Maintaining your wastewater system

All wastewater systems require maintenance to keep them working effectively. Septic tanks and aerated treatment systems both require emptying or desludging when the sludge fills to halfway up the tank. Failure to remove this sludge will mean that it will overflow into your effluent trenches or irrigation lines and block them, requiring costly replacement of your system.

The main causes of problems with onsite wastewater treatment systems include: 

  • The introduction of too much water into the wastewater system. 
  • Allowing incompatible chemicals and materials to enter the system that then interfere with the operation of your system.       
  • Too many fats and oils getting into the system then clogging up your pipes and disposal system.  

Below are some helpful tips to help reduce load on your onsite wastewater treatment system and on your wallet. 


Tips for inside the home

In the house

  • Repair leaking taps and toilets as soon as possible to reduce the water load on the system. 

  • Only use septic-safe cleaning chemicals in and around the home. Chemicals that contain large amounts of antibacterial compounds can kill the good bugs (e.g. bacteria) that work hard inside the wastewater system to improve the water quality and break down the waste. 

  • Ensure personal care and hygiene products are not flushed down the toilet as they take a long time to break down and can clog components of the wastewater system. 

In the laundry

  • Spread your washing out over the week. This will avoid flooding the system with large amounts of water at one time. 

  • Use low-phosphorous detergents. Phosphorous is a major pollutant of waterways and contributes to algal blooms and environmental degradation. 

  • Ensure you laundry detergents are low in sodium. Sodium can have very negative impacts on the soil and the vegetation in your wastewater disposal area, which are vital to the wastewater system. 

  • Use liquid detergents or highly biodegradable powder detergents to reduce the impact on your wastewater system and the surrounding environment. 

  • Avoid blockages in the system by installing a lint filter on the washing machine and keeping it clean. 

  • If you have a blocked drain, use boiling water or an electric eel to clear the line, rather than using caustic soda or another chemical that will affect the functioning of the system. 

  • Select a washing machine that rates high on the WELS system for water efficiency (www.waterrating.gov.au). 

  • Wash only full loads. Hand washing of small items saves water. 

In the kitchen

  • Use a sink strainer. This will help to prevent food particles entering the wastewater system and slowing down its function. 

  • Do not pour oils and fats down the sink. They solidify and may block the pipes. Instead, put them into a container such as a milk carton and throw it out with the rubbish. 

  • Wipe grease out of pans and dishes before washing them. 

  • Wash only full loads in the dishwasher. 

  • Install low-flow taps at the sink. 

  • Avoid installing and using a sink garbage disposal unit. 

  • Ensure your dish washing detergents are low in sodium to protect the environment receiving your wastewater. 

  • Avoid using chemical drain cleaners. 

In the bathroom

  • Install a low-flow shower head to conserve water.  

  • A dual flush toilet can significantly reduce the amount of wastewater your system needs to manage. 

  • Minimise the use of harsh cleaners such as bleach and other disinfectants as they can interfere with the good bugs (e.g. bacteria) that help to breakdown the waste. Instead, try baking soda or a very mild detergent solution. 

  • Do not flush anything down the toilet that could clog up the system, i.e. condoms, tampons, cat litter etc. These items will quickly fill up your tank, decreasing its efficiency and making it necessary to pump it out more often. 

  • Verify that the toilet is not leaking by placing a small amount of food dye in the cistern. If you see dye in the toilet bowl within 30 minutes, your cistern is leaking, and you need to contact a licensed plumbing practitioner to have this fixed. 


Tips for outside the home

Around the Septic Tank or Aerated Wastewater Treatment System

You need to know where your treatment system is located, and that service agents or licensed plumbing practitioners can have easy access to it for repairs or servicing. It is very common that septic tanks have been buried and if this is case then you need to find it, dig it up and install “saddles” or “risers” to allow ongoing access. 

  • Avoid planting trees close to your septic tank. The roots could invade the tank and pipes as they grow. 

  • If the alarm on your pump well or package treatment plant is triggered, seek assistance from a licenced plumber or service agent immediately. 

  • Do not connect water outlets such as storm water drains to your septic tank. 

  • Add filters to the outlet of the tank. This can extend the life of your effluent disposal system. 

  • Check the baffle and T-junctions within the tank. If either are damaged, they will need replacement before more damage is done. 

