Managing stormwater

The Council manages the network that collects, transports and disposes of stormwater. We work hard to reduce the risks of flooding and pollution.

Stormwater is discharged - untreated - into Wellington harbours and streams. That's why it's important to keep it as clean as possible. The Council commits resources each year to improving water quality in the inner harbour and along the south coast.

Stormwater network quick facts

  • 650km of pipes
  • 20km of tunnels
  • 51 years average age of pipes
  • $639 million value
  • 79 million cubic litres per year
  • 530 stormwater intakes
  • 12,500 road sumps

Policy objectives

The Council's key objectives are to:

  • Eliminate cross-connections
    Cross-connections occur when a property's sewerage is illegally connected to the stormwater network. Because stormwater ends up in the harbour, this can be a major source of pollution. The Council actively works to locate and remove cross-connections.
  • Reduce sewage pollution
    Pipe damage and other problems with the sewerage network can pollute the stormwater network. The Council routinely collects stormwater samples for testing. If there is any sewage contamination, we investigate its source and make necessary repairs.
  • Increase sewage storage
    The Council has agreed to a programme to provide more storage at sewerage pump stations. This will give more time to fix any problems before raw sewage overflows into the stormwater network.
  • Carry out Catchment Management Plans (CMPs)
    A catchment is an area where water, particularly rainwater, collects when it follows its path downhill. CMPs help us manage stormwater, develop strategies to improve the network and address water quality issues.

A typical CMP helps protect against flooding by recommending solutions for:

  • pipes or channels that are too small
  • areas where a stormwater system is needed
  • flood pollution
  • other issues, such as construction, that may impact on flood protection.

Policies - Integrated Catchment Management Plan