How to Maintain a Healthy Septic System

If you don't mind planning ahead a little, you can save thousands of dollars in maintenance costs to your septic system. Here's how.

Many of these tips help reduce the volume of water going into the septic system, and avoid putting in any chemicals which could interfere with how well the system does its job.

  • Wash your laundry in stages over several days - this will avoid flooding the system with large amounts of water at one time.
  • Use low-phosphorus detergents. Phosphorus is a major pollutant of waterways and causes algal blooms.
  • Repair leaking taps.
  • Avoid blockages in the system by installing a lint filter on the washing machine - a stocking over the outlet hose will do.
  • If you've got a blocked drain, use boiling water or an electric eel to clear the line, rather than pouring down caustic soda.
  • Front end loading washing machines are best for septic households as they use far less water and detergent.
  • Use a sink strainer - this prevents particles of food getting into the septic system and slowing down the process.
  • Don't pour oils and fats down the sink - they solidify and may block the system. Instead, put them into a container such as a milk carton and throw out with the rubbish.
  • Install a low-flow shower head to save water.
  • Consider installing a dual flush toilet.
  • Repair leaking taps.
  • Minimise the use of commercial cleaners and bleaches - these can interfere with the bacterial breakdown in the tank. Instead, try using baking soda, vinegar, or a mild detergent solution.
  • Don't flush anything down the toilet that could clog up the system, such as grease, tampons, condoms, paper towels, plastics, or cat litter. These items will quickly fill up the tank, decreasing its efficiency and making it necessary to pump out more often.
  • Don't leave taps running unnecessarily, for instance when cleaning teeth.
  • Keep water from roof downpipes away from the trenches and absorption field. If the field is flooded, the soil won't be able to cleanse the wastewater coming through from the septic system.
  • Add effluent filters to the tank outlet to extend life of trenches.
  • Only plant grass around the absorption field - roots from larger plants such as trees and shrubs may clog and damage the absorption field - and mow it regularly.
  • Don't drive or park over any part of the absorption area. This can compact soil and crush the system.
  • Grow nutrient-tolerant plants near drain fields and irrigation areas.

How the area around a septic system is managed is just as important as how the system itself is maintained. Planning and planting the right kind of vegetation can help keep the system in tip-top condition.

Play it safe - contact Council's Environment Health Officer before installing an irrigation system or doing landscaping around your trench area.

When choosing what to plant, consider which plants will do best in the local soil type, and which ones can cope best with regular daily doses of nutrient-rich wastewater. These plants must be able to cope with nutrients such as sodium, chloride, nitrogen and phosphorus. Many Australian natives can't cope with high levels of these nutrients. Visit your local nursery for advice.

Generally speaking, the best plants to grow on the disposal area are a mix of summer and winter grasses. If the effluent from the septic system is being used to irrigate landscaped areas, nutrient tolerant shrubs and trees can also be planted.

If you have an aerated system, you may find that plants in the irrigation area develop problems with chloride toxicity, which can harm leaves and stunt growth. For trees, chloride toxicity is more of a problem than sodium toxicity. Check with the local nursery to see what they can recommend in these situations.


Recent studies have shown that greywater can contain pollutants and bacteria which are harmful to health and the environment. If you have a greywater system, keep your greywater as clean as possible by:

  • cleaning the greasetrap every 2-4 weeks
  • cleaning the greywater tank at least twice a year
  • using greywater within two hours of it entering the tank (otherwise it can go bad and smelly)
  • spreading your washing over a few days, to reduce the load on the disposal area
  • using strainers in the sink to prevent food going into the system
  • wiping grease out of pans before washing
  • using hot water to wash dishes to prevent build up of grease in the sink.

Groundwater (usually from bores) has been tapped for decades, but only recently have we started to understand how vulnerable it is to contamination from surface activities. Pesticides can find their way into groundwater, as can contaminated water leaking from septic systems. Therefore it is vital to locate the system a safe distance from wells, bores, creeks, lakes and houses, and to keep it well maintained.

Inadequately functioning systems can leak chemicals such as medicines, pesticides, paints, varnishes and thinners into the local groundwater. Some chemicals, even in small amounts, can be dangerous to the environment and public health.

Even if the system itself is functioning properly, these contaminants can still find their way into the groundwater under certain geological conditions. Fractured bedrock and shallow groundwater tables may also allow bacteria and viruses to be transported very rapidly and could contaminate nearby drinking water supplies.


If you're drinking untreated groundwater or using it for cooking and washing food you could be in danger of getting ill. A report from the Nagambie/Tongala area in Victoria warns there are all sorts of impurities to be aware of in groundwater. Despite the fact that the water looked and tasted clean, the report found it contained heavy metals, and leakage from septic systems.