Sewer chief says they have fixed the stink that has wafted over Hillsborough, Auckland for weeks

The source of the stink in Hillsborough, Auckland was a broken flap on a sewer siphon at Hoskins Ave, by the red pin. Map / Google

Sewer managers say they have fixed the pipe that has caused a stink to waft over Hillsborough in Auckland for weeks.

At first the hot, dry summer was blamed by Watercare Services.

The stench was traced to a "siphon" in Hoskins Ave where a sewer dips down under the Manukau Harbour before rising on the far side in Māngere on its route to the wastewater treatment plant.

A siphon needs a vent. The foul air that comes out is put through a biological filter containing bark, scoria and earth. The filter media must be damp to work properly and relies on rainfall plus irrigation. Insufficient dampness was thought to be the problem when the Herald inquired yesterday.

Today, however, a mechanical flap has been blamed.

"In recent weeks, some residents in Hillsborough have noticed wastewater odours," said Watercare's head of service delivery, Simon Porter.

"Investigations have been ongoing and this afternoon, a broken mechanical flap on a wastewater siphon in Hoskins Avenue was discovered. It was repaired immediately and we're confident that this will put an end to any odour issues.

"We'd like to apologise to any members of the community who were inconvenienced by this fault."