Types of sanitary drainage systems

Gravity systems

Gravity sewerage systems are the traditional method of sewage disposal. These systems take advantage of the natural slope of the ground to collect wastewater, take it away from the property and allow it to flow to the authority sewerage network. The network system transports the wastewater to the treatment plant.

Gravity systems are used in areas where the water table is low and the land is not prone to flooding.

While gravity systems are the most common there are other systems that you should be aware of.

Graphic of a house showing pipe using the natural slope to take wastewater away from the house. This pipe and the street drainage both enter the sewer main.
Open icon Low Pressure Systems

Low-pressure sewer systems are a low-head pressure wastewater collection and treatment system. They are an alternative to gravity sewer systems or septic tanks.

A low-pressure sewer system consists of an interceptor tank and a chamber unit, which houses a small, submersible electrical pump. The tank is installed below ground, much like a septic tank. Substantial organic waste treatment occurs in the interceptor tank. The liquid in the tank, or effluent, is pumped automatically through a small pressure line that transports it to a wastewater plant for treatment.

Graphic of a low pressure system shows that pipes pass through the below ground pump unit. Effluent is discharged from these through pipes that enter the wastewater plant. A pump control panel is fitted to the house.
Open icon Vacuum systems

The vacuum sewage system is an alternative method to a conventional gravity system. It is generally used in areas that feature water charged ground, reclaimed ground, flat areas and in seasonal areas such as recreation areas and camping sites.

A vacuum system needs a central vacuum station, with vacuum pumps, collection chamber, discharge pumps and associated controls. The various sewage fittings are each connected to the system via a vacuum valve.

It operates on electricity so it requires an additional power supply in case of a power failure.

Graphic of a vacuum system shows that the collection chamber with vacuum pump is housed below ground and beyond the boundary of the property.