What is going on under Belmont
Belmont is one of the older established parts of the eastern metro. Much of the housing dates from the two decades after the war, and the drainage under it is of that vintage too: vitrified clay sewer laterals, laid in short lengths, jointed every metre or so.
Clay pipe is durable and the joints are the weak point. They weep slightly, and moisture in otherwise dry ground is exactly what a tree root looks for. Belmont has plenty of those — mature street trees along the older grid, and the figs, poplars and liquidambars that were planted in back yards through the sixties and seventies.
Once roots are into a joint, they fan out inside the pipe and catch everything that passes. The blockage is the symptom. The joint is the cause.
Infill has added load
Belmont has been subdivided hard. A lot of the original quarter-acre blocks now carry two or three dwellings, and in many cases the rear lots connect into the same lateral that served one house in 1962.
That matters in two ways. More flow through a line that already has a root mass in it means it blocks sooner. And more dwellings on one lateral means a blockage takes out more than one household at once, which is a poor way to find out the pipe needed relining.
If you are planning a subdivision, get a camera down the existing lateral first.
River flats, not pure sand
Most of metropolitan Perth is deep sand. Belmont, sitting on the Swan River flats near Ascot and Garvey Park, is not uniformly so. Closer to the river the profile carries alluvial silt and clay, which digs heavier than the loose Bassendean sand further out and holds water instead of shedding it.
The practical effect shows up on stormwater. Soakwells rely on ground that drains, and in the heavier sections of Belmont they fill and back up during a solid winter downpour more readily than they would a few suburbs west.
How we deal with it
Clear it first. An electric eel gets the line open and the house functioning, which on a Friday evening with a backed-up toilet is the entire job.
Then, if it is a repeat, a CCTV survey. The camera shows where the roots are entering, how much pipe is affected, whether the line has bellied or cracked, and whether the fault sits on your side of the connection or in the Water Corporation main. That last point decides who pays.
For a fouled rather than plugged line — kitchen waste with decades of fat on the wall is common in this housing — high-pressure jetting scours the bore properly instead of punching a hole through the middle.
Fixing it for good
Relining the affected section with a cured-in-place liner seals the joints without excavating. Replacing the run in PVC is the alternative and is often sensible where the pipe is badly broken or shallow. The footage decides which.
Nearby, Bibra Lake has a different set of problems again. The blocked drains page covers the methods in more detail, and if the water appearing is clean rather than waste, start with leak detection instead.
Frequently asked questions
Why do Belmont drains block so often?
Most of Belmont was built out between the 1950s and the 1970s, which means vitrified clay sewer laterals laid in short jointed sections. Add the mature street trees and back-yard figs that came with that era of housing and you get root intrusion at the joints. Clearing it reopens the line; it does not remove the entry point.
I have just subdivided — does that affect the drainage?
Often yes. Belmont has seen heavy infill, and a rear lot commonly connects into an existing lateral that was sized and laid for one house. An old clay line carrying two dwellings blocks sooner, and anything that was marginal before subdivision becomes a recurring problem afterwards. A CCTV survey before you build is cheap compared to fixing it later.
Is the ground in Belmont different to the rest of Perth?
Parts of it are. Belmont sits on the Swan River flats, and closer to the river the profile carries alluvial silt and clay rather than the free-draining sand you find further west. That makes excavation a bit heavier than a typical coastal-plain dig, and it means stormwater does not soak away as readily.