Guide 05 · Stormwater
Stormwater rules, discharge and detention
Stormwater from a Queensland property must reach a lawful point of discharge nominated by the local government: the kerb, a council drainage pipe, or a registered easement. Development approvals add conditions — detention volume, discharge rate, water quality devices — and building to them is what gets a project signed off.
Last reviewed September 2026 · Confirm conditions against your approval and QDC MP 4.2
Where stormwater is allowed to go
Four discharge arrangements cover nearly every Queensland lot. Which one applies is a function of levels: whether the property falls toward the street, and whether the network in the street sits below the point where water leaves the site.
Kerb and channel
The standard arrangement for lots falling to the road. A kerb adaptor is cut into the kerb face and the private line discharges into the channel. The adaptor needs a council permit and reinstatement to specification.
Council drainage connection
A direct connection into a council pit or pipe, used where the kerb is unsuitable or the volume is significant. Council specifies the connection detail and inspects it.
Inter-allotment drainage
A piped line running through one or more downstream lots under a registered easement, used for properties with no fall to the street. Access chambers and easement widths govern the design.
Pumped discharge
A last resort on low-lying sites, accepted only where gravity is impossible. Councils scrutinise it closely because performance depends on a pump, and a pump depends on power.
On-site detention, explained without the hydrology
A paddock absorbs rain. A townhouse development sheds it in minutes. On-site detention exists to cancel that difference.
A detention system holds part of a storm in a tank, basin or underground chamber and releases it through a restricted outlet — commonly an orifice plate sized by the engineer. The result is a discharge rate no higher than the site produced before it was developed, which protects the downstream pipes, the neighbours and the creek.
Three things go wrong with detention on site. The volume gets reduced to fit the available space. The outlet gets installed at the wrong level or the wrong size. The tank gets built where a future driveway will sit over it without the required load rating. Each of those fails at inspection, and each is cheaper to avoid than to rebuild.
Water quality devices sit alongside detention on larger projects: gross pollutant traps, sediment basins and bio-retention inlets nominated by the stormwater quality plan. They are conditions of approval rather than optional extras.
A yard that floods: finding the actual cause
| Observation | What it points to | Fix |
|---|---|---|
| Ponding started after a neighbour built | Surface levels raised or flow concentrated across the boundary | Level survey, then council development compliance if the flow is redirected |
| Water backs up out of a grated pit | Silted or blocked private line, or a collapsed legacy pipe | Jet and camera the network, then replace the failed section |
| Downpipes discharge onto the ground | Roof water never connected to a piped system | Pipe the downpipes to the lawful point of discharge |
| Flooding only in heavy storms | Network sized for the original roof area, not the extension | Upsize the line or add capacity at the collection points |
| Ground stays wet with no rain | Groundwater, a leaking water service, or a failed sewer line | Subsoil drainage, or leak detection to rule out the other two |
Surface drainage never fixes a groundwater problem, and subsoil drainage never fixes overland flow. Diagnosing which one you have is the difference between a repair and an expensive experiment.
Questions
Who decides my lawful point of discharge?
The local government. It is nominated in the development approval or confirmed on request for existing properties, and it reflects the levels and the drainage network around the site rather than the owner's preference.
Can I build over a detention tank?
Only with a system rated for the load above it and maintained access to the outlet and inspection points. Retrofitting a driveway over a tank not designed for traffic means replacing the tank.
Who designs the stormwater system?
A hydraulic or civil engineer prepares the design and council approves it. We build to that documentation and raise any conflict between the drawing and the site before construction rather than after.
Is a rainwater tank the same as detention?
No. A rainwater tank stores water for reuse and is usually full when a storm arrives. A detention system must be empty and ready to fill. Combined tanks exist, with a dedicated detention volume above the reuse volume.
Continue
Approvals
Permits for kerb adaptors, road openings and drainage work.
Drain failure
When the blocked line is stormwater rather than sewer.
Stormwater services
Pits, pipes, detention, subsoil drainage and flooding repairs.
Send the drainage plan
Approved drawings back a fixed scope and a firm program.