Fixing drainage before selling in Toowoomba.
Drainage is the least glamorous pre-sale spend there is, and one of the few that reliably stops a buyer knocking money off. Here is an honest look at what it does and does not return, and which jobs are worth doing before you list.
Drainage protects your price, it does not add to it.
We will not pretend otherwise: nobody pays a premium for an ag drain they cannot see. Put a new kitchen in and a buyer walks in and reacts to it. Put 30 metres of slotted pipe in a gravel trench under the lawn and the buyer will never know it is there. If you are looking for a renovation that lifts the asking price, this is not it.
What drainage does is defensive, and on a bad enough problem it is the best money in the whole campaign. It removes the thing the building inspector will write up and the buyer will use to negotiate. A $4,000 drainage fix rarely adds $4,000 to the sale price. But a wet subfloor noted in a building and pest report routinely costs a seller a good deal more than that, because the buyer does not price the actual repair, they price the worst case, and their solicitor advises them to. A vague finding about moisture under a house on black soil invites a buyer to imagine footing movement, and imagination is expensive.
There is a second effect that is harder to put a number on. A finding that turns up after the contract is signed does not just cost money, it costs momentum. Buyers who get spooked during the inspection period sometimes walk entirely, and a property that comes back on the market after a failed contract carries a question mark that a second buyer can smell. Clearing the problem before you list keeps the negotiation about the house.
What the building and pest inspector is looking for.
Water is what causes most of the defects an inspector is paid to find, so drainage is near the top of their list, not an afterthought. Expect them to check whether the ground actually falls away from the house, whether the downpipes connect to a stormwater line or simply spill onto the dirt, whether the subfloor is damp, and whether there is staining, movement or a termite conducive condition around the perimeter.
In Toowoomba the inspector has an extra reason to care. The city sits on black cracking clay, a basalt-derived vertosol classified under AS 2870 as highly to extremely reactive on plenty of sites. That soil shrinks and swells dramatically with moisture, which is why a leaking or missing drain here is not just a wet-lawn problem, it is a footing-movement problem. Any inspector who works this region knows it, and they write it up in plain language. These are the findings we see quoted back to us most often:
- Downpipes discharging to ground. Cheap to fix, and one of the most commonly noted items in the report.
- Ground falling toward the dwelling. Reads badly, because it points straight at the footings.
- Damp or poorly ventilated subfloor. Invites a termite comment in the same paragraph.
- Ponding water adjacent to the slab. On reactive clay this is the one that makes buyers nervous.
- Blocked or surcharging stormwater pits. Suggests a problem further down the line that nobody has diagnosed.
On disclosure, Queensland has had a mandatory seller disclosure regime since 1 August 2025, requiring a disclosure statement and prescribed certificates before the contract is signed. That regime is largely about title, encumbrances, rates and notices rather than a general confession of every defect, so it does not by itself force you to write down that the back yard gets boggy. What it does not do is protect you if you actively conceal a known problem or answer a direct question dishonestly. The clean path is to fix it, keep the invoice, and hand the paperwork over as evidence.
Which jobs are worth it, and a worked example.
The rule we give sellers is simple: deal with what a buyer or an inspector will see in the next few weeks, and leave the rest for the next owner. Worth doing before you list: connect any downpipes discharging onto the ground, clear and camera a stormwater line that is known to back up, and fix ponding or a boggy patch that will not have dried out by inspection day. Usually not worth doing: a full ag drain system on a yard that only goes wet in an exceptional storm, or a detention tank nobody has asked for.
The budget is usually smaller than people fear. Re-piping loose downpipes into an existing line runs from a few hundred dollars to about $1,500. A camera inspection is $220 to $450 and a blocked drain clear is $350 to $900. A spoon drain or swale to kill a wet patch is $60 to $130 a lineal metre. It only gets serious if you need a full stormwater connection at $2,500 to $6,000, or an ag drain system at $80 to $140 a lineal metre. Most pre-sale tidy-ups land between $1,200 and $4,000.
