Drains
Why does my yard flood when it rains?
A yard that floods in rain usually has a stormwater problem: blocked or undersized pipes, silted-up pits, a crushed line under a driveway, or a charged system that cannot cope with Sydney downpours. Clearing the pits, camera-inspecting the line and fixing broken sections restores drainage in most homes. Persistent soggy patches may need an absorption trench.
When a yard floods every time it rains, the water is telling you the stormwater system is either blocked, broken or was never big enough in the first place. Sydney downpours have become noticeably harder in recent years, and a system that coped with steady rain can be overwhelmed by 30mm arriving in half an hour. Before blaming the weather, though, it is worth checking the system itself, because most flooded yards Terry sees around Berala and the inner west come down to one of a handful of faults.
Blocked pipes and pits
The most common cause by far. Stormwater pits fill with leaves, silt and lawn clippings, and the pipes running from them clog with the same material plus tree roots. A pit that is full of sludge to within a hand-span of the grate is not collecting anything. Start there: lift the grates, scoop out the debris, and watch what happens in the next rain. If the pit fills but does not drain away, the pipe downstream is blocked, and that is a job for a jetter and usually a camera.
Crushed or broken lines
Stormwater pipes in older suburbs are frequently 90mm PVC or old terracotta laid shallow, and they get crushed by vehicles driving over lawns, by driveway construction and by tree roots. A crushed section acts like a dam, and everything upstream of it backs up and surfaces. The camera finds the spot, and the fix is either a dig-and-replace at that point or, where access is difficult, relining.
Charged systems that hold water
Many Sydney homes with rainwater tanks have charged, or wet, systems: the downpipes run underground and then rise up into the tank, so the pipes hold water permanently. These clog faster than free-draining lines because leaves and sediment sit in standing water, and when they block, the overflow appears at the lowest opening, often a downpipe joint or a yard gully, looking exactly like a yard drainage failure. If the flooding started after a tank was installed, this is the first suspect.
Undersized or missing drainage
Some yards simply never had enough drainage. A single 90mm line taking the roof, the paving and the lawn runoff will not cope with a summer storm. Low spots that hold water for days after rain, rather than during it, are usually a soakage problem rather than a pipe problem. Options include additional pits, grated channel drain across paths and driveways, upsizing the main run, or an absorption trench, a gravel-filled trench that stores runoff and lets it soak slowly into the soil, useful where there is no practical point of discharge to send the water to.
Where the water is allowed to go
Stormwater in NSW must discharge to a legal point, normally the street gutter or a council drainage easement, never into the sewer and never over the neighbour's fence. Redirecting flows is regulated work, which is one reason DIY yard drainage so often ends in a dispute or a redo.
The diagnosis path is simple: clear the pits, camera the lines, fix what the camera finds, and only then look at adding capacity. Terry handles all of it under NSW plumbing licence L10959, with a firm price before he starts. For a yard that turns into a pond every storm, call 0415 274 542.
Frequently asked questions
- Who is responsible for stormwater drainage, the council or the homeowner?
- The homeowner is responsible for all stormwater infrastructure within the property boundary, including pits, pipes and the connection to the legal point of discharge. Councils maintain the street gutters, kerb inlets and public drainage network. If your yard floods from your own blocked pipes, that is a private plumbing job, not a council one.
- Can I connect my stormwater to the sewer to get rid of it?
- No. Connecting stormwater to the sewer is illegal in NSW because storm flows overwhelm the sewer network and cause sewage overflows. Sydney Water actively investigates illegal connections and penalties apply. Stormwater must go to the street, a council easement or an approved on-site solution such as an absorption trench.
- How much does it cost to clear a blocked stormwater drain?
- A standard stormwater clear with a jetter sits in the same territory as sewer work, roughly $150–$350 in Sydney depending on access and how compacted the blockage is. A CCTV camera inspection, around $200–$400, is worth adding when the line blocks repeatedly, because it shows whether the cause is debris, roots or a crushed section.
- What is a charged stormwater system?
- A charged, or wet, system is one where the underground pipes permanently hold water, usually because they run below the inlet of a rainwater tank and rise up into it. They work fine when clean but clog faster than free-draining pipes, since debris settles in the standing water. They need accessible flushing points and an occasional clean-out to stay reliable.
- Will an absorption trench work in clay soil?
- Clay soils drain slowly, so an absorption trench in Western Sydney clay needs to be larger, shallower and longer than one in sandy soil to disperse the same volume. It still works when sized correctly, and it is often paired with upstream pits that catch silt before it reaches the trench. A soil check before design saves guesswork.
Related services
Need a hand from a real plumber?
Terry's been sorting plumbing across Berala and Western Sydney since 1986. Call 0415 274 542 for a straight answer and a fixed price.
NSW Licence L10959 · 40+ years experience