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Western Wastewater Treatment Plant

At the Western Treatment Plant, sewage travels through a series of screens, tanks, bioreactors, clarifiers and ultraviolet treatments before being discharged as liquid into Cook Strait in the vicinity of the Karori Stream Mouth.

The Western Treatment Plant was granted new consents on 28 July 2010. These consents will continue for 25 years (expire 28 July 2035).

In general, the consents allow Wellington City Council to:

  • discharge of treated and partially treated effluent through an existing outfall,
  • to discharge mixed disinfected, treated and milli-screened wastewater during and/or immediately after heavy rainfall,
  • the discharge of contaminants to the air,
  • and permission to occupy the coastal marine area with an outfall structure.

Resource consents

Resource consent reports

Plant performance


Current Status: 
Compliant 
Period: July 2025

Commentary:
The plant is compliant for effluent quality.

​Discharges:
There were two consented wet weather discharges to the Karori Stream on 4 and 12 July. 

Odour complaints:
No odour complaints in July.

Items of significance:

There are no items of significance currently.

​Read the full July 2025 Western wastewater treatment plant monthly performance report

Community Liaison Group Meetings