Early signs of a drainage problem in Toowoomba.

The useful warning signs are all small. That is the problem with them. None of these will ruin your weekend, which is exactly why they get ignored for years while the underlying fault quietly gets worse and more expensive.

• A green patch that stays green through a dry spell. The single most useful sign a homeowner gets, and we have given it its own section below.
• A gurgle or a slow drain after heavy rain, but not all the time. Intermittent means partial. Partial means it is still getting worse.
• A pit that holds water hours after the storm passed. A pit is supposed to drain down. One that does not is telling you about the line downstream.
• Moss or algae on a path that never used to be slippery. Something changed the moisture regime there, and it was not the path.
• A downpipe that overflows at the top in a real downpour. The line below it cannot take what the roof is delivering.
• Damp smell in a room after rain that clears in a few days. Water is getting somewhere it should not, and then leaving. It will not always leave.

Take the pit one further, because it comes up constantly. A pit still holding water hours later has only a few possible explanations: the line downstream is blocked with silt or roots, the pipe has lost its fall and developed a belly that holds water, the outlet itself is submerged or surcharged, or the pit has settled out of level, which happens readily in cracking clay. A camera identifies which of the four in a single visit. Guessing does not.

A CCTV camera inspection is $220 to $450 and it usually answers the question outright, with footage you keep. That is the honest starting point for anything involving an existing pipe, because it replaces guessing with seeing. If the camera finds a single failed section, a cut-out and re-lay is $650 to $2,500. If it finds an old earthenware line with roots at multiple joints and a bellied grade, replacement at $2,500 to $6,000 is the sensible call rather than patching one spot and coming back in two years. The site measure and the written quote are free. The camera is the only part worth paying for before you know what you are dealing with, and it is why we will not quote a blockage from the surface.

A worked example of catching it early. A Glenvale owner rang about nothing more than a green stripe across an otherwise brown September lawn, plus a slight gurgle from the downpipe after storms. No flooding, no damp, nothing that had cost him anything yet. We cameraed the line ($290) and found a joint pulled roughly 15 millimetres apart where the clay had worked it, leaking steadily into the surrounding soil, about 4 metres from the house wall. We cut out and re-laid 5 metres in uPVC on gravel bedding, $1,420. Total spend $1,710.

Left another three or four years, that same leak sits against footings in reactive clay, and the conversation stops being about pipe and starts being about the house. We are not going to tell you it definitely would have cracked the wall, because nobody can honestly say that. What we can say is that $1,710 bought certainty, and the version of this job we get called to more often is the one where the green patch was noticed years ago and nobody followed it up. If your yard is already past warning signs and into standing water, start with fixing a flooding backyard instead, and the cost guide has the full ranges either way.

What are the early warning signs of a drainage problem?

The useful ones are small and easy to dismiss. A patch of lawn that stays green through a dry spell, because something is feeding it water. A gurgle or a slow drain after heavy rain rather than all the time. A stormwater pit that holds water hours after the storm has passed. Moss or algae creeping across a path that never used to be slippery. A downpipe that overflows at the top in a real downpour. And a smell of damp in a room after rain that clears a few days later. None of these will ruin your weekend, which is exactly why they get ignored for years while the underlying fault gets worse and more expensive.

What does a stormwater pit full of water after a storm mean?

It means the water is not getting away, and there are only a few possible reasons. The line downstream is blocked with silt or roots. The pipe has lost its fall and developed a belly that holds water. The outlet itself is submerged or surcharged. Or the pit has settled out of level, which happens readily in Toowoomba’s cracking clay. A pit is supposed to drain down within a reasonable time after the rain stops. One that is still holding water hours later is telling you something specific about the line, and a camera will identify which of those four it is in a single visit.

Are cracks in walls a drainage problem in Toowoomba?

They can be, and here more than most places. Toowoomba sits on basalt-derived black cracking clay, classified under AS 2870 as highly to extremely reactive across much of the region. That soil swells when it gets wet and shrinks when it dries, and if one side of your house is being kept wet by a leaking drain or a downpipe discharging to ground while the other side dries out normally, the footings move differentially. That is a classic cause of stepped cracking in brickwork and doors that stick in one season. We are drainers, not engineers, so we will not diagnose your footings. But if you have cracking and a wet side, fixing the water is the first thing anyone will tell you to do.

Why does one patch of my lawn stay green in the dry?

Because something is watering it, and in the middle of a Toowoomba dry spell it is not the sky. The usual answers are a cracked or leaking stormwater line running beneath it, a joint that has pulled apart in the moving clay, or a subsoil drain that has blinded off and is now discharging into the ground rather than to its outlet. It is one of the more useful diagnostic signs available to a homeowner precisely because it is visible when everything else is dry and hiding. If a strip of your lawn is greener than the rest in September, follow it with your eye. It usually traces the line of a pipe.

How much does it cost to investigate a suspected drainage problem?

A CCTV camera inspection is $220 to $450 and it usually answers the question outright, with footage you keep. That is the honest starting point for anything involving an existing pipe, because it replaces guessing with seeing. If the camera finds a single failed section, a cut-out and re-lay is $650 to $2,500. If it finds an old earthenware line with roots at multiple joints and a bellied grade, replacement at $2,500 to $6,000 is the sensible call. The site measure and the written quote are free. The camera is the only part worth paying for before you know what you are dealing with.