Sewerage Line Cracks: Causes, Risks & Warning Signs

Sewerage line cracks are one of those problems that sound pretty horrific – and yet most property owners don’t even think about what might happen if it occurs at their place. The thing is, when something goes wrong with your sewer line, it tends to go seriously wrong – and yet much of it happens well away from your eyes.

After all, those sewer lines are hidden underground – and they deteriorate very quietly. But as they’re going wrong, they’re:

• Causing damage to your plumbing system
• Creating health risks
• And leading to very expensive repairs if left unchecked.

Let’s try to get our heads around why these cracks form, what risks they pose, and how to spot the early warning signs. If you can log all of that, you can make the difference between a targeted fix and a major, major disruption.

What causes cracks in sewer lines?

Sewer infrastructure is built to last – but that doesn’t mean it’s indestructible. Over time, a combination of environmental and structural pressures can lead to sewer line cracks, even in systems that were originally installed correctly.

The common causes include:

• Tree root intrusion, where roots seek moisture and force their way into joints and weak points
• Ground movement, including soil shifting, subsidence, or erosion
• Ageing pipes, particularly older clay or concrete systems
• Heavy surface loads, such as vehicles or construction activity above the line
• Poor installation or previous repairs that create stress points.

Once a cracked sewer line forms, wastewater can leak into surrounding soil – and then debris can enter the pipe. That’s where deterioration really accelerates, increasing the likelihood of blockages (and worse).

The health & plumbing risks of sewer line damage

Ignoring cracked sewer lines can have serious consequences, both for your plumbing system and the people using the property.

From a plumbing perspective, sewer line damage often leads to:

• Recurring blockages
• Slow drainage
• Foul odours
• Backups that worsen over time.

And in the most severe cases, a broken sewer line can collapse entirely – requiring excavation and replacement rather than pipe relining or targeted repair.

From a health standpoint, leaking wastewater introduces harmful bacteria and pathogens into soil, air, and sometimes even the living spaces. This can contaminate groundwater, attract pests, and expose occupants to very unpleasant – and potentially very dangerous – conditions.

And because these issues develop underground, they often go completely unnoticed … until the symptoms become impossible to ignore.

7 Warning signs of sewer line cracks to look out for

The most effective way to avoid major damage is to recognise the early indicators that something isn’t quite right. We’ve put together the 7 most common warning signs that may point to underlying issues, such as sewer pipe cracks or structural failure.

1. Persistent drain odours

If unpleasant smells linger around drains, yards, or outdoor areas, it may indicate wastewater escaping from a compromised pipe rather than flowing where it should.

2. Frequent or repeated blockages

Blocked drains that return soon after clearing can signal a damaged sewer line, where debris catches on rough edges or enters through cracks.

3. Slow draining across multiple fixtures

When sinks, toilets, and showers drain slowly at the same time, the issue is often deeper in the system rather than at a single outlet.

4. Unexplained wet patches or weirdly lush grass

Sewage leaks may gross you out, but to your lawn, it’s like great fertiliser. Unusually green patches of lawn or damp areas with no obvious water source may indicate leakage below the surface.

5. Gurgling noises in pipes

Air escaping through damaged sections of pipe can cause bubbling or gurgling sounds when water flows through the system.

6. Backups after heavy rain

Rain can saturate surrounding soil and force wastewater back through weak points – making existing sewer line problems suddenly more noticeable.

7. Pest or insect activity near drains

Rodents and insects like drain flies just love moisture and waste. If you notice increased activity around drain areas, that can sometimes be traced back to leaking sewer lines underground.

Why early detection matters

Catching cracks early is the name of the game here – that way, you can target the professional inspection and sewer line repair before damage really escalates. Modern CCTV inspections can pinpoint faults without guesswork, helping plumbers assess the severity and recommend the most appropriate solution.

If left unresolved, small defects can widen, which:

• Allows soil to enter pipes
• Worsens blockages
• Increases the likelihood of collapse.

Take action early, and you’re protecting both your plumbing system and the health of the property’s occupants.

Get expert help before small issues become big ones

Have you noticed any of the 7 warning signs? If so, professional assessment is an extremely good idea! The experienced team at Brisbane Drain Cleaning uses advanced CCTV inspection technology and all of our local experience to locate sewer issues accurately and recommend the solutions that will last.

For fast, honest advice and reliable repairs across the Brisbane Northside, Brisbane Southside, Logan, Moreton Bay, Redland Bay and anywhere across Brisbane, contact Brisbane Drain Cleaning today – and protect your property before minor cracks turn into a major headache.