Sewage is wastewater that comes from toilets, bathrooms, kitchens and laundries.

Most sewage goes through Victoria’s sewerage systems for treatment.

Sometimes it’s not practical, or possible, to connect to the existing sewerage system. In that case you can manage sewage using an on-site wastewater management system (OWMS) such as a septic tank system, composting toilet or sand filter.

How to manage your sewerage system the right way

Poorly installed or maintained systems can be a risk to human health and the environment. This is especially true of older systems. Risks can include:

  • polluted drinking water
  • land and waterway contamination
  • offensive smells.

How to build, install or change your OWMS

You need a local council permit to build or install an OWMS that can treat up to 5,000 litres daily. This is most home OWMSs. You need an EPA licence to install and run an OWMS that can treat more than 5,000 litres dailly.

You need a local council permit to change an OWMS's construction or design. This includes changes that increase the system's flow or load.

How to maintain your OWMS 

  • Ensure you can access your system easily.
  • Use licensed plumbers to assess whether your system needs cleaning and unblocking. 
  • Desludge the septic pump every three to five years. How often depends on level of system use.
  • Have the system's mechanics serviced every three months. Record all system maintenance. 
  • Have an accredited servicing agent install an alarm to warn you of breakdowns. 
  • Maintain the disinfection chamber. This chamber uses chlorine to get rid of bacteria. Chlorine tablets must be  fitted to the dispenser in the right way. UV light tubes must  be cleaned often.
  • Don’t drive vehicles over any part of the system. 
  • Don’t allow stormwater to discharge into the septic tank or over the disposal/drain field. 
  • Don’t cover the tank or drain field. 
  • Don’t place non-biodegradable items or rubbish into the system. Bacteria and other organisms can't break down these items or rubbish.
  • Make sure you follow any local council maintenance requirements.

How to keep your OWMS working well

To reduce sludge build up in the tank:

  • scrape all dishes to remove fats and grease before washing
  • don't put solids in the system
  • don't use a food waste disposal unit unless your system can carry the extra load
  • don't put hygiene products in the system. For example, sanitary napkins and tissues.

Not all bacteria is harmful. Some of the bacteria in your OWMS converts your input to liquid and gas. To keep bacteria working well:

  • use biodegradable soaps and detergents that are low in phosphate. Phosphates feed algae that pollute waterways.
  • in dispersive soil areas, use detergents that are low in sodium
  • use the right amount of detergents
  • don't put chemicals or paint down your drains.

Powerful bleaches, whiteners, nappy soakers, spot removers or disinfectants can impact how well your system works. Try to avoid using them.

To reduce the amount of wastewater you produce:

  • install water saving fittings
  • take showers instead of baths
  • wash only full loads of clothes.

To avoid overloading your OWMS, space out your water use. For example:

  • Don't do all your washing in one day.
  • Don't run your dishwasher and washing machine at the same time.

How to deal with system failures

You must monitor your system for potential failures, especially older systems. This means watching for warning signs, including:

  • foul smells coming from or near the system
  • slow running toilets or drains
  • full or blocked grease trap
  • wastewater run off from the disposal area
  • wastewater pooling on the absorption field's surface.

You must take steps to address any issues, even if only on your property.

How you can use wastewater from your septic tank system

Septic tank systems can treat wastewater to meet three standards: 

  • Primary quality: safe to go into soil. 
  • Secondary quality: suitable for surface irrigation use, but don’t put directly into soil. 
  • Advanced secondary quality: suitable for use in your toilet or washing machine. Also suitable for surface and underground irrigation. 

More help for managing your OWMS

Code of practice – Onsite wastewater management (publication 891)

Victorian land capability assessment framework, Municipal Association of Victoria

Maintaining septic systems under 5000L video

Contact your local council for more information.

Read more about wastewater

About wastewater

About greywater

Onsite wastewater treatment systems with valid certificates

Regulatory framework and approval process for onsite wastewater treatment systems

Wastewater guidance for industry

Reviewed 16 September 2020