Backyard flooding after rain is a stormwater problem, not a sewer one. They are two entirely separate systems, and if water is pooling in your yard while everything inside the house drains normally, the fault is in the system that handles rain.
That is good news and bad news. Good, because it is rarely an emergency. Bad, because on a Sydney property almost all of it is your responsibility, right out to the kerb.
Quick answer
- Pools near a downpipe: the downpipe is not connected properly, or the line below it is blocked.
- Pools around a grated pit: the pit or the line leaving it is blocked.
- Pools in the middle of the lawn with no pit nearby: a grade problem, not a pipe problem.
- Water reaching the house: deal with it now. That is the version that gets expensive.
Stormwater and Sewer Are Two Different Systems
This is worth thirty seconds because almost everything else on this page follows from it.
Your sewer line takes wastewater from toilets, showers, sinks and appliances to Sydney Water’s network. Your stormwater system takes rain from your roof, driveway and yard to a separate discharge point, usually the kerb out the front.
They are not connected, and connecting them is not allowed. Rain volumes would overwhelm the sewer, which is why stormwater entering a sewer line is treated as a fault rather than a shortcut.
So a flooded yard with normal indoor drainage means the stormwater system has failed while the sewer is fine. If the water in your yard smells, or waste appears in a fixture indoors, that is a different and more urgent problem: see sewage coming up the shower drain.
Where the Water Pools Tells You What Is Wrong
Walk the yard while it is still wet. Location is the diagnostic.
| Where it pools | Most likely cause |
|---|---|
| At the base of a downpipe | Downpipe discharging to the surface, or the line below it blocked or broken. |
| Around a grated pit that stays full | Silt and leaves in the pit, or a blockage in the line leaving it |
| A low spot in open lawn, no pit nearby | Grade. The ground has nowhere to send the water |
| Along a fence line or against a retaining wall | Runoff arriving from next door, or a blocked subsoil drain behind the wall |
| Against the house, near the slab or footings | Ground falling toward the building. The one to fix first |
| Everywhere, but gone within an hour or two | Possibly nothing. Heavy Sydney downpours outrun any system briefly |
The last row matters. Water that clears within a couple of hours after a genuine downpour is a system coping, not failing. Water still sitting the next morning is not.
The Five Causes, in Order
1. A blocked stormwater pit. The most common and the easiest to fix. Grated pits collect leaves, silt and mulch, and Sydney’s tree canopy fills them faster than most owners expect. If the pit is full of standing water and debris, that is your answer.
2. A blocked or broken stormwater line. The pipe leaving the pit runs underground to the kerb and fails the same way a sewer does: roots at the joints, silt, cracked sections, a collapse under a driveway. On older Sydney properties, it is often the same age and material as the sewer line, with the same problems.
3. Downpipes that do not go anywhere. A downpipe should connect into the stormwater line, not discharge onto the ground or into a garden bed. Renovations, decks and landscaping regularly disconnect one, and a single roof face delivers an enormous volume to that one spot. Check the gutters at the same time, since roof plumbing and stormwater are one continuous path.
4. Grade. The ground falls the wrong way. Usually created rather than original: a new deck, raised garden beds, paving, a turf top-dress that lifted a level. No pipe repair fixes this, which is why it gets misdiagnosed and paid for twice.
5. Volume that exceeds the system. Older properties were drained for the roof area and hard surfaces they had at the time. Add a carport, an extension and a paved entertaining area, and the same pipe carries considerably more than it was sized for.
What You Can Check Yourself
While it is raining, if it is safe to be outside: watch where water arrives and where it stops. This is the single most useful thing you can do, and it is impossible to reconstruct afterwards. Take a video.
Lift the grate on every pit and look. Debris packed to the top means the pit. Clean and free-draining means the line beyond it.
Check the base of every downpipe. Follow it down. Does it enter a pipe in the ground, or stop short? A disconnected downpipe is visible in ten seconds and explains a surprising number of flooded yards.
Clear the gutters before you spend anything. Overflowing gutters dump water directly against the wall of the house, and it looks exactly like a drainage fault at ground level.
Do not connect anything to your sewer, and do not redirect water toward a boundary. Sending runoff onto a neighbouring property is not permitted, and doing it deliberately turns a drainage problem into a dispute.
The pit is clear, and it still floods?
Call R&G on 0420 146 747. If the pit and the downpipes are fine, the problem is in the line or the levels, and those need locating rather than guessing. $0 call-out fee, fixed price before any work starts.
Who Is Responsible? Further Out Than You Think
People assume stormwater works like sewer, where your responsibility ends at a connection point near the boundary. It does not.
In NSW, you are responsible for the stormwater pipes, pits and channels on your property all the way to the legal point of discharge, which is usually the kerb and gutter at the front. A stormwater line collapsed under your own driveway is entirely yours, even though the equivalent sewer fault might not be.
Your local council maintains the public network beyond that: street drains, kerb and gutter, easements and the pipes in the road reserve. Sydney Water maintains larger stormwater channels across several council areas, but for a residential backyard it will rarely be them.
Two obligations worth knowing, because they come up in neighbour disputes. You are required to maintain the drainage within your boundary, and you are not permitted to direct runoff onto a neighbouring property. If water is arriving from next door, the first step is a conversation, and the second is your council rather than a plumber.
What a Plumber Does About It
Confirms it is pipes and not levels. The cheapest possible outcome is discovering that no pipework will help, and finding that out before you pay for pipework is the point.
Clears and inspects the line. Jetting removes silt and root matter from a stormwater line, and a camera run afterwards shows whether the pipe is sound or whether there is a crack, a collapse or a bellied section holding water. That is also what tells you whether you need a drain repair or just a clean.
Fixes what the inspection found. Reconnecting a downpipe, replacing a pit, repairing a section of line, adding capacity, or regrading where the fall genuinely does not work.
One connection worth making: if your indoor drains also gurgle during or after heavy rain, that is stormwater getting into your sewer line through a crack, which is a separate fault from the yard flooding and worth mentioning when you call.
More on how we find and clear blocked stormwater drains across Sydney.
Frequently Asked Questions
How long should water take to drain from my yard?
After heavy rain stops, surface water should be gone within a few hours. Puddles still sitting the next morning, or ground that stays soft for days, means water is not getting away rather than simply arriving faster than it can leave.
Is backyard flooding actually a problem if it does not reach the house?
It is worth fixing before it becomes one. Persistent saturation kills lawn and plants, breeds mosquitoes, and undermines paving and retaining walls over time. Water repeatedly sitting against footings is the version that turns into a structural cost.
Water is coming from my neighbour’s property. What can I do?
Property owners are not permitted to direct runoff onto neighbouring land. Start with a conversation, since it is often unintentional and caused by recent landscaping or paving. If that does not resolve it, your local council handles the complaint, not Sydney Water and not a plumber.
Can I connect my stormwater into the sewer to fix it?
No. It is not permitted, and for good reason: rain volumes would overwhelm the sewer network and cause overflows. Stormwater entering a sewer line is treated as a defect to be repaired, not a solution.
Stop it before the next storm.
We find out whether it is the pit, the line or the levels before quoting anything, because those are three different jobs at three different prices. If clearing a pit fixes it, that is what we will tell you. $0 call-out fee, fixed price before any work starts, across the North Shore, the Hills and Western Sydney. See how we handle blocked drains across Sydney.
