Pressure Sewer Systems

How pressure sewerage systems work

The system will operate like a normal sewage system taking waste from your toilet, sink, shower, bath, dishwasher and washing machine and transferring it to the wastewater treatment plant for processing.

However, pressure sewerage systems differ from conventional gravity systems because they depend on a collection/pump unit located on each connected property, which is connected to a network of pipes along with other pump units in your area. These pipes transfer wastewater to the wastewater (sewer) treatment plant for processing.819 - Inside Pressure Sewer Tank Unit

The grinder pump works in the following way:

  • The pump grinds up any solids in the tank so they can pass through the property discharge line to our main wastewater pipes.
  • The collection tank will store household wastewater until the 'pump-on' level is reached. When this occurs the pump will automatically turn on and pump the wastewater to the main wastewater pipes.
  • When the level of wastewater falls to the 'pump-off' level, the pump will automatically switch off.
  • Typically, a pumping cycle will take one to two minutes, and will occur several times a day.
  • If the pump fails to operate, the level of wastewater will continue to increase until it reaches 'alarm level'. When this happens an alarm will sound and a light will flash on your alarm/ control panel. This level is about one third the total capacity of the tank, so there is still a lot of tank capacity after the alarm has been activated.
  • The alarm may also be activated as a result of power returning after a power service interruption. In all cases the alarm will automatically turn off when the storage level drops below the alarm level. The audible alarm can be switched off by pressing the small button under the control/alarm panel.
  • The standard collection tank has a maximum capacity of about 1100 litres.  The Installation and Maintenance Agreement for the pressure sewer system installed on your property will outline the size of the pump and collection tank.

Parts of the pressure sewerage system

A pressure sewer system is made up of four main components:

819 - Pressure Sewer Arrangement

Collection tank and pump unit
A grinder pump is housed within the collection tank on your property. The collection tank has mechanical and electrical parts. The collection tank is installed underground so that only the lid is visible to allow access for servicing.  

Pump Control Panel or Alarm Box
The pump control panel is a small box containing all the electrical controls for the pump unit as well as the audible and flashing light alarm system (located on top of the box). Sometimes referred to as the alarm box, it has both audible and visual alarms to provide adequate warning when the pump unit needs to be serviced by Council. Power to the pump unit is sourced from your property's electrical switchboard.

Property discharge line
The property discharge line connects the collection tank/pump unit to the boundary kit. This is the line used to discharge wastewater from the property into the pressure sewer main in the street.

Property boundary kit
The boundary kit is the connection point between the property discharge line and the pressure sewer main in the street.  Inside the boundary kit is a one-way valve, isolation valve and inspection or flushing point. These are to:

  • prevent wastewater from Council’s pressure sewer main and other properties discharging back into your house pressure line;
  • isolate the property service from the mains system.   This is used to prevent your sewer pump from discharging into the sewer main enabling repairs and maintenance; and
  • inspect and clean the system if necessary; and
  • allow flushing the system, if required.
  • under no circumstances should you operate these valves.

Other key sanitary on property services that effect the operation of the pressure sewer system are:

Inspection Shaft
The inspection shaft is a plumbing fixture that allows plumbers to inspect and service your property service drain. It is a key fixture for future inspections and maintenance works that may be required on the property. It is important that property owners maintain access to this fixture. The inspection shaft is the responsibility of the property owner.

Overflow Relief Gully – ORG
An overflow relief gully protects the interior of your home or building from sewerage overflow. It is a drain-like fitting located outside the property that is an important part of the plumbing system. In the event of a sewer blockage, the overflow relief gully is designed to release any sewerage overflow away from the interior of the building and outside to a garden or external area. It is important for property owners to keep the overflow relief gully clear and unimpeded at all times. The overflow relief gully is the responsibility of the property owner.

Property Service Drain
The property service drain is the section of gravity pipeline connecting the sewage pipe outlets from the house to the collection tank. The property service drain is the responsibility of the property owner.

Electrical Switchboard
The electrical switchboard is a standard electrical switchboard which connects the property to the power supply system. It will have a connection point and circuit breaker designated to the power supply for the on-property collection tank and pump unit. The associated power and operational costs are the responsibility of the property owner.

What to do if the alarm sounds

When the collection/pump unit alarm sounds it will beep and a red light will come on. If this happens you should:

  1. silence the alarm by pressing the button labelled “Alarm Silence ” under the alarm control panel. Please note that you cannot turn off the red light. It will turn off when the problem has been fixed and the collection/pump unit is working correctly
  2. call Council on 02 6578 7290 (24 hours) to report that the pressure sewer alarm has sounded and the light is still active.  Be sure to give your name, address and telephone number.
  3. Council’s Water and Sewer Group Network Delivery Team will attend the site and clear the blockage or repair the fault.
  4. minimise water going to the system when the alarm is on (or during a power service interruption)
    • Keep showers brief.
    • After taking a bath, leave the plug in, or bucket water onto the lawn.
    • Switch off any drainage (automated or manual) from swimming pools and spas.
    • Do not leave taps running.
    • Avoid using the washing machine unless you can direct the water to a plugged laundry tub (where it can be transferred by bucket onto the garden).
    • Do not use dishwashers.

You can still use the wastewater system. Toilets can still be flushed, and normal kitchen activities can proceed, just minimise water use.

Do not turn off the electricity supply at your electrical distribution board as this may result in wastewater (sewer) overflows.
Do not attempt to repair the unit yourself.

Need to apply for a pressure sewer system installation?

Visit our Pressure Sewer Connections page for a guide on applying for a pressure sewer system installation on your property, or call one of our Customer Service Team for advice.

Related information

  • Pressure Sewer System - Installation and Maintenance Agreement
  • Pressure Sewer System - General Terms and Conditions
  • Pressure Sewer System - Home Owner's Guide
  • POL/26031 Sewer Service Policy
  • Water and Sewer Group – Customer Service Plan
  • Sewer Blockages - Questions and Answers
  • Tree Roots and the Sewer System – Fact Sheet
  • Overflow Relief Gully – Protecting your Home from Sewer Overflows - Fact Sheet