Older brick house in Cabramatta, first big storm of the season. The downpipe on the back corner was spraying out of the elbow at the bottom like a hose with a thumb over it, and the water was running straight under the house. The gutter was fine. The downpipe was fine. The 90mm stormwater pipe it fed had been full of tree roots for years, and every storm since had dumped the whole back roof against the footings. That is the most common downpipe call I get across South West Sydney, and the fix was underground, not on the wall.
The rule I use: look at where it overflows. Top of the downpipe, the problem is above it, in the gutter or the downpipe head. Bottom, the problem is below it, in the stormwater. In between, the downpipe itself has split or a joint has pulled apart. That tells you who to ring and whether it can wait. We do roof plumbing and stormwater, no call-out fee, across Liverpool, Fairfield and Macarthur, with our own excavator.
A downpipe overflowing at the top means the gutter or the downpipe outlet is blocked, or there are too few downpipes. Overflowing at the bottom means the stormwater pipe it feeds is blocked or was never connected. Clear leaves from the top and check the base yourself; anything underground, and any downpipe discharging onto the soil, needs a plumber to connect it properly to the stormwater system.
Where a downpipe overflows tells you what is wrong
Downpipe overflowing at the top
Water sheeting over the gutter edge, or pouring out of the rainhead. The gutter is blocked with leaves, the outlet into the downpipe has a bird's nest or a tennis ball in it, or there are not enough downpipes for the length of gutter. The National Construction Code's housing provisions for gutters and downpipes allow each downpipe no more than 12 metres of gutter, and plenty of older houses in Fairfield have one downpipe doing the work of two. Ten minutes of gutter overflowing in a cloudburst is the storm beating the gutter. A gutter overflowing every time it rains is a blockage or a design problem, and it rots the fascia while you think about it.
Downpipe overflowing at the bottom
Water spurting from the joint at the base, or bubbling up out of the ground beside the pipe. That is the stormwater line backing up. It is blocked with silt or roots, it has been crushed, or on older blocks it runs to a rubble pit that silted up decades ago. The gutter and downpipe are doing their job; the pipe under the lawn is not.
Downpipe leaking part way down
A wet stripe down the brickwork below a joint, or a drip from the middle of the pipe. PVC goes brittle in the sun and splits, joints pull apart when a bracket rusts off the wall, and steel downpipes rust through at the base where the splash sits. That is a downpipe repair for a roof plumber, a new section and a couple of brackets, and it can wait for a dry week.
Blocked downpipe: how to check and clear it yourself
Start in the rain, from the ground, with a coffee. Watching which downpipes run and which do not tells you more in five minutes than an hour on a ladder. Then, on a single storey with a stable ladder and someone holding it, clear the gutter outlet and push a hose down the downpipe at full pressure. A soft plug of leaves usually moves. If the hose water backs up and comes out at the base, the blockage is underground and you have found the limit of the DIY.
The bottom elbow on most PVC downpipes is a push fit, so you can pull it off and clear the base by hand. Do not tip drain cleaner down it, and do not get on a two storey roof or a steep tile roof to clean a gutter; that is what harness-wearing gutter cleaners are for.
Downpipe not connected to stormwater: the big one
Nobody notices this one until the house cracks. On older blocks around Cabramatta and Fairfield the downpipes were often run onto a splash block or into a rubble pit that stopped absorbing anything long ago. On new builds in Leppington and Austral I still find a downpipe that just stops in the dirt beside the slab, because the drainer ran out of pipe on a Friday. Renovations do it too: an extension moves a downpipe and the old connection is abandoned, or a rainwater tank goes in and its overflow never gets connected.
Why it matters. The soils across Liverpool, Camden and Campbelltown are reactive clay. Wet one corner of the house every time it rains and the clay swells; let it dry out in summer and it shrinks. The footings move with it, and you get stepped cracks in the brickwork, doors that stick and tiles that pop. A downpipe dumping the whole roof against one corner is one of the most common causes of cracked brickwork I see. Under the floor it means damp, mould and termites. The Code's housing provisions require the stormwater to be discharged in a position and manner the council is satisfied with; a pipe that ends in the soil beside the footings is not that, and you cannot lawfully send it onto the neighbour's block either.
The fix is a proper downpipe to stormwater connection. If there is an existing stormwater line with capacity, I camera it first, then tie the downpipe into it with glued 90mm PVC laid with fall. If there is no line, it is a new run to the kerb, the inter-allotment drain or the easement: a trench with the mini excavator or a Grundomat bore under the driveway, and a kerb outlet cut into the gutter with council's consent. Never the sewer: roof water overloads it and Sydney Water can make you disconnect it. Blocked stormwater drains and pits covers what happens when the line is there but choked.
