The Council has obligations under specific acts and bylaws to safeguard the health of the community and the environment.

Wastewater regulation

The main regulations governing the collection, treatment, and discharge of wastewater are:

  • Resource Management Act 1991
  • Local Government Acts 1974 and 2002
  • Water Supply, Wastewater and Stormwater Bylaw 2014
  • Building Act 1991
  • Trade Waste Bylaw 2015.

Monitoring of levels of certain chemicals takes place. In some instances particular substances are either prohibited, e.g. asbestos or organochlorine pesticides, or are allowed into the sewer only in limited quantities, as is the case with chromium, nickel and cadmium.

Because of the need to provide for such a valuable asset, the Christchurch City Council has an asset management plan in place to manage the wastewater pipeline assets. The plan provides a strategy to meet the demands of expected city growth well into the 21st century to maintain the pipe assets and to upgrade the level of service where appropriate.

Pipe maintenance

One advantage that the Christchurch sewage system has is the high quality of its pipe infrastructure, due to the high level of asset investment in past years. Without such a high standard of early piping, the city may well have run into difficulties as the city has a high water table and draws its drinking water from underground aquifers. Most pipes laid in the city are below groundwater and pipe imperfections could cause groundwater infiltration as well as overflows.

Existing pipelines under the city are a mixture of old brick, ceramic, cast iron, newer concrete, and plastic. For optimum performance the pipes need to be regularly maintained and upgraded where necessary. The pipes have an average economic life of at least 90 years, with older pipes being renewed as needed. Until recently, the only way of knowing the condition of underground pipes was when they blocked or failed, leaving a depression in the road. With the introduction of closed circuit television monitoring, the condition of the pipes can be regularly checked to prioritise their renewal.