- Site Analysis
- Site Use
- Passive Design
- Water supply
- Building design considerations
- Sanitary plumbing systems
- Drainage systems
- On-site wastewater treatment
- Stormwater control and landscaping
- Water supply
- Material Use
- Wet Areas
- Health and Safety
- Other Resources
Water use, sustainability, and efficiency by choosing quality systems and materials, and providing environmentally friendly solutions.
Maintenance and problems
Owners are legally responsible for maintaining their on-site wastewater treatment system.
On this page:
- Maintaining septic tank systems
- Maintaining aerated water/advanced sewage treatment system
- Maintaining land-application/disposal systems
- Avoiding problems
- Signs of trouble
- Solving problems
Maintaining septic tank systems
- 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
- Check and clean outlet filters regularly (6-monthly)
- Alternate dispersal to the land-application areas approximately every 3–6 months.
Maintaining aerated water/advanced sewage treatment system
AWTS and ASTS should be serviced by a qualified service person, generally every 6 months, to:
- clean or replace filters as required
- monitor the effluent quality, including pH level, of the first chamber
- check the submersible pump and float switch operation
- record all inspection maintenance and monitoring events
- replace the submersible pump at 7–10 yearly intervals.
Maintaining land-application/disposal systems
- Keep the area clear of deep rooting trees and shrubs (these may grow into and cause blockage of the system).
- Clean and service pumps, siphons and filters according to manufacturers’ instructions.
- Flush drip lines regularly to remove accumulated sediment.
- Redirect effluent periodically to alternative trenches or beds (septic tanks).
- Mow grass and maintain plants in evapo-transpiration areas.
- Ensure that surface water drains around land-application areas are kept clear to reduce rainwater runoff into trenches or beds.
- Specify water-efficient appliances.
- Prevent overloading the system by minimising water use (e.g. spread heavy water-use activities such as clothes washing over several days) and installing a separate greywater treatment system.
- Strong chemicals restrict the biological action within the tank – select cleaners and washing products that do not hamper the decomposition process, and make sure chemical products such as volatile thinners, bleaches and disinfectants do not enter the system
- Kitchen waste should not enter on-site wastewater treatment systems – compost kitchen waste instead of installing a garbage disposal unit.
- Systems cannot deal with condoms, dental floss, tampons, sanitary napkins, nappies and nappy wipes – these should be wrapped up and disposed of in the rubbish.
Signs of trouble
The system is not working correctly if:
- there is a foul smell around tank or land application area
- the tank overflows
- the ground around the tank is soggy
- sinks/basins/toilets are emptying slowly
- fixtures make a gurgling noise when emptying
- the grass is unusually dark green over the land application area
- black liquid is oozing from the trenches
- a gully trap or tank mushroom is overflowing.
Tank is too full
Have it pumped out
Tank contains too much sludge and scum
Have it pumped out/desludged
Too much water going into the tank
Use less water and check for stormwater infiltration
Toxic chemicals are going into the system
Reduce use of hard detergents/cleaners