Symptoms, causes and who fixes them
| What you see | Likely cause | Who fixes it |
|---|---|---|
| Gutter overflows along its length in heavy rain | Gutter blocked, no fall, or too few downpipes | Clean it yourself; roof plumber for gutter repair or extra downpipes |
| Overflows at the rainhead or top of the downpipe only | Outlet or top of the downpipe blocked | Clear from the top with a hose |
| Spurts from the elbow at the base | Stormwater line blocked or collapsed | Plumber: camera, jet blast, or dig and replace |
| Bubbles up out of the ground beside the pipe | Line blocked, or the pipe just ends in the soil | Plumber: connect it to the stormwater |
| Wet stripe on the wall below a joint | Split pipe or a joint pulled apart | Roof plumber: replace the section and brackets |
Downpipe repair: what a plumber does and what a roof plumber does
In NSW, roof plumbing is its own licence category, and it covers guttering, roof flashings, roof sheeting and the downpipes on the wall. A full regutter, a new box gutter, a rainhead or a leaking valley is roof plumber work and I will say so on the phone. My licence is plumbing, drainage and gasfitting, so I take it from the base of the downpipe down: the connection into the ground, the underground stormwater line, the pits and the kerb. Most downpipe problems people ring about live in that bottom half, because that is where the water goes wrong. Not sure which trade you need? Roof plumber vs plumber sorts it out, or ring and describe where the water is coming out.
What downpipe and stormwater repairs cost
Jet blasting a blocked stormwater line sits at $180 to $450 on Sydney 2026 price guides, with a call-out fee of $69 to $170, and the camera is usually bundled with the clear. Reconnecting a downpipe, replacing a split section, or running a new line to the kerb is quoted on inspection. What moves the price is length and depth, concrete or a driveway in the way, bore or trench, the council permit for the kerb outlet, and how much lawn goes back. A downpipe fault is a business-hours job, so there is no need for a night call-out. Gutter work is quoted by the roof plumber. You get the price before anyone starts. Done right. Done once.
When to call a plumber about a downpipe
Call when the downpipe spurts or bubbles at the base, when the ground around it stays wet for days after rain, when a downpipe simply ends in the dirt, when new cracks appear in the brickwork near a downpipe, or when roof water is getting under the house or into the garage. Call the week you notice it, not during the next east coast low when every stormwater plumber in Sydney is under water. It is only an emergency call when water is entering the house.
Monarch Civil & Plumbing is a stormwater plumber across South West Sydney and the Macarthur region, based in Austral. See the blocked drains page for how a choked line gets cleared, and if you need a plumber in Cabramatta, a plumber in Leppington or anywhere between, ring 0455 222 292 and tell me where the water is coming out.
Related guides: blocked stormwater drains.
Need it sorted? Ring 0455 222 292 any hour or book online. Monarch Civil & Plumbing does roof plumbing and stormwater, no call-out fee: pits, lines, kerb outlets and absorption trenches, quoted before we start.
Getting a plumber in South West Sydney?
How we work explains the no-call-out-fee promise and how a quote works. The suburb pages for plumber Liverpool, plumber Fairfield, plumber Campbelltown and plumber Camden say what we see locally, and service areas lists every suburb within about 20 km of Austral, plus Wollongong and the Illawarra regularly.
Frequently asked
Why is my downpipe overflowing at the bottom?
Because the stormwater pipe it feeds cannot take the water. Usually the underground line is blocked with silt or tree roots, sometimes it has been crushed, and on older houses it often runs to a rubble pit that stopped absorbing water decades ago. The gutter and the downpipe are fine; the water has nowhere to go. A camera down the line shows which it is, and a jet blast or a new section fixes it.
Does a downpipe have to be connected to stormwater in NSW?
Yes. Roof water has to go to an approved point of discharge, which for most houses is a kerb outlet, an inter-allotment drain or an easement, and the National Construction Code's housing provisions require the stormwater to be discharged in a position and manner the council is satisfied with. It can never go into the sewer, and it cannot be sent onto a neighbour's land. A downpipe that ends in the dirt needs connecting.
Can a downpipe discharging onto the ground damage my house?
It can, and across Liverpool, Camden and Campbelltown it regularly does. The soil is reactive clay that swells when it is wet and shrinks when it dries, so a downpipe dumping the whole roof against one corner moves the footings and cracks the brickwork. It also keeps the subfloor damp, which brings mould and attracts termites. Connecting that downpipe to the stormwater is cheaper than underpinning.
Who fixes a leaking downpipe, a plumber or a roof plumber?
In NSW roof plumbing is a separate licence category covering gutters, flashings, roofing and the downpipes on the wall, so a regutter or a new rainhead is a roof plumber's job. A plumber and drainer handles it from the base of the downpipe down, where it becomes stormwater: the connection into the ground, the underground pipe, pits and the kerb outlet. Ring either, describe where the water comes out, and an honest tradie will tell you which one you need.
How do I unblock a downpipe myself?
From a stable ladder on a single storey, clear the gutter outlet by hand, then push a hose down the downpipe at full pressure. Most leaf plugs shift. Pull the push fit elbow off the bottom and clear the base by hand. If hose water backs up and comes out at the base, the blockage is in the underground pipe and it needs a plumber with a jet blaster. Stay off two storey roofs and leave chemicals out of it.
How much does it cost to fix a downpipe or stormwater problem?
Jet blasting a blocked stormwater line sits around $180 to $450 on Sydney 2026 price guides, plus a call-out fee of $69 to $170, and the camera inspection is usually bundled in. Reconnecting a downpipe, replacing a split section or running a new line to the kerb is quoted on inspection, and length, depth, concrete in the way and the council permit for a kerb outlet are what move the price. It is a business hours job, so no need for a night call-out.
Licensed plumber and drainer based in Austral, 13+ years in the trade, working across Liverpool, Fairfield and the Macarthur region. About Paul