Stormwater risks, requirements and responsibilities

Stormwater and development

If you are doing any sort of development, one of the factors you need to consider is stormwater.

Inadequate stormwater facilities place a constraint on development. For this reason, developers need to show how they will deal with stormwater run-off.

In urban environments, stormwater can create three major issues:

• flooding, due to the volume of water
• stream erosion, due to the increased speed of the water
• water pollution, due to potential contaminants the water is carrying.

Builders need to place barriers like silt fences and filter socks on and around sites where they work so that dirty water containing earth and sediment doesn't wash off the site and into drains.

How we manage stormwater

The stormwater network is crucial for managing the overflow of water on properties and streets when it rains. Managing stormwater ensures flooding and associated environmental problems are reduced as much as possible.

We map overland flow paths of rainwater, including rare heavy rainstorms. You can find out if your property is in an overland flow path by using our GeoMaps viewer or getting a Land Information Memorandum (LIM).

Stormwater and the Auckland Unitary Plan (AUP)

AUP has adopted an Integrated Stormwater Management approach to maintain good water quality and improve it where it is degraded.

The AUP includes rules on:

• the diversion and discharge of stormwater
• the quality of stormwater
• the quantity (flow) of the stormwater.

• the size of impervious area on your site
• where the stormwater is being directed to
• if the stormwater is coming from a high-contaminant generating car park or a high use road
• if your site is located in a Stormwater Management Area.

Auckland region Network Discharge Consent (NDC)

We hold a regionwide NDC allowing the diversion and discharge of stormwater through the existing regional network.

If you have a project planned, we may be able to authorise the discharge of stormwater under the NDC.

For information, visit Design of the stormwater system.

Stormwater risks and requirements

Before you develop or purchase a site, make sure you are aware of any flood risks and stormwater requirements for that site:

• Get a Project Information Memorandum (PIM) and Land Information Memorandum (LIM) to find out if there are any identified stormwater issues.
• Consult relevant catchment management plan, stormwater management plans, and flood hazard maps.
• Visit the site to ensure that planning information matches the actual situation on the ground.
• Consider the capacity of both public and private drainage if the existing information is incomplete.

Before we can issue a building consent, structures must comply with both our and central government's policy on flood hazards. Consider these policies in the design of the stormwater system.

Stormwater network responsibilities

Auckland Council, Watercare, Auckland Transport and the landowner are responsible for their own assets.

These can be pipes, manholes or drains depending on where they are.

Visit Who maintains watercourses.

Built assets

We own and maintain public pipes, manholes, catchpits and other assets that manage stormwater flow, quantity and quality. View the public stormwater network using our GeoMaps viewer.

However, landowners are responsible for maintaining assets on their property up to the point where it connects to the public assets. This can include roof gutters, downpipes, grates and catchpits.

Generally, we determine the point between public and private assets as one of these:

• The connection to the public stormwater system regardless of the location or number of properties serviced.
• The point where the service connection serves more than one property.
• The point where the service connection crosses the property boundary.

Watercare infrastructure

Watercare maintains the pipes that supply water. This includes drinking water and water for your bathrooms and laundry.

They also handle enquiries about wastewater, including all wastes that go through household drains.

Visit the Watercare website.

Auckland Transport infrastructure

Auckland Transport takes care of streets and outdoor infrastructure. This includes grates, berms, footpaths, street lights, road signs and bus shelters, among others.

Visit the Auckland Transport website.