Common Drainage Problems in Older Homes

Australia’s older homes are full of character, from weatherboard cottages in country towns to grand terraces in Sydney and Melbourne’s historic suburbs. These homes often have craftsmanship and architectural styles you can’t find in modern builds. But behind the heritage features and period details lies a hidden truth—many of these properties have ageing infrastructure, particularly when it comes to plumbing and drainage systems.

As homes age, their drainage systems are worn out from decades of use. Materials that were once standard—clay, galvanised steel or cast iron—are now known to deteriorate over time. Add to that the impact of shifting soil, invasive tree roots, heavy rainfall and increased water usage from modern appliances and it’s easy to see why drainage issues are so common in older homes.

If you live in or are buying an older property, it’s worth knowing the signs of potential drainage problems before they become major and expensive repairs. Drainage failures can lead to unpleasant odours, water damage and even structural issues. In fact common plumbing problems like blocked drains and corroded pipes are often the root cause of these drainage issues in Australia’s older homes. In this article we explore the most common drainage issues in older properties—and what you can do to fix them before they become a headache.

1. Tree Roots in Pipes

Tree root intrusion is the number one cause of blocked drains in older homes. That lovely old gum tree or shady jacaranda out the front might be putting serious pressure underground.

Older pipes, especially those made from clay or terracotta, are prone to cracks and loose joints—perfect entry points for tree roots. Once inside, the roots grow fast, causing blockages and sometimes breaking the pipes completely.

Look out for:

• Slow draining sinks or toilets
• Gurgling noises in the plumbing
• Overflowing or smelly outdoor drains

What to do:

A plumber can do a CCTV drain inspection to confirm root damage. Clearing roots with a high pressure water jet or replacing sections of pipe may be required. In some cases pipe relining can reinforce damaged sections without digging up your garden.

2. Collapsed or Cracked Pipes

Decades of use, ground movement or heavy traffic above can cause pipes to crack or even collapse. Galvanised steel and clay pipes—common before the 1970s—are especially prone to this.

Watch for:

• Repeated drain blockages
• Wet or sunken patches in the garden
• Unpleasant smells outdoors

What to do:

If a pipe has collapsed, replacement or relining is the way to go. Today’s plumbing techniques often allow for trenchless repairs, so your lawn and paving won’t need to be dug up.

3. Outdated Drainage Layouts

Older homes weren’t built for modern water usage. Back in the day most homes had one bathroom, no dishwasher and minimal laundry needs. Now with multiple bathrooms, rainwater tanks and high volume appliances outdated drainage systems can quickly become overwhelmed.

Problems might include:

• Incorrect pipe slope
• Inadequate stormwater drainage
• Missing or poorly placed overflow relief gullies (ORGs)

What to do:

A licensed plumber can assess if your drainage setup meets current standards. Upgrades may be required if you’re renovating, adding a second bathroom or experiencing ongoing issues.

4. Blocked Stormwater Drains

Autumn leaves, debris and dirt can quickly block gutters and downpipes especially in older homes where maintenance may have been patchy. Blocked stormwater drains can lead to water pooling around the foundations or leaking into the subfloor.

Signs of a stormwater blockage:

• Overflowing gutters during rain
• Pools of water in the yard or driveway
• Moisture or mould in subfloor spaces

What to do:

Keep gutters and downpipes clean and clear. If water still isn’t draining properly an underground stormwater drain may be blocked or broken. A plumber can clear the blockage or recommend upgrades to improve flow.

5. Improper or Missing Venting

Drainage systems need air to function properly. Without the right venting you may notice gurgling sounds, slow drainage or even sewer smells inside the home.

Many older homes were built with minimal venting and in some cases vents have been blocked or damaged over time.

Warning signs:

• Gurgling drains
• Water levels dropping in toilet bowls or traps
• Sewer odours inside

What to do:

A plumber can fix venting issues and install new vents or air admittance valves.

6. Poor Drainage Around the Footings

If the ground around your home doesn’t slope away or if drainage systems have failed water can collect near the footings. This can lead to rising damp, shifting foundations and even structural damage over time.

Look out for:

• Damp subfloor areas
• Cracks in walls or floors
• Musty smells inside

What to do:

Subsoil drainage systems like French drains or ag pipes can redirect water away from the house. You may also need to regrade the soil or add surface drains to manage runoff better.

7. No Backflow Prevention

Backflow occurs when water flows in the wrong direction and can contaminate your home’s water supply. In older homes especially those with old irrigation systems or rainwater tanks backflow prevention devices may be missing or outdated.

Why it matters:

Backflow is a serious health risk and must meet plumbing codes.

What to do:

Get a licensed plumber to check for backflow risks. They can install or upgrade backflow prevention devices if needed to keep your drinking water safe.

Old Homes Need Plumbing Checks

Old homes have character—but their plumbing systems have secrets. Drainage issues are common and if left unchecked can cause water damage, expensive repairs or structural problems.

If you live in, renovate or buy an old property get a plumbing inspection. Look for a plumber who uses modern diagnostic tools like CCTV drain cameras and can offer solutions like trenchless pipe relining.

With a bit of love your old home can stay functional, safe and comfortable for years to come—without the drama of blocked drains or hidden leaks. Be proactive and you can keep the character of your home and avoid plumbing emergencies. A little thought now will save you a lot of stress later.