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# What Homebuyers Need to Know About Septic Tank Systems

By ali abbas / July 14, 2025

If the home you are considering buying isn’t connected to the mains sewer, you’re likely dealing with a septic setup. That might sound complicated at first, but once you understand how septic tank systems work, what maintenance involves, and how to spot warning signs, they’re surprisingly easy to live with.

Plenty of Australians live on blocks where wastewater is managed on-site with the help of several types of septic tank systems. Here’s what to know before signing the contract of sale.

## How the Tank Works

When there’s no sewer connection, waste still needs to be collected, separated, treated and safely dispersed. Septic tank systems do so by sending wastewater into an underground tank, where solids settle and liquids pass through to a trench or absorption field.

Most residential properties rely on natural bacterial digestion and gravity. Once installed, it’s largely hands-off, but only if the conditions are right and the system’s been designed to match the site. Some newer systems also include filtration stages, effluent pumps, or aeration zones to help reduce environmental impact and improve performance.

Understanding whether your prospective home relies on a basic or more advanced system helps you prepare for what kind of maintenance and servicing may be required. It also affects future upgrades or modifications to the property—especially if you plan to renovate or expand.

## What to Check About the Land

Before anything is installed, the property needs to be assessed. Soil type, slope, drainage, and distances from buildings, boundaries, and water sources all count. Some blocks just don’t meet approval standards or would require a more advanced system to compensate for limited space or poor drainage.

If you’re buying a property with a tank already in place, check that it was installed with council approval. Ask if the land has ever had issues with drainage or soakage, as these are the kinds of details that can cost you down the line if they’re missed early.

It’s also worth reviewing the property’s site plan, including any permits or records of environmental assessments. These documents can show whether the system complies with local health and environmental standards and if the disposal area is still functioning as intended.

## How to Look After It

Routine care is simple but not optional. Stick to flushing only human waste and toilet paper. Household cleaners, oils, and hygiene products can throw off the bacterial balance and cause blockages. Avoid tipping food waste or grease down the drain since septic tank systems aren’t built to cope with that.

Most households will need to pump out the tank every 3 to 5 years, depending on usage and size. If that sounds infrequent, keep in mind that early signs of trouble often show up only after the system’s been under strain for a while.

It’s also recommended to spread out water usage during the day, rather than running all appliances at once. Washing multiple loads of laundry or running the dishwasher and shower at the same time can flood the system and reduce its ability to treat waste effectively.

## Early Signs of a Problem

There’s no warning light when a septic system starts to fail. Instead, you’ll usually notice soft, wet patches near the disposal area, slow drains, unpleasant smells, or strange gurgling sounds from toilets or sinks.

These systems are buried and easy to forget about until something’s off. If you’re looking at a house with a system already installed, ask for service records and whether repairs were ever needed. A professional inspection is a small cost compared to what it could prevent.

Even minor indicators, such as grass growing faster or greener in one part of the yard, could be a sign that wastewater is escaping where it shouldn’t. Pay attention to any signs of backflow or moisture build-up, especially in periods of heavy rain.

## Which System Fits Where

Not every property can use the same design. Some types of septic tank systems rely solely on gravity and natural soil filtration, while others use aeration or pump-assisted treatment to manage flow and improve water quality. More complex setups often suit smaller lots or difficult soil conditions.

The tank itself is also important. Pre-fabricated concrete tanks are common because they’re long-lasting, watertight, and low-risk during pump-out. Fibreglass or poly tanks may be used in certain applications but need to be installed with care to avoid shifting or cracking.

Choosing the right system also means thinking long-term. Are you planning to install a granny flat or increase the number of bedrooms? The tank’s capacity and the dispersal area need to be designed with future demand in mind.

## What to Ask Before You Commit

You don’t need to be a wastewater expert, but you do need to ask the right questions. What type of tank is installed? Has it been regularly maintained? Is the system appropriate for the site, and has the property had any drainage issues?

Ask about local regulations, especially if you plan to change the use of the land. Council rules around septic tank systems can vary widely, and approvals may be required for upgrades or extensions.

If you’d like advice on tank capacity, land suitability, or installation options, get in touch with a wastewater specialist in your local area who can walk you through the details of septic tank systems and help you choose one that works for your property.

Also Read: 7 Simple Ways to Elevate Your Home Inside and Out

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