By Matthew Baring-Gould, Kingscliff-based drainage plumber. Servicing Tweed Heads for 4 years. 5.0 stars across 173 Google reviews. Licensed NSW 383340C and QLD 15036450. ABN 74 605 392 348.
Blocked stormwater at the rear of a Kingscliff property. CCTV found two breaks in the line out to the street (not flow-stopping yet but they will need to be fixed). Bigger issue: the main drain was overloaded and could not cope in heavy rain events, and the strip drain at the laundry entrance was too shallow to handle any real volume. Cleaned gutters as part of the visit and found roof areas needing a roofer. Quote to replace the stormwater to street in twin 100mm DWV PVC.
What the customer called us for
Owner called us out for a blocked stormwater drain at the rear of the property. Water was backing up near the laundry during rain and they could not get on top of the blockages.
What we found when we got there
Two findings. First, CCTV showed two separate breaks in the stormwater line between the house and the street. Neither was fully blocking the flow yet but both would need repair in the near future. Second, and more importantly, the main stormwater line was undersized for the roof catchment, so in a heavy rain event the whole system could not cope regardless of how clean we got the pipes. The strip drain at the laundry entrance was also the wrong spec for the role it was being asked to play: too shallow, not designed for heavy flows.
Why we did it this way
Clearing blockages on an overloaded system is like paying someone to bail out a boat with a bucket when the real problem is the hole. On a Tweed coast property, average annual rainfall is around 1.5m and we regularly get storms dropping 100mm in an hour. If the stormwater main cannot carry that flow, you will get backup every big storm no matter how clean the lines are. The right fix on this one is a straight re-run: twin 100mm DWV PVC from the rear of the property to the street. Cuts the risk of future blockages down to almost zero and gives the roof catchment somewhere to actually go.
What we did on site
- Attended site and investigated the blocked stormwater at the rear of the property.
- Ran CCTV through the line to the street and identified two separate breaks on the left side of the house.
- Located and marked the breaks on the surface.
- Concluded from flow analysis that the main drain was undersized for the catchment.
- Flagged the laundry strip drain as the wrong spec for the role.
- Cleaned out the gutters around the property as part of the visit.
- Assessed the roof for damage and identified areas for a roofer.
- Quoted the re-run of the stormwater to the street in twin 100mm DWV PVC.
The result
Breaks located and marked. Main design problem diagnosed and a proper fix quoted. Owner has photos, surface marks, and a plan to replace the undersized line before the next big wet.
If you have the same issue
If your stormwater backs up in every big rain even after you have cleaned it, the pipes are not the problem. The pipes are the symptom. Get a plumber to CCTV the line AND check the pipe sizing against your roof catchment. If the main is 90mm or a single 100mm trying to carry the whole roof, it will overload every big storm. Call Matty on 0447 188 394 or request a quote.
Customer names and addresses have been withheld. Individual results vary. Drain Masters Plumbing is licensed in NSW (383340C) and QLD (15036450).
Frequently asked
Why twin 100mm PVC instead of a single bigger pipe?
Twin 100mm lines carry more combined flow than a single 100mm, give you redundancy if one blocks, and fit easily in a standard trench with standard fittings. Going to a single 150mm would also work but costs more in materials and digs and loses the redundancy advantage.
What is a strip drain and why can it be the wrong choice?
A strip drain is a shallow linear drain at ground level, usually at a doorway or driveway entrance. They are designed to catch a thin sheet of surface water and lead it into the main stormwater line. They are not designed to catch a sudden volume of water from a roof overflow. If you install a strip drain where you need a proper channel grate with real depth, it overloads immediately in heavy rain.
If the breaks are not stopping the flow, why fix them now?
A small break today is a big break in 2-3 years. Ground movement, root growth, and water erosion all make small breaks bigger over time. Once a break hits a certain size, the pipe collapses and you are looking at a sinkhole or a slab failure, not a repair. Fixing while the breaks are small is always cheaper than fixing after they fail.
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