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Septic tanks have been used for years to collect and treat wastewater from homes and buildings that aren’t connected to main sewer lines. A septic system uses a holding tank buried underground to allow solids to settle out of wastewater and to enable some breakdown of contaminants. The liquid effluent then drains into an absorption field or leach field.

However, as sewer infrastructure expands to serve more communities, homeowners now have the option to convert from a septic tank to a connection to the municipal sewerage system. Connecting to council sewer lines eliminates the need to maintain a personal septic system.

Sewerage systems transport wastewater directly to a treatment plant for processing before being released into the environment. For homeowners with septic tanks, converting to a modern sewerage connection provides several benefits related to convenience, costs, property value, and environmental impact. We will explore the key considerations around changing from an existing septic tank to a new sewerage line hookup.


What is the Cost to Convert a Septic Tank Into a Sewer System?

Many factors influence the cost of converting a septic tank into a sewerage system. These include:

The average cost to convert a septic tank to a sewerage system in Australia ranges from $5,000 to $12,000.

Here are some more details on average costs:

  • For an essential gravity-fed sewerage connection, average costs range from $5,000 to $8,000.
  • If a pump system is required to connect the property to the sewer, this can add $2,000 to $5,000 to the overall cost.
  • For properties located further from the existing sewer main, connection costs may be higher due to more excavation and piping needed. Some estimates suggest $300 – $500 per metre of piping.
  • Removal and backfilling of the old septic tanks and leach drains often add $1,000 to $2,000.
  • Sewerage application fees to the local water authority may range from $100 to $1,000, depending on location.
  • Additional restoration work, such as landscaping, concrete, and fences, may cost $1,000 to $3,000.

It’s essential to note septic tanks and sewer lines have different installation costs. Maintenance is another cost factor, as you’ll likely need to pump your septic tank at least once every five years. You’ll likely need to find a local plumber skilled in converting septic tanks to sewerage systems to understand your home’s septic to sewer system costs.

What is the Difference Between a Sewer Line and a Septic tank?

Septic tanks function to collect all wastewater and allow the solids to settle while the liquid percolates out into the soil. Specifically, septic tanks hold toilet waste, sink water, shower water and laundry water. The wastewater flows from the home to the buried septic tank through pipes. Many septic systems use a drain or leach field to disperse the liquid.


Sewer systems transport wastewater directly to a sewage treatment plant through an underground network of sewer lines. At the treatment plant, the sewage goes through multiple levels of filtering and treatment before the water is deemed clean enough to be released back into the environment.


A key advantage of sewer systems is their ability to handle waste from multiple sources and households. Septic tanks have a much more limited capacity and can only service one home at a time. The main difference lies in how and where the waste is collected, treated, and discharged.

Six Reasons to Convert From Septic to Sewer

For several reasons, a homeowner may want to switch from an old septic system to a modern sewer connection.

  • Reduce water bills – Septic systems can use more water than sewer systems since they rely on large volumes of wastewater to transport solids effectively.
  • Protect the environment – Septic tanks can release methane and other greenhouse gases as waste decomposes. Connecting to municipal sewage treatment reduces these impacts.
  • Save space and maintenance costs – Septic tanks occupy space on your property for the tank and drain field. They also need regular pumping every 3-5 years to remove sludge build-up. Sewer connections avoid these hassles and expenses.
  • Increase home value – Most home buyers prefer a property connected to the public sewer system rather than dealing with an aging septic tank. Upgrading can increase resale value.
  • Improved safety – Septic systems are prone to backups and overflows during heavy rains when water tables are high and soil absorption gets overwhelmed. Sewer connections eliminate this risk.
  • Avoid other septic issues – Old septic tanks are prone to clogs and blockages over time as pipes get fouled by roots or solids. Switching to a sewer line avoids the need to troubleshoot septic problems continually.

The Conversion Process

Converting from a septic system to a sewer connection involves several key steps:

  • Get quotes from qualified plumbers or contractors with experience with septic to sewer conversions. They can assess your specific situation and provide accurate estimates.
  • Ensure your property can physically connect to the nearest sewer line. This may require a gravity-fed pipe downhill or installing a grinder pump if uphill.
  • File permits with your local council for the construction work and required inspections.
  • The old septic tank must be emptied and filled with dirt or gravel. Any piping linked to the septic tank and leach field will be removed or closed off.
  • Installation of new pipes to connect the home’s plumbing directly to the municipal sewer line. This includes digging trenches for the new sewer line, laying piping, adding cleanouts, backfilling over the pipes, and linking to the existing plumbing.
  • Once connected, restore any landscaping, concrete, fences or structures impacted by the new sewer line excavation and work.
  • Schedule an inspection by the local authorities when work is complete to ensure proper installation and function.
  • Pay any outstanding sewer connection or application fees to the water/wastewater utility provider.

The whole conversion process typically takes 2-3 days of intensive work. Homeowners will want to find an experienced contractor they can trust to ensure the transition from a septic system to a sewer is as smooth as possible.


Ongoing Use and Maintenance

Once converted to a sewer system, there is little ongoing maintenance required by homeowners. You no longer have to schedule and pay for septic tank pumping. Instead, regular sewer fees will be included in your water utility bill. The local authorities may require periodic inspections of the connection point. However, the municipal providers generally handle the sewer lines and wastewater treatment. Contact a professional plumber immediately if problems arise in your home’s pipes. Otherwise, the sewer system essentially runs trouble-free without much homeowner maintenance needed.


Converting from septic to sewer involves considerable costs but provides significant ongoing benefits. While the process takes coordination, working with qualified local plumbers like the Gold Coast Plumbing Experts team ensures your sewer conversion goes smoothly. For any plumbing inquiries or fixes, contact Gold Coast Plumbing Experts today.