Everything You Need to Know About Maintaining an Underground Sewage Tank

All sewage tanks exist for the same reason and when designed effectively, will require occasional cleaning and maintenance to remove sludge and waste from the tank. Proper maintenance of an underground tank is essential to ensure efficient operation, prevent overflows, and extend the lifespan of the system. Whether used for residential, commercial, or municipal wastewater management, regular maintenance helps to avoid unpleasant odours, contamination risks, and costly repairs.

In this guide from the tank experts at CSG Composites, we’ll explore how sewage tanks function, the importance of routine maintenance, and the best practices for keeping your system in top condition.

What is a Sewage Tank and How Does it Work?

Firstly, let’s start with the basics. A sewage tank, also referred to as a septic tank system or waste water tank, is an underground structure designed to collect and treat wastewater from toilets, kitchens, laundries, and bathrooms. These tanks are typically constructed from fibreglass or plastic and work by separating solid waste, oils, and grease from the liquid effluent before it is drained into a soakage system or drainage field.

The tank operates through a biological decomposition process, where waste naturally breaks down over time. Inside the tank, wastewater is divided into three layers:

• Top layer – Oils, grease, and floating debris (scum layer)
• Middle layer – Partially treated liquid waste (effluent layer)
• Bottom layer – Heavier solids that sink and form sludge

Without regular maintenance, sludge accumulates, leading to blockages, overflows, and system failure.

What is an Emergency Overflow Tank?

An emergency overflow tank is an additional containment system designed to handle excess wastewater when the main sewage holding tank reaches capacity. These tanks prevent raw sewage from backing up into buildings or overflowing into the surrounding environment.Emergency overflow tanks are particularly useful for properties with high wastewater output, such as industrial sites or large households. They act as a safeguard, ensuring the system continues to operate efficiently even under heavy use.

How to Maintain Your Sewage Tank for Longevity

Regular maintenance is crucial for effective wastewater treatment, preventing system failures and ensuring that your sewage tank remains in top condition and functions efficiently for years. Follow these key maintenance steps:

1. Schedule Regular Pump-Outs

Over time, solid waste accumulates in the tank, which can lead to blockages and overflows. Depending on the tank size and usage, a sewage holding tank should be pumped out at least once a year to prevent sludge build-up, waterborne diseases and reduce risk of tank damage. By following a strict cleaning routine each year, you can protect the tank from clogging and breaking down and ensure efficient wastewater flow. Larger industrial or high-use tanks may require more frequent servicing.

2. Monitor Water Usage

Excessive water entering the septic system can overwhelm the tank, reducing its efficiency and leading to potential overflow. Reduce unnecessary water use by installing water-efficient fixtures, repairing leaks, and spacing out high-water usage activities such as laundry and dishwashing.

3. Avoid Disposing of Harmful Substances

Certain chemicals, such as solvents, oils, grease, and non-biodegradable items, can disrupt the biological breakdown of waste and damage the tank. Where possible, only flush biodegradable waste and avoid pouring harmful chemicals down drains.

4. Check for Signs of Issues

Regularly inspect the tank and surrounding area for warning signs of failure, such as:

• Slow drainage in sinks and toilets
• Unpleasant odours near the tank
• Pooling water or damp ground above the tank
• Gurgling sounds in plumbing systems

If any of these issues arise, arrange for an inspection and servicing immediately.

5. Ensure Proper Ventilation & Access

Keeping the tank lid properly sealed while ensuring adequate ventilation is important for preventing odours and gas build-up. Make sure access points, such as manhole covers, remain secure yet accessible for inspections and servicing.

6. Protect the Drainage Field

The drainage system plays a crucial role in filtering wastewater before it returns to the environment. To keep it functioning properly:

• Avoid parking vehicles or heavy machinery over the area.
• Prevent tree roots from infiltrating pipes and causing blockages.
• Ensure good drainage to prevent waterlogging, which can lead to system failure.

7. Maintain Accurate Service Records

It’s always a good idea to keep a logbook handy to record any services. Keeping records of pump-outs, inspections, and maintenance schedules can help track your tank’s condition and identify potential issues before they become costly problems.

The Importance of Choosing a High-Quality Sewage Tank

Proper maintenance starts with installing a durable, high-quality sewage tank that meets Australian standards. Factors to consider when selecting a tank include:

• Material – Fibreglass and plastic tanks are lightweight, durable, and resistant to corrosion.
• Capacity – Choose a tank size that suits your property’s wastewater needs.
• Ease of installation – A well-designed tank simplifies the setup process and reduces the risk of structural issues.
• Compliance – Ensure the tank meets local council and environmental requirements.

At CSG Composites, we manufacture high-quality underground tanks built for long-term performance. Our fibreglass and plastic tanks are engineered to withstand harsh conditions and provide reliable wastewater storage solutions.

5 Installation Best Practices for Sewage Tanks

To maximise the efficiency and lifespan of your sewage tank, proper tank installation is essential. Consider the following best practices:

1. Site Selection – Choose a location that is easily accessible for maintenance but far enough from water sources to prevent contamination.
2. Proper Ground Preparation – Ensure the ground is level and compacted to prevent shifting or sinking over time.
3. Correct Pipe Connections – All inlet and outlet pipes must be properly sealed to avoid leaks and ensure optimal function.
4. Adequate Ventilation – Proper ventilation is required to allow gases to escape safely and prevent pressure build-up inside the tank.

Secure Lid Installation – A secure but accessible lid ensures safety while allowing for easy maintenance and inspections.

CSG Composites: Supplying Long-Lasting Sewage Tanks

At CSG Composites, we specialise in designing and manufacturing durable and efficient underground sewage tanks. Regardless of the kind of wastewater, our tanks can store underground sewage outflow up to 671 kilolitres. We ensure that our range of underground overflow tanks are built for long-term reliability, easy maintenance and high-capacity wastewater management.

We take pride in providing Australian-made solutions that support effective wastewater management for various industries, from construction to municipal infrastructure.To learn more about our underground sewage tanks and custom manufacturing solutions, contact our team today.