Stormwater & drainage

Signs your stormwater is not coping

Most of these get ignored until the rain event that makes them impossible to ignore.

• Water pools against the house and takes days to go. The most important one on this list. Persistent water against footings and slab edges causes damp, movement and eventually damage inside.
• A pit or grate overflows in heavy rain. Either the line downstream is blocked, or the pit cannot take the volume reaching it.
• Downpipes discharge onto the ground or into a pipe that stops. Very common, and it dumps the entire roof area's water right next to the building.
• Water gets under the house or into a garage or subfloor. Often a grading and subsoil drainage problem rather than a pipe problem.
• A section of yard stays boggy long after the rain. Poor fall, compacted or clay soil, or subsoil drainage that has silted up.
• Gurgling or water backing up only during storms. Can indicate stormwater and sewer are connected somewhere they should not be, which is worth finding.
• Retaining walls weeping, or efflorescence and salt staining on brickwork. Water is sitting where it should be draining away.
• Erosion or scour lines across the yard. Water is running over the surface because the drainage is not taking it.

If water is actively entering the building right now, call us. If it is a yard problem that has annoyed you for three winters, the form is fine and you will hear back within 12 hours.

What stormwater work costs

Drainage ranges from clearing one blocked line to re-plumbing the surface water on a whole property. The variables:

• Whether it is a blockage or a design problem. Clearing a silted line is a small job. A property where the drainage was never adequate is a bigger conversation.
• How much new pipe and how many pits are needed.
• What has to be excavated and put back. Trenching across lawn is straightforward. Across paving, concrete or established garden is not.
• Where the water can legally go. This is the constraint people do not expect. There has to be a lawful discharge point, and on some blocks, especially where the land falls away from the street, that is the hard part of the job.
• The site. Steep blocks, rock, and high water table near the coast all change the work.
• Whether council approval is involved. Some drainage work does need it, particularly anything affecting a neighbour or a public drainage system.

We will tell you what has to be done and what is optional. On drainage there is nearly always a version that fixes the urgent problem now and a fuller version that fixes the whole system, and you should get to choose between them.

Stormwater in Sydney's north: three very different problems

Drainage is the plumbing people leave longest, because for most of the year nothing is wrong. Then a big storm arrives and the cost of having left it becomes obvious. What is actually going wrong depends a lot on where you live.

Clay soil and flat ground in The Hills

Reactive clay soils through Castle Hill, Kellyville, Baulkham Hills and the newer estates do not let water through easily, so surface water sits rather than soaking away. Large modern homes on those blocks also mean a lot of roof area and paving generating runoff, with less soft ground left to absorb it. When the stormwater system is undersized or partly blocked, water backs up and finds the lowest point, which is often a garage, an alfresco area or the slab edge.

Rock and steep gullies on the North Shore

Across Wahroonga, Turramurra, Pymble, Gordon, Lindfield and Hornsby, sandstone close to the surface means water travels over rock rather than into it, and steep gullied blocks concentrate it fast. Houses built into a slope receive water from uphill, so the job is usually about intercepting flow above the building and giving it a proper path around and away, plus subsoil drainage behind retaining walls. Trenching in rock is also its own consideration and it affects both the method and the price.

Sand, high water table and salt on the Northern Beaches

The low-lying areas around Dee Why, Collaroy, Narrabeen and the flats near the lagoons have their own problem: a high water table means the ground is already holding water, so it has limited capacity to take more, and drainage lines can silt up with sand. On the steep escarpment blocks at Avalon, Bilgola, Whale Beach and Seaforth it is the opposite issue, water moving fast down a slope with a difficult discharge point at the bottom. Salt air also shortens the life of metal drainage components, so we specify accordingly.

The two checks worth doing yourself

Next time it rains properly, put a coat on and go outside. Watch where the water actually goes. Then look at each downpipe and see whether it enters a drain or just ends near the wall. Those two observations tell a plumber more than any description after the fact, and they are the fastest route to a sensible quote.

Call Luke on 0423 213 079 or Zach on 0402 273 744, or send the form and we will come back to you within 12 hours.