Top 5 Mistakes in WSUD Planning (And How to Avoid Them)

Most WSUD (Water Sensitive Urban Design) plans fail because small details are missed early in the planning process. That could be due to the wrong treatment type, incorrect STORM modelling, or failure to consider council-specific requirements. 

These little mistakes can turn into costly redesigns and delay your planning approval, without which you cannot move forward. 

In this guide, we’ll break down the top five WSUD planning mistakes and ways to avoid them so you can get approved fast. Let’s get into it.

Five Mistakes in WSUD Planning And How to Avoid Them

If the wrong assumptions are made at the start, projects get stuck in back-and-forth emails, redesign, and additional planning costs. This is why you should understand these mistakes upfront to avoid any revisions and submit a WSUD plan that gets approved the first time. 

With that said, here are the five mistakes that usually come with WSUD planning and how you can avoid them. 

Mistake 1: Ignoring the Council’s Preferred WSUD Treatment Types

Many developers assume that all councils accept the same WSUD treatment solutions, but that isn’t true. Each council has a preferred treatment hierarchy, and some completely restrict certain options. 

For instance, Maroondah typically discourages or limits rain gardens, so the design must use alternative methods, such as permeable paving or tank collection. 

When a designer selects a treatment type the council doesn’t prefer, the application is either rejected or sent back for revisions. This creates delays, redraws, additional consulting fees, and frustration. 

How to Avoid It

• Check council WSUD guidelines before choosing treatments.
• Confirm which treatment types are acceptable and which are restricted.
• Ask your assessor early to recommend the most cost-effective option.

Mistake 2: Not Knowing What the Council Will Not Allow

Another reason submissions fail is that the design includes elements the council simply doesn’t permit. This isn’t just limited to the treatment types. 

It also includes location rules, discharge constraints, material restrictions, visibility and maintenance rules, or site-context limits.

When these “red lines” are missed, plans bounce back for redesign. That means re-modelling, new drawings, and delays. Councils publish these constraints in their ESD/WSUD guidelines and often in planning checklists, but they are easy to overlook during early design.

How to Avoid It 

• Download and follow the council’s WSUD/ESD guideline. 
• Check location, setback, discharge, and visibility restrictions. 
• Book a pre-application check or email the council’s sustainability officer for written confirmation.

Mistake 3: Designing Without Allocating Space for WSUD Solutions

WSUD solutions, like underground tanks, permeable paving zones, and rain gardens, take up physical space. However, many designs fail to set aside space early and later discover the treatment cannot fit without reconfiguring parking or landscaping.

This happens because WSUD is viewed as “just a calculator requirement,” not a spatial design item. By the time everyone realises space is missing, the drawings are too far advanced and costly to change. 

How to Avoid It 

• Allocate dedicated space for WSUD elements (tanks, gardens, infiltration zones).
• Mark the space clearly in site design drawings before finalising roads, drives or landscaping. 
• Review the minimum area requirements for your chosen treatment method. 

Mistake 4: Miscalculating Roof Areas and Capture Zones

WSUD systems depend on where stormwater flows from, not just roof size. A common mistake people make here is miscalculating the total roof area and then feeding it into a single treatment system. 

However, the problem here is that WSUD tools assess how much each roof catchment connects to a specific treatment type. If calculations are wrong, the STORM scorecard won’t reach 100% and the council will flag it for revision. 

This error usually occurs when catchments are manually estimated or assumptions are made during early design.

How to Avoid It 

• Determine the roof and impervious surface capture area in early design. 
• Match the catch area to the correct treatment type for that volume. 
• Use the STORM-scorecard to test roof-capture volumes. 

Mistake 5: Incorrect Hard Surface Area Calculations

The last mistake that’s quite common is incorrectly categorising areas like driveways, concrete paths, balconies, and paved courtyards. You should know that hard surface areas determine the runoff volume and, therefore, the treatment system size.

When you underestimate these areas, the result would be a WSUD score that looks compliant on paper but fails in review. Overestimating these areas can also inflate the construction costs. 

Both errors can cause problems, which is why your calculations must be highly accurate.

How to Avoid It 

• Clearly label and measure all hard surfaces in your design drawings. 
• Include full square-metre calculations for those areas in your submission.
• Use modelling software or a qualified consultant to validate hard surface runoff.

Ready to Get Your WSUD Assessment Approved?

WSUD planning can feel like a maze. One wrong treatment choice or a missing detail can stall your submission. However, the good news is you don’t have to take on all the stress, because PassivEnergy is here to help you out. 

We simplify WSUD compliance by handling the entire process for you. Our team already knows what each council prefers, what they reject, and how to design a compliant solution without having to redesign half your project.

Get a quick quote and let us remove the guesswork from WSUD compliance!