Auckland Council

Source Documents

These are the council documents used to build the AC calculator. If a link is broken, the document may have moved on the council website.

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GD01 Stormwater Management Devices (Dec 2025) + Auckland Unitary Plan E10

PDF Primary Source

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AC Stormwater Information Page

Council website - may contain updated links if documents above have moved.

Calculation Methodology

Retention

5mm runoff depth x impervious area

Method

SMAF area-based calculation (GD01 Section B1.7.1.1). Retention = 5mm depth x impervious. Detention = 18.5mm x impervious area. 24-hour drain-down. Resource consent required in SMAF areas.

Design Requirements

• SMAF1/SMAF2 overlay check required (Auckland Unitary Plan maps)
• Retention: min 5mm runoff depth for impervious area
• Detention: 24-hour drain-down period
• Min 1,000L detention-only tank; min 4,500L dual-purpose tank
• Resource consent required in SMAF areas (over 50m2 new impervious)
• Design per GD01 + TP108 methodology

Submission