Work's starting to have more than 500 houses on Auckland's North Shore permanently back on the wastewater network

Over the next six months, Watercare will replace nine temporary bypasses, that have been in place since last year's Anniversary Weekend flooding.

Asset upgrades and renewals general manager Suzanne Lucas says the first three months will be focused on reconnecting roads in Castor Bay, before moving to Bayview.

She says they'll install the new pipes using horizontal directional drilling - to protect them from future slips and flooding.

Work's expected to be finished by the end of January.