  • Keep the tank clear of vegetation. If the lid of the septic system is broken, ensure it is repaired immediately to avoid storm water invasion. Also, ultraviolet radiation from the sun can have detrimental effects on the functioning of the septic system. 

  • Ensure the septic system is de-sludged every 3-5 years depending on use, by a qualified licensed plumbing practitioner. 

  • Ensure that quarterly servicing of the wastewater system is completed by an adequately qualified service agent (AWTS). 

  • Ensure the tank is sealed and that all air vents are covered with netting or gauze to prevent mosquito and insect access to the tank. 

  • When they are functioning correctly, wastewater systems do not smell. If you detect an odour emanating from your wastewater system, it may be as simple as a pH imbalance in the tank. Try flushing a cup of garden lime down the toilet every day until the odour stops. If the odour does not cease in a two-week period, seek assistance from a licensed plumbing practitioner or service agent.   

Around the Effluent Disposal Area, Trenches or Irrigation Systems

  • Divert storm water away from the effluent disposal area. If the field is flooded, the soil will not be able to absorb the wastewater coming from the tank. 

  • Only plant grass or shallow-rooted, salt and nutrient tolerant plants in the effluent disposal area. Roots from larger plants may clog and damage the effluent disposal system. 

  • Do not drive cars or allow stock over any part of the system. This can compact the soil and damage the effluent disposal system. 

  • Do not build any structures, including house extensions, pools or sheds, over your tank or effluent disposal area as this will prevent adequate access, evaporation and transpiration of wastewater, and will interfere with the foundations of the structure. 

  • If there is any sign of water pooling on the surface of the effluent disposal area, seek assistance from a licensed plumbing practitioner or service agent immediately.  


Managing grey water and grease traps

Some systems will include a separate system for grey water collection.  

Grey water is the wastewater that comes from the kitchen, laundry and bathroom. Be aware that grey water may have a high number of bad bugs (e.g. virus) and consequently needs to be disposed of appropriately. This means directed to a septic tank, trench or, alternatively, be treated to a high standard before being used for irrigation or reuse within the house.  

Some systems may include a grease trap attached to the kitchen that is designed to collect oils and fats. To keep all systems operating as well as possible: 

  • Clean the grease trap every six weeks. Carefully remove all solids, ensuring that preventative measures are taken, in particular wearing gloves. Ensure the solids are disposed of in an appropriate manner. 

  • Clean the holding/collection well and pumps frequently. You will need a licensed plumbing practitioner or service agent to complete this task. 


Property owners are legally responsible

Maintaining your onsite wastewater management system makes sense so that you don’t end up living with a smell or creating your own wet land as the result of a failing wastewater system. However, it is important to know that Victorians have an obligation to maintain their system under the Environment Protection Act 2017 which is known as a general environmental duty.

Additional to the general environmental duty under the Act, the introduction of the Environment Protection Regulations 2021 introduced a specific legal requirement for you to maintain your onsite wastewater management system in a manner that prevents it from posing a risk of harm to human health or the environment.   

In the case of a property that is rented, this obligation is placed on the property owner and not the tenant. It also requires property owners to provide tenants (occupiers) with written information regarding the correct operation and maintenance of the system. 


When to notify council

The regulations place an obligation on those in control of land on which an on-site wastewater management system to notify council in the event that the system poses a risk of harm to human health or the environment or is otherwise not in good working order.  

Examples given under the regulations of the issues that council should be notified about, include:

  • The absorption field of the system becomes sodden with wastewater pooling on the surface of the surrounding land.  
  • There is wastewater run-off from the disposal area.
  • There is an odour of effluent emanating from or near the system.
  • The drain or toilet of the system is running slowly. 
  • The grease trap of the system is full or blocked. 
  • There are any other signs that indicate that the system poses a risk of harm to human health or the environment or is otherwise not in good working order. 

Keeping maintenance records

The owner of land on which an onsite wastewater management system is located must keep and hold records of all maintenance activities carries out on the system, for a period of five years after each maintenance activity


Need help or have a question?

If you are a tenant of a rental property reliant on an onsite domestic wastewater management system, be sure to contact your property manager should you have any concerns regarding the system.  

Should you wish to receive further information you can contact council’s Environmental Health Officers to ask any questions that you may have and discuss your system by calling (03) 5358 8700 or emailing health@ngshire.vic.gov.au.