A septic system with a pump chamber for overflow is designed for sites where gravity alone can’t move wastewater efficiently. These systems collect and temporarily store effluent before pumping it to a treatment or disposal area when elevation changes or long distance prevent gravity flow.
Above: Typical Septic Overflow System with Pump Chamber set-up
Although septic tanks are widely understood, the pump chamber is a separate component rather than part of the tank itself. While the two can look similar, they perform different functions. The septic tank provides primary wastewater treatment and contains no pumping equipment. The pump chamber is installed downstream and houses the pumps and controls required to move effluent when gravity flow is not possible. This design is also commonly used for stormwater chambers and drainage applications across residential and commercial developments.
A septic tank with a pump chamber operates as two components working together. After solids settle in the septic tank, partially treated effluent flows into the sewage pump chamber. From there, submersible pumps transfer the liquid to the next stage of treatment or disposal, such as a raised drainfield, sand filter, or irrigation area. Pump operation is regulated by float switches and controllers to ensure controlled, consistent discharge.
This arrangement is typically used when the discharge point sits higher than the tank outlet or where even effluent distribution is required. By separating treatment and pumping, the system operates more reliably, avoids overloading, and is easier to keep compliant with regulatory requirements.
The pump chamber only stores effluent briefly before it is pumped onward. It is purpose-built to manage flow safely and consistently, protecting pumping equipment and supporting overall system performance. Unlike septic tanks, pump chambers are engineered specifically to house submersible pumps, controls, and safety features.
Material selection plays a major role in long-term performance. While fibreglass (FRP) chambers are sometimes used, polyethylene tanks are generally more durable and better suited to buried applications. Polyethylene can flex under soil and groundwater loads without cracking, whereas fibreglass is rigid and more susceptible to fracture or delamination over time. It also offers excellent resistance to wastewater chemicals and corrosive soil conditions without the need for protective coatings.
Polyethylene chambers are lighter, making transport and installation simpler and more cost-effective. Because they are rotationally moulded as single-piece units, they have no seams or joints that can weaken or leak. With minimal maintenance requirements and long service life, polyethylene pump chambers typically deliver lower whole-of-life costs than FRP alternatives, particularly in systems with frequent pump cycling and fluctuating water pressures.
Correct installation is essential for reliable operation. The pump chamber should be positioned downstream of the septic tank to allow natural effluent flow into the chamber. A level, well-compacted base helps prevent settlement, while appropriate backfilling provides even wall support. Venting should be included to prevent gas build-up, and all electrical work for pumps and alarms must be completed by a licensed electrician using waterproof fittings.
Routine maintenance helps ensure safe operation over time. Pumps and float switches should be checked periodically, high-level alarms tested, and the chamber kept free of debris or sludge accumulation. Local councils or environmental authorities may require inspections or certification for new or upgraded systems and installing an AS/NZS 1546.1–compliant pump chamber helps ensure compliance with Australian wastewater performance and safety standards.
For sites where gravity systems are not practical, a septic system with a pump chamber provides a dependable, low-maintenance solution. These systems offer strength and flexibility underground, resistance to corrosion and chemical attack, and straightforward installation while remaining compliant with Australian standards.
Suitable for both residential and commercial use, pump chambers deliver long-term performance across a wide range of on-site wastewater and stormwater applications. Using a dedicated pump chamber instead of placing pumps inside a septic tank improves safety, efficiency, and ease of servicing. With proven designs, durable materials, and flexible configurations, Global Water’s pump chambers provide reliable solutions for demanding site conditions.
Get in touch with our team today to discuss your project and find the best solution for your site.