STORMWATER & DRAINAGE · VICTORIA
Stormwater and Drainage When Building or Extending a Home in Victoria
Stormwater design affects site levels, roofs, paving, landscaping and where water can legally leave the property.
Short answer
Before building or extending, identify how roof and surface water will be collected, detained, reused or discharged and which authority requirements apply. The design should coordinate roof drainage, site grading, retaining walls, paving and overland flow so the project does not create nuisance flooding or send concentrated runoff toward neighbouring property.
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Stormwater Drainage for Building & Extensions in Victoria
EBC explains site fall, legal point of discharge, pits, pipes and detention considerations that can affect new-home and extension design.
Start with the legal discharge point and site levels
The project team needs to know where stormwater is permitted to discharge and how the property levels allow water to reach that point.
On a sloping or constrained site, this can influence finished floor levels, pits, pumps, detention or other drainage measures.
Hard surfaces increase runoff
Roofs, driveways and paving reduce the amount of rainfall that can soak into the ground. Victorian residential planning standards include permeability and stormwater considerations to reduce pressure on drainage systems.
Landscape and drainage design should therefore be coordinated with the building footprint rather than added at the end.
Retaining walls and drainage are closely linked
Retaining changes the natural movement of surface and groundwater. Drainage behind walls and the treatment of the surrounding levels are important to long-term performance.
The civil, hydraulic and structural requirements should be coordinated for the actual site.
Check authority requirements early
Depending on the project and catchment, local council, Melbourne Water or another drainage authority may have requirements that affect the design.
Early confirmation reduces the risk of redesign after architectural plans are advanced.
Planning a project like this? EBC builds home extensions across Melbourne's Eastern Suburbs, and can talk through how this applies to your home.
Questions homeowners ask
What is a legal point of discharge?+
It is the approved location or system to which site stormwater can be discharged. The relevant authority can confirm the requirement for the property.
Can I send stormwater toward the street or neighbour?+
Stormwater must be managed in accordance with the applicable drainage and permit requirements; it should not be redirected in a way that creates nuisance or damage.
Does paving affect stormwater design?+
Yes. More impervious surface generally increases runoff, which can affect permeability, detention and drainage requirements.
When should drainage be designed?+
Early enough to coordinate with building levels, landscaping, retaining walls and the legal discharge point.
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