Tree Roots and Blocked Drains in Sydney: The Hidden Plumbing Problem Beneath Your Garden

Most of the blocked drains we clear in the Sutherland Shire come back to one thing: tree roots. In the older, leafy streets around Kirrawee, Gymea, Sylvania and Cronulla, where terracotta pipes still run under driveways, lawns and garden beds, roots in the pipe are a weekly job for us, not a rare one.

You don’t need a big tree in your own yard for it to happen. Fine root hairs from a street tree, a neighbour’s tree, or a shrub two blocks away will track moisture and nutrients, find a hairline crack in the pipe, and work their way in. From there it turns into a blocked sewer or a stormwater problem. If you want to plan around it, we’ve put together a guide on the trees to avoid near your drains.

Why roots get into your pipes (and why terracotta makes it worse)

Roots are looking for water, and an old, leaking pipe is the easiest water source in the yard. Terracotta joints are the usual culprit. They’re porous, they go brittle with age, and over the years they shift and crack. Every crack leaks a little water into the soil around it.

The roots follow that moisture straight to the pipe. They start as fine filaments through a crack or a loose joint, then thicken up into a tangled mass inside the line. Once they’re in, here’s what they do:

• Slow the water flow: the drain runs sluggish long before it stops.
• Catch everything: toilet paper, grease and debris snag on the roots and build up.
• Split the pipe wider: as they grow they lever the cracks further apart.
• Cause the backup: eventually you get a full blockage, or the pipe collapses.

It’s why so many older homes around the Shire need either regular clearing or a proper pipe relining to keep the drains running.

Cutting the tree down usually isn’t the answer

People are often told the fix is to cut the tree down and kill the roots. Most of the time that’s the wrong call, and it can cause a bigger problem than the blockage.

When roots are drawing water around a cracked pipe, they’re also holding the surrounding soil together. Take the tree out suddenly and that ground can waterlog, go soft and start to subside, especially where effluent has been leaking into the soil for years. The roots already inside the pipe don’t disappear either. So you can lose the tree and still have the blockage, plus a patch of unstable ground over your pipe.

We’d rather look at the actual pipe first, then talk you through whether the tree even needs to come out.

How we find the blockage without digging up your yard

CCTV drain camera

We run a high-resolution camera down the drain and look at it on the screen. That tells us three things straight away: whether it’s roots, what condition the pipe is in, and exactly where the intrusion is. No guessing, no digging test holes to find the problem.

It also means we can plan the cheapest safe fix rather than the biggest one, and if a neighbour’s tree turns out to be the cause, we’ve got the footage to prove it.

How we clear the roots (and why we skip the chemicals)

Hydro jetting with a root-cutting head

We use high-pressure water jetting with a specialised root-cutting nozzle. The rotating head slices through the root mass and flushes it out of the pipe, no chemicals, and no damage to the pipe wall. What you get out of it:

• Environmentally safe: it’s water, not poison going into the ground.
• Safe on the pipe: it works on terracotta, PVC and earthenware alike.
• Immediate: the flow comes back the same visit.
• Checked on camera: we run the CCTV again afterwards to confirm it’s clear.

Why we avoid chemical root killers

Foaming root killers from the hardware store look like an easy fix, but they don’t do much for you in the long run:

• They don’t clear the blockage: they only slow the regrowth, so the mass is still sitting in your pipe.
• They can attack old pipe materials over time.
• They’re hard on soil biology and groundwater.
• They do nothing about the crack that let the roots in.

They’re a short-term band-aid at best. If you suspect roots have already got into your pipes, the sooner you have it looked at, the less it usually costs to sort out.

Are root barriers worth it?

Root barriers are plastic or metal sheets set in the ground between the tree and the plumbing to steer the roots away. In theory they help. In practice we see them fall short more often than not:

• They don’t touch roots that are already in the pipe.
• Installing them is disruptive and not cheap.
• Roots often just grow under or around them.
• They only really work if they go in before there’s a problem.

Better than nothing on a healthy line, but not the fix if your pipes are already breached.

The permanent fix: pipe relining

If a pipe keeps getting roots in it, it’s only a matter of time before it collapses or needs digging up, unless you reline it. Relining sets a new watertight liner inside your existing pipe, with no joints for roots to get through, and we do it in-house rather than subcontracting it out. Here’s what that gets you:

• Roots stay out: the new liner has no joints or cracks for them to re-enter through.
• Stronger pipe: it reinforces the weak, cracked section.
• No digging: it goes in through existing access points, so your driveway and garden stay put.
• Cheaper than replacement: far less than excavating and laying new pipe.
• Usually done in a day, with minimal mess.

If you’re on a tree-lined Shire street or your home is on older infrastructure, relining is about the most reliable thing you can do for your drains.

➡️ Learn more about pipe relining and how it works

Whose tree is it? Roots and liability in NSW

Plenty of the blocked drains we see are caused by a neighbour’s tree, and the first question is always who pays.

In NSW it generally comes down to where the pipe sits and where the tree came from. If the damaged pipe is on your land, you’re usually the one responsible for it, even when the tree isn’t yours. If a neighbour has been negligent about a known risk, you may have grounds to seek compensation. That’s a legal question rather than a plumbing one, so it’s worth getting advice, and often worth a straight conversation with the neighbour first.

What we can do is give you the evidence: clear CCTV footage and a written report showing where the roots are and what damage they’ve done.

➡️ Contact us for a CCTV inspection or root damage report

Sydney Water also has a useful rundown on tree roots in sewer pipes if you want to read further.

The short version for Shire homeowners

Don’t wave off the early signs: a gurgling drain, a toilet that’s slow to clear, or water pooling in the yard. Nine times out of ten that’s the first hint of roots in the line, and left alone it turns into an excavation or a full failure that costs a lot more to fix.

At The Blocked Drain Guys we put the camera down first, clear the roots with the jetter, and reline the pipe if it needs it, so the problem’s actually gone rather than back next season. If your drains are showing any of those signs, give us a call and we’ll take a look.