Do I need a Stormwater Management Plan for my DA?

1. What is a Stormwater Management Plan and why does it matter?

A Stormwater Management Plan (SWMP) outlines how stormwater runoff will be managed on your site during and after development.

This includes the design of drainage systems, on-site detention, and erosion control.

In NSW planning, stormwater is a critical issue for residential and commercial developments.

Poorly managed runoff can cause flooding, damage infrastructure and pollute local waterways.

This is why many local councils require a SWMP as part of your development application.

2. When does council require a Stormwater Management Plan?

If your project increases hard surfaces, such as adding a new dwelling, extension or driveway, you’re likely to need one.

Most councils in NSW require a SWMP for any development over 50 square metres of impervious area.

This includes duplexes, granny flats, townhouses, commercial buildings and even large sheds.

In some areas, flood risk or existing drainage issues mean council approval will depend on a detailed stormwater solution.

We often see this in parts of the Inner West, Northern Beaches and Hills Shire, where drainage is tightly regulated.

3. What does a Stormwater Management Plan include?

A qualified engineer will prepare the SWMP in line with local council and NSW planning controls.

The plan typically includes site levels, proposed building footprints, discharge points, on-site detention tanks and compliance with the council’s water quantity and quality requirements.

It must show that stormwater can be safely collected and directed to a legal point of discharge without affecting neighbouring properties.

Your planning consultant will coordinate this with your architect and stormwater engineer to ensure DA approval is not delayed.

4. How does a SWMP affect my DA approval timeline?

Without a complete and compliant SWMP, your development application may be rejected or placed on hold.

This is especially common when applicants submit plans without first seeking expert planning advice.

At Town Planning Sydney, we work with engineers to deliver stormwater solutions that align with architectural design and council standards.

This ensures your DA moves through assessment smoothly and avoids unnecessary delays.

5. Do I need a SWMP for a CDC instead of a DA?

Yes, even under Complying Development, stormwater must be managed appropriately.

Private certifiers will request an engineer-certified stormwater plan before issuing a CDC.

So whether you’re applying through a DA or CDC pathway, proper stormwater planning is essential.

Our team helps clients across NSW prepare fast, compliant designs that meet all stormwater and drainage requirements.

6. Real-world example: Dual occupancy in Blacktown Council

A recent client approached us to prepare a DA for a dual occupancy on a sloped block in Blacktown.

The increase in roof area meant council required an on-site detention system to reduce stormwater runoff.

We coordinated with a stormwater engineer and submitted a SWMP alongside the architectural plans.

Because the plan met council’s drainage code, we secured DA approval without further requests.

Without this, the application would likely have been delayed or refused.

7. Planning advice for homeowners and developers

If you’re planning a development in NSW, speak to a planning consultant early.

Each council has different stormwater requirements, and assumptions can lead to major issues.

At Town Planning Sydney, we guide clients through the entire DA process including drafting, engineering coordination and council approval.

Whether it’s a new build, extension or commercial site, our planning advice is tailored to the specific needs of your project and local council rules.