Sewage Treatment Plants

Moa Point before sewage treatment

There are three sewage treatment plants in Wellington - Moa Point, the Western Treatment Plant (Karori) and the Southern Landfill Sludge Treatment Plant.

The Council also has a 27.6% share in the Porirua Treatment Plant which treats sewage from Wellington's northern suburbs.

The Council contracts United Water International to operate both Moa Point and the Western Treatment Plant.

Waste Treatment Process

Moa Point after sewage treatment

At the treatment plant, sewage travels through a series of screens, tanks, bioreactors, clarifiers and ultra violet treatments before being discharged as liquid into Cook Strait.

• Non-organic - large, non-organic materials such as toilet paper are first removed using screens. This rubbish is washed and compressed and sent to the Southern Landfill for disposal.
• Solid sewage (sludge) - as sewage travels through sedimentation tanks, the majority of solids are removed. This sludge is taken to the Southern Landfill Sludge Treatment Plant where it is de-watered (water removed from solids). De-watered solids are combined with green waste to make high quality compost sold commercially by Living Earth.
• Effluent sewage (flowing) - a series of tanks and bioreactors use a combination of sedimentation and bacteria to decompose almost 70% of effluent material. Remaining liquid effluent is exposed to ultra violet light to destroy any harmful bacteria. The treated liquid is finally discharged into Cook Strait.

Department Details:
Capacity (Wellington Water Management Ltd)