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How Much Does a Septic Tank Cost?

$7,000 - $15,000

    How Much Does a Septic Tank Cost?

    The septic tank price in Australia can vary depending on the size of the home and the location. The average septic tank cost for a conventional system with absorption trenches for a four-bedroom home is between $11,000 and $13,000, with desludging every three to five years.

    City Average Installation Cost
    Sydney $8,000 – $15,000
    Melbourne $8,000 – $15,000
    Brisbane $7,000 – $15,000
    Adelaide $10,000 – $15,000

    Factors Impacting the Cost of a Septic Tank

    The job you want done: A septic tank systems cost can vary considerably, depending on whether you’re installing a new septic system or replacing an old tank.

    Size of the tank: The size of the tank has a considerable impact on the septic tank system cost. Septic tanks take in the wastewater from bathrooms, dishwashers, and washing machines. All the water from your home drains into one container. The tank must be adequate for your needs.

    Type of tank: Many factors will affect the kind of tank you choose. They include home size, soil type, lot size, proximity to sensitive bodies of water, and local regulations. Some of the standard septic tanks are conventional systems, recirculating sand filter system, aerobic treatment unit, and drip distribution system.

    Tank material: The material the tank is constructed of has an impact on the cost. A septic tank that’s made of concrete is inexpensive to install but must be replaced more often than a more expensive system. A polyethylene tank that’s high-density initially costs more to install but lasts longer.Location: The location can affect the cost of septic tank systems. Above-ground systems can cost less to install, but the maintenance is more expensive than underground systems.

    Price Estimates for Different Types of Septic Tanks

    Conventional Septic Tank $2,000 to $5,000

    The cost includes the tank. Prices may run between $4,000 to $12,000 in areas where the cost of materials and labour is higher.

    Aerobic/Aerated Wastewater Treatment System$10,000 to $20,000

    The aerobic septic system cost is for alternative systems that use aerobic and sand/peat filters.

    Septic Tank With Sand Filter$5,000 to $9,000

    A mound system may run between $8,000 and $20,000, depending on the grade and the slope of the property.

    Price Estimates for Different Septic Tank Materials

    Material Average Cost
    Concrete $1,200 to $5,000 is the concrete septic tank price for a tank that ranges in size from 3,000 litres – 12,000 litres
    Steel $3,000 to $10,000 is the average cost. Most homeowners spend between $3,500 to $5,000
    Plastic $500 to $1,500 for a tank that ranges in size from 3,000 to 5,000 litres
    Fibreglass $1,500 to $2,000 for the average home with three to four bedrooms
    Poly Poly septic tank prices range from $500 to $1,500 for an average size tank between 3,000 – 5,000 litres.
    Black septic tank being constructed in the ground of a backyard home.

    Septic tank construction. | Source: GURNETT GROUP PTY LTD

    Septic Tank Pump Out Cost

    How much does it cost to pump out a septic tank? 

    The average cost is $300, but can run up to $500, depending on your location. The tank should be pumped out every three to five years.

    Septic Tank Cleaning Prices

    How much does it cost to clean a septic tank? 

    The average cost is between $250 and $600. Most homeowners spend approximately $375. The cost of pumping out the tank could be about $250 for a 3,000-litre tank and up to $1,000 for a 5,000-litre tank.

    How to Hire Septic Tank Installer

    • Get the necessary permits
    • Have the field surveyed
    • Prepare and excavate the site
    • Have the plumbing stubbed out
    • Install the tank
    • Have the plumbing connected

    How to Create an Accurate Estimate

    • The cost of the septic tank installation depends on:
    • Size of the home
    • How much water you use
    • Cost of permits
    • Soil tests
    • Excavation equipment

    Licencing and Qualifications

    When you’re having a septic system installed, always make sure the contractor is licenced and has the necessary qualifications. The installer should handle all the required paperwork, council permit applications, council inspections, and the installation of the septic tank.

    How to Save Money Hiring a Septic Tank Installer

    • Clear the land and have it ready for the tank installation
    • Buy the gravel
    • Get the necessary permits



    * The cost data is based on Oneflare and third-party sources

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