A blocked kitchen drain is annoying enough on its own. But every so often, a plumber turns up to a routine callout and finds something that explains why the problem never really went away, no matter how many times it was “fixed.” That’s exactly what happened on a recent job in Midvale, where a kitchen sink had been draining slower and slower for weeks before backing up completely.
The homeowner had tried the usual things: a plunger, some drain cleaner, even a hand auger borrowed from a neighbour. Nothing worked for long. The real issue turned out to be hiding in plain sight, buried under a concrete path laid during a previous renovation.
What a Buried Gully Trap Actually Is (And Why It Causes Blockages)
A gully trap is the outdoor fitting that sits at the point where your kitchen or laundry wastewater exits the house and joins the main sewer line. It’s designed to vent the system, catch overflow, and give easy access if something needs clearing. When everything is working properly, you’d barely notice it. It’s usually a small grated pit sitting flush with the ground near an external wall.
Problems start when that gully gets covered over. It happens more often than people think, usually during landscaping, paving, or a driveway extension, when whoever poured the concrete either didn’t know the gully was there or assumed it wasn’t needed. Once it’s sealed under a slab, the venting function is gone and any blockage downstream has nowhere to overflow to safely. Instead, it backs up into the house, usually through the lowest or most vulnerable fixture, which is often the kitchen sink.
This is one of the first things a Perth plumber for blocked kitchen drains and gully traps will check when a blockage keeps returning despite repeated clearing. If there’s no visible gully outside, that’s a strong clue something has been built over.
Signs Your Gully Might Be Buried or Blocked
A few warning signs tend to show up before things get as bad as a full backup:
- Gurgling sounds from the kitchen sink or laundry trough
- Water draining noticeably slower than it used to
- Odd smells near the kitchen, especially after the sink is used
- No visible gully riser or grate anywhere along the exterior wall near the kitchen
Any one of these on its own might not mean much. Together, especially in an older home or one that’s had recent paving or renovation work, they’re worth getting checked out.
How the Midvale Job Was Diagnosed
With no gully visible from the outside, the first step was a camera inspection run from the internal kitchen drain. This let the technician trace the line and pinpoint roughly where the gully should have been sitting, well before any concrete needed to be broken up.
Once the location was confirmed, it became clear the gully hadn’t been removed or relocated during the earlier renovation. It had simply been paved straight over, with the concrete poured flush across the top of it. No riser, no access point, nothing left exposed at all.
The Fix
From there, the job came down to a few careful steps:
- Breaking out a section of concrete directly above the gully’s location, sized to avoid unnecessary damage to the surrounding path
- Excavating down to expose the gully trap itself
- Reinstating it to the correct height with proper grated access, in line with plumbing standards
- Flushing and clearing the length of drain to remove the buildup that had caused the original blockage
- Testing the kitchen sink and laundry drainage to confirm everything was flowing normally again
Once the gully was back in place and accessible, the kitchen drain cleared and stayed clear, since the actual venting problem had been resolved rather than just masked.
Why This Matters for Other Perth Homeowners
This kind of issue is more common than it should be, particularly in homes that have had paving, driveway work, or landscaping done without a plumber checking what’s underneath first. It’s an easy mistake to make and an expensive one to leave unresolved, since ongoing blockages can lead to water damage, odour problems, and in some cases, damage to the drain line itself from constant pressure.
If a kitchen drain keeps blocking despite regular clearing, or there’s no obvious gully visible outside near the kitchen, it’s worth having someone take a proper look before assuming it’s just a stubborn clog.
Cases like this Midvale job are a good reminder that persistent drain issues are rarely random. If your kitchen sink is draining slowly, gurgling, or backing up with no clear cause, it’s worth getting a plumber to inspect the line properly rather than continuing to treat the symptoms.