Coogee drain dig-up: tree root damage

Midweek call from a strata manager on Mount Street in Coogee. The main drain at a 1930s apartment block had been slow for months, and over the last few weeks it had stopped draining altogether. They had already tried drain cleaner twice with no result.

CCTV diagnosis: tree roots blocking the line

We set up the RIDGID SeeSnake CCTV camera and ran it through the line. It did not take long to find the problem. Tree roots had pushed through the joints in the old terracotta pipe, filling the bore. The pipe itself was cracked in multiple places. This was not a blockage that jetting would fix permanently. The pipe was too far gone.

Why this job needed a full dig-up

When tree roots enter a drain through a cracked joint, high-pressure jetting can cut through the root mass and restore flow. Norton Plumbing does that regularly across the Eastern Suburbs, and for many properties it is the right first step.

But when the pipe itself is cracked, collapsed, or degraded beyond a single entry point, jetting is a temporary fix. The roots come back because the openings are still there. In this case, the old terracotta had multiple fractures and the pipe wall was breaking apart. The only permanent solution was to dig down, remove the damaged section, and replace it. For more on how tree roots get into Eastern Suburbs drains in the first place, read our detailed guide: Tree roots in old clay drains: the Eastern Suburbs problem that never goes away.

The dig-up and pipe replacement

Greg and I opened up the ground beside the building to expose the pipe run. The old clay section came out in pieces. Some of it crumbled as we pulled it. After 90-plus years underground, the terracotta had reached the end of its working life.

We cleared the trench, laid new PVC drainage pipe, connected the junctions, and backfilled. The new pipe is smooth-bore with sealed joints, so there are no entry points for roots.

What we found underground

The root mass was dense enough that it had completely stopped flow. The roots had entered through at least three separate joint failures along the pipe run. The terracotta was original to the building, likely installed when the block was built in the 1930s.

This is not unusual for older apartment blocks in Coogee, Randwick, Maroubra, and the Eastern Suburbs. Buildings constructed before the 1980s typically have terracotta clay drainage. The joints between pipe sections were bedded in sand-cement, which breaks down over decades of ground movement and moisture. Once a joint opens, roots find it.

Signs your drain needs replacing, not just clearing

Not every blocked drain needs a dig-up. Most do not. But these patterns suggest the pipe itself is the problem, not just what is growing inside it:

• The same drain blocks repeatedly. Jetting or clearing only buys a few months before it returns. The roots keep coming back because the pipe still has openings.
• CCTV shows cracks or collapse in the pipe wall. Not just root entry at a single joint, but structural damage to the pipe itself.
• The pipe is original terracotta in a building constructed before the 1970s. It has never been relined or replaced, and the joints have been degrading for decades.
• Multiple sections of the same run are affected. Not just one entry point, but damage along the length of the pipe.

If you are seeing the first sign, a CCTV drain inspection is the next step. The camera shows exactly what condition the pipe is in, where the damage is, and whether a targeted repair or a full replacement is the better option.

Old terracotta drains in Eastern Suburbs apartment blocks

Most of Sydney's Eastern Suburbs was built between the 1920s and 1960s. The drainage installed during that era was salt-glazed terracotta clay, laid in short sections with sand-cement joints. It was the standard material of the time and it worked well for decades.

The problem is longevity. Clay pipes are brittle. Ground movement, vibration from traffic, and soil expansion and contraction all stress the joints. Tree roots are opportunistic. They follow moisture gradients to the closest water source, and a leaking pipe joint is exactly that.

Apartment blocks carry extra risk because shared drainage runs serve multiple units. One failure point affects every resident connected to that line.

According to Sydney Water's guidelines, property owners are responsible for the drainage between the building and the council connection at the boundary. For strata properties, that maintenance responsibility sits with the owners corporation.

How to reach Norton Plumbing

Norton Plumbing has been diagnosing and replacing failed drains across Sydney's Eastern Suburbs since 2019. We operate from 10/11a-15 Berwick Street, Coogee NSW 2034. Phone: 0477 858 951. I'm Adam Norton, NSW plumbing licence 397768C. We work across Coogee, Bondi, Randwick, Maroubra, Kingsford, and surrounding suburbs. See our blocked drains service page for what a drain inspection involves.