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 onsite wastewater management system (OWMS) such as a septic tank, composting toilet or secondary treatment system.
How to manage your onsite 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 construct, install or alter your system
You need a permit from the local council to construct or install a new onsite wastewater management system that can treat up to 5,000 litres daily.
You also need a council permit to alter a system’s construction or design. This includes changes that increase the system's flow or load. Read more about council permits.
Larger systems require an EPA licence to install and operate. Read more about licences.
Maintaining your system
If you own or occupy (such as rent) a property with an onsite wastewater management system, you have legal obligations. This includes operating and maintaining the system so that it doesn’t cause risks to human health or the environment. Read about these obligations.
The general environmental duty (GED) also applies. The GED requires you to manage your onsite wastewater management system to reduce the risk of harm to the environment or human health.
How to keep your system working well
Maintain your system regularly
- Make sure your system can be easily accessed
- Maintain the system regularly. Keep all maintenance record- your council can request to see them
- Use licensed plumbers to check if your system needs cleaning and unblocking
- Desludge the system every three to five years. How often depends on how much the system is used
- Maintain the disinfection chamber. This chamber uses chlorine to disinfect the treated water. Chlorine tablets must be fitted to the dispenser in the right way. If fitted with UV disinfection, UV light tubes must be cleaned regularly
- Have an accredited servicing agent install an alarm to warn you of breakdowns
- Don’t drive vehicles over any part of the system
- Don’t allow stormwater to discharge into the onsite system 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
- Follow any local council maintenance requirements.
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.
Keep bacteria working well
Not all bacteria are harmful. Some of the bacteria in your onsite wastewater management system converts your waste to liquid and gas.
- 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.
Avoid powerful chemicals
- Powerful bleaches, whiteners, nappy soakers, spot removers or disinfectants can impact how well your system works. Try to avoid using them.
Reduce the amount of wastewater you produce
- Install water saving fittings
- Take showers instead of baths
- Wash only full loads of clothes.
Avoid overloading your system
- Space out your water use
- 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 onsite wastewater management system for signs of failure, especially older systems.
- Owners and occupiers, including renters, have a legal obligation to report system failures to the local council.
- You must take steps to address any issues as soon as possible. Warning signs include:
- foul smells coming from or near the system
- slow running toilets or drains
- full or blocked grease trap
- wastewater runoff from the disposal area
- wastewater pooling on the disposal field's surface.
More help for managing your onsite wastewater management system
- Code of practice – Onsite wastewater management (publication 891)
- Victorian land capability assessment framework, Municipal Association of Victoria
- EPA has worked with the City of Casey through the OPLE program to develop a video on maintaining septic systems under 5000L.
- Contact your local council for more information.
Read more about wastewater
Onsite wastewater treatment systems with valid certificates
Requirements for owners and occupier of land with an onsite wastewater management system
Reviewed 20 December 2022