Wellington Water is still working to repair a broken water main which has left a swathe of Porirua residents with low water pressure – or no water at all.

The pipe burst on Tuesday morning and water tankers were "urgently" deployed to the area to assist properties without. The burst also meant residents of neighbouring Titahi Bay were urged to conserve water.

A spokesperson for Wellington Water said the burst main on Parumoana St could impact the water for nearby residents for up to five hours. By Tuesday afternoon, crews were still excavating the burst pipe.

Ian Dennis, Wellington Water's customer experience manager, told the Herald crews have started to excavate the area for the repair and hope to have it completed by 2pm.

"This may change once the full extent of the burst is determined."

However an update at 2pm revealed the work was more extensive than anticipated.

"The team has exposed 4m of the broken 150mm pipe. Unfortunately the pipe has split past the collar and a further 2-3m will need to be excavated.

"Customers in the affected zone will continue to either have low flow or no supply until the repair is completed."

Footage posted to a local community Facebook page showed the flooding in full flow around 7am.

The video showed much of the car park underwater with water spilling out from under the ground.

Wellington Water said on social media although crews are on-site, work can't start until traffic management is in place, and further updates will be provided once work has begun.