A worked example. A 1960s home at Middle Ridge going to auction in six weeks, where three downpipes emptied straight onto the ground on the high side and the resulting water ran along the wall to pond at the rear corner. The owner had already had one buyer walk after a building report flagged subfloor moisture. We collected the three downpipes and piped them 18 metres to the existing kerb outlet ($1,340), cut a short spoon drain across the rear to lead surface water away ($680) and re-graded the ponding corner ($420). Total $2,440. The second building report noted drainage as satisfactory, and the contract ran to settlement without a reduction. That is what defensive spending looks like when it works.
If you are not sure whether your yard is a small tidy-up or a real problem, the honest first step is a look at it. Read fixing a flooding backyard for the difference between surface water and groundwater, because the answer changes the budget by thousands.
Pre-sale drainage across Toowoomba.
Common pre-sale drainage questions.
Does fixing drainage add value before selling in Toowoomba?
Not in the way a new kitchen does. Nobody pays a premium for an ag drain they cannot see. What drainage does is protect the price you were already going to get, by removing the thing a building inspector will write up and a buyer will use to negotiate. A $4,000 drainage fix rarely adds $4,000 to the sale price, but a wet subfloor noted in a building and pest report routinely costs a seller far more than that in a price reduction, because the buyer prices in the worst case and their solicitor advises them to. The return on drainage before a sale is defensive, and on a bad enough problem it is the best money you will spend in the campaign.
Do I have to disclose drainage problems when selling a Queensland house?
Queensland has had a mandatory seller disclosure regime since 1 August 2025, and sellers must give buyers a disclosure statement with prescribed certificates before the contract is signed. That regime is largely about title, encumbrances, rates and notices rather than a general confession of every defect, so it does not by itself force you to write down that the back yard gets boggy. What it does not do is protect you from misleading conduct if you actively conceal a known problem or answer a direct question dishonestly. The safe path is simple: fix it, keep the invoice, and hand the paperwork over as evidence rather than hoping nobody looks.
Will a building and pest inspection pick up bad drainage?
Yes, and it is one of the first things a good inspector looks for, because water is what causes most of the defects they are hired to find. They will check whether the ground falls away from the house, whether downpipes actually connect to a stormwater line or just spill onto the ground, whether the subfloor is damp, and whether there is any staining, movement or termite conducive condition around the perimeter. In Toowoomba’s black cracking clay an inspector will also be alert to slab or footing movement caused by moisture change, because the soil shrinks and swells dramatically. Poor drainage is not a subtle finding. It shows up in the report in plain language.
What drainage work is worth doing before I list?
Deal with anything that will appear in a report or be obvious at an open home, and leave the rest. Worth doing: connect any downpipes that are discharging onto the ground, clear and camera a stormwater line that is known to back up, and fix ponding or a boggy patch that will not have dried out by inspection day. Usually not worth doing right before a sale: a full ag drain system on a yard that only gets wet in an exceptional storm, or a detention tank that is not required by an approval. The test is whether a buyer or inspector will see it in the next few weeks, not whether it is theoretically ideal.
How much should I budget for pre-sale drainage in Toowoomba?
Most pre-sale drainage jobs are modest. Re-piping loose downpipes into an existing stormwater line runs a few hundred dollars to about $1,500. A camera inspection is $220 to $450 and a blocked drain clear is $350 to $900. A spoon drain or swale to stop a wet patch is $60 to $130 a lineal metre. Where it gets bigger is a full stormwater connection at $2,500 to $6,000 or an ag drain system at $80 to $140 a lineal metre. A typical tidy-up before listing lands between $1,200 and $4,000. Compare that against what a buyer will knock off once damp is in a report and the maths usually makes itself.
Listing soon and not sure what to fix?
We will look at it honestly and tell you which jobs matter before an inspection and which ones you can leave alone.