Blocked Stormwater Drains in the Northern Rivers: Why It Happens Every Storm Season
A blocked stormwater drain shows up as water pooling around downpipes, overflowing gutters during rain, soggy patches in the yard that never dry out, or water sheeting across paths and into the garage. The blockage is almost always leaf litter, silt or tree roots, and in the Northern Rivers it needs sorting before storm season, not during it. Minor surface blockages you can clear yourself; anything underground needs a jetter and a camera.
Here's how the system works, what you can safely do, and when it's a plumber's job.
What Does a Stormwater Drain Actually Do?
Your stormwater system is completely separate from your sewer. It collects rain from the roof via gutters and downpipes, plus surface water from grated drains and pits around the property, and carries it to the street kerb, a council main or a soakage point. When it blocks, the water has nowhere to go, so it goes wherever gravity takes it: under the house, into the garage, against the slab.
In this region that matters more than most. Northern Rivers summer storms can dump enormous volumes of rain in an hour, and homes across Lennox Head, Ocean Shores, Mullumbimby and Ballina sit on sandy coastal soil that washes silt into pipes, surrounded by camphor laurels and figs whose roots hunt for exactly this kind of water source. The 2022 floods showed everyone what happens when water can't get away. A blocked stormwater line is the household-scale version of the same problem.
How to Unblock a Stormwater Drain Yourself
Safe DIY, in order:
Clear the grates and pits. Lift the grate on each stormwater pit and scoop out leaves, silt and debris by hand or with a small spade. This alone fixes a surprising number of "blocked drain" problems.
Flush downpipes with a hose. Run a garden hose at full pressure into the downpipe. If water backs up out of the pipe instead of flowing away, the blockage is underground.
Clean gutters and leaf guards. Blocked stormwater often starts at the top. If gutters overflow before water ever reaches the downpipe, the drain gets blamed for a gutter problem.
Check the kerb outlet. Look at where your stormwater discharges at the street. If nothing comes out while the hose is running, the line is obstructed somewhere between.
If the hose test backs up, stop there. A garden hose won't shift compacted silt or roots, and hardware-store drain snakes rarely make it through stormwater bends (the same limits we cover in how to unblock a drain). Underground blockages need a high-pressure jetter, and if the line blocks again after jetting, a CCTV drain inspection will show whether roots or a collapsed pipe are the real cause.
How Do I Find Stormwater Pipes on My Property?
Start at the downpipes; every one connects to the stormwater system. Follow the logical straight line from each downpipe toward the street kerb, the lowest point of the block, or a visible pit. Council holds drainage diagrams for most properties (Ballina Shire and Byron Shire both provide these on request), which show the as-built layout. Where diagrams don't exist or don't match reality, which is common on older Northern Rivers homes that have been extended, a plumber can trace the line with a camera and locator and mark exactly where it runs and how deep.
Why Do Stormwater Drains Keep Blocking?
Tree roots. The number one cause of repeat blockages here. Stormwater pipes carry water and sit shallower than sewer lines, which makes them the first thing roots find. Camphor laurel and fig roots can fill a 90mm pipe completely.
Silt and sand. Coastal soil washes fine sediment into the system with every downpour. It settles in flat sections and pipe bellies and slowly chokes the line.
Leaf litter. Especially under large established trees, and especially where gutters have no leaf guards.
Crushed or collapsed pipe. Older terracotta stormwater lines crack under driveways and vehicle traffic, then catch everything that flows past.
A line that blocks every storm season has one of these underlying causes, and clearing it each time without diagnosing it is just renting a solution.
When to Call a Plumber
Call if water is backing up from underground pipes, pooling against the house or slab, entering the garage or subfloor, or if the same line blocks more than once a year. Water against your foundations does quiet, expensive damage; if you're also seeing damp walls or unexplained wet patches, it's worth reading about leak detection too, because stormwater and hidden leaks produce similar symptoms.
Jesse at JF Plumbing jets, camera-inspects and repairs stormwater lines across Lennox Head, Ballina, Byron Bay and the wider Northern Rivers. With over 8 years of plumbing experience, his approach is to find the actual cause on camera, then fix that, rather than clearing the same blocked drain every December.
FAQ
Is a blocked stormwater drain the council's problem or mine? Everything on your side of the property boundary is yours. The council is responsible for the kerb, street gutters and public mains. If your line is clear but water backs up from the street connection, report it to council.
Can I pour anything down a stormwater drain to clear it? No. Chemical cleaners don't work on silt and roots, and stormwater discharges to creeks and the ocean, so anything you pour in ends up in the environment. Mechanical clearing is the only real option.
How much does it cost to unblock a stormwater drain? It depends on the cause and access. A straightforward jetting is a quick job; root-cut and repair work costs more. A camera inspection first means you're quoted on the actual problem.
Should I get stormwater checked before storm season? Yes. A pre-summer jet and inspection is far cheaper than an emergency call-out during a downpour, and storm season is exactly when plumbers are hardest to book. It slots into the rest of our seasonal plumbing maintenance checklist.
Sort it before the next storm. JF Plumbing services the whole Northern Rivers. Meet Jesse and the team or call 0412 230 635.
