Septic tanks and on site waste water treatment systems need regular maintenance to work properly. You also minimize the impact on the environment if your system is well-maintained.

Owners are legally responsible for maintaining their on-site wastewater treatment system.

There are health risks for you, your family and your community from poorly maintained waste water treatment systems. Poor maintenance of treatment systems can cause sewage effluent to rise to the surface or effluent to enter the ground water system. People and animals can fall sick by coming into contact with raw sewage of by drinking contaminated groundwater.

The life of your system depends on how much effluent is discharged each day and other factors like rainfall and general clogging of pores in the ground. But the greater impact is how you maintain your system and what put down it.

Components of Your System

Your onsite waste water system is comprises of two main parts:

  • Waste water treatment unit – generally a septic tank or aerated treatment system.
  • A land application system – generally trenches, or low pressure surface or subsurface irrigation drip lines.

Both parts of the system need to be maintained to ensure that no health effects occur.


  • Use biodegradable household cleaners and synthetic laundry powders of liquid (ie. Petroleum based)
  • Use body washes and shower gels, instead of soap, as former are petroleum based.
  • Use the water and suds saver cycles on your dishwasher and washing machine (if fitted) and put a water saver device on your shower.
  • Fix any leaking pipes and toilet systems.
  • Clean septic tank outlets and filter when required (Usually every 6 months)
  • Follow the service and maintenance requirements of your system.
  • Scrape all dishes to remove food material, etc before washing.
  • Keep all possible solids out of the system.
  • Inspect tank annually for sludge and scum levels.
  • The tank should be pumped out approximately every 3–5 years. Have tank pumped out when
  • The top of the floating scum is 75 mm or less from the bottom of the outlet
  • Sludge has built up to within 250 mm of the bottom of the outlet


  • Use soap-based washing powders
  • Install a waste master disposal in your sink
  • Dispose of egg shells, coffee grounds of tea bags as they are biodegradable. Dispose of these in the rubbish and compost food scraps or put in rubbish.
  • Dispose of strong bleaches, chlorine compounds, antiseptics or disinfectants, medicines or disposable nappies, sanitary napkins/pads or condoms into drains.
  • Allow fat to be poured down the sink.
  • Put petrol, oil, flammable/explosive substances, trade waste or chemicals down the drain.
  • Empty a spa or swimming pool into the system.

Signs of Trouble

The system is not working correctly if:

  • there is a foul smell around tank or land application area
  • the tank, gully trap or tank mushroom is overflowing.
  • the ground around the tank is soggy
  • sinks/basins/toilets are emptying slowly or making gurgling noises when emptying
  • the grass is unusually dark green over the land application area

Surface Water Cut-off Drains

If your disposal system is located on a slope, a surface water cut-off drain will usually be installed above the effluent disposal system to prevent stormwater runoff from the slope entering the disposal area. All surface water cut-off drains need to be maintained to make sure they work properly. This may include removing excess grass or plant growth from the drains and making sure there are no other obstructions to prevent the free flow of water.

Prior to winter, it is a good idea to give all surface water cut-off drains a quick visual check and to carry out any required maintenance as soon as possible. If a surface water cut-off drain is not working properly, the excess stormwater entering the disposal area will cause failure of the disposal system and result in effluent flowing down the slope.

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