The Diamond Harbour wastewater treatment plant treats wastewater from Diamond Harbour, Church Bay and Charteris Bay. It is accessed off Otamuhua Lane and is located below Koromiko Crescent.


Sewage receives primary and secondary treatment within the plant followed by ultra-violet (UV) disinfection before being discharged through an outfall pipeline into the harbour. Sludge is regularly removed and transported to the Christchurch Wastewater Treatment Plant.

Resource consent

The main resource consent for discharge to the harbour (CRC101835) expires in 2021. The Council has a programme of works planned for completion in 2022, which will see this plant decommissioned, with all of the raw wastewater from Lyttelton Harbour being pumped directly to the Christchurch Wastewater Treatment Plant. For more information please see Lyttelton Harbour wastewater scheme.

Consent monitoring

Resource consent CRC101835 sets out requirements for monitoring treated wastewater and the area receiving the discharge (receiving environment). Samples are taken and analysed on a regular basis. The volume of wastewater leaving the plant is recorded continuously. Together these provide an indication of how the plant is performing and whether there are any potential adverse effects of the discharge on human health or the environment.

Monitoring data is provided in the tables and graphs linked to below:

Annual monitoring reports