pipe will take up to 24 hours to repair.

"We ask residents to please reduce water consumption whilst this emergency work takes place."

Traffic management was in place along nearby roads, including Tay Street, Great North Rd and Ivanhoe Rd.