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How Long Does A Septic System Last

A properly maintained septic tank can last between 15 and 40 years. Several factors affect how long the system will last, including how often it is maintained, the type of tank you have, its size and its location.

So, in this blog, we are going to explore the lifespans of the four major types of septic tank systems. We’ll also look at the factors that can shorten the lifespan of your tank and what you can do to mitigate them.

The life expectancy of different types of septic tanks



Steel septic tanks are the most common in Australia because they are easy and cost-effective to install. However, this type of tank also has the shortest lifespan. All steel tanks eventually rust, which can cause them to leak.

Several factors can influence how long a steel septic tank lasts, including the type of ground the tank is installed in and the quality of the steel used. If they're well looked after, most steel tanks should last around 25 years, but it is advisable to have a steel septic tank inspected by a professional plumber after 15 years and then every 3 years to make sure it is not leaking.


Concrete septic tanks are the most durable and can last over 40 years if they are well looked after. However, they are more expensive to install than other septic tank systems, such as steel and AWTS.

The longevity of a concrete tank will depend on the quality of concrete used, the size of the tank, the volume of wastewater generated and the soil’s acidity. To increase the lifespan of a concrete septic tank, it should be regularly pumped and cleaned to reduce sludge buildup.

Leach field

The lifespan of a leach field is difficult to estimate, as there are a variety of factors that can affect their longevity. Such factors include the location of the field, the type of construction, the local topography, the size of the field, the soil type and how well it is maintained.

Maintenance is critical to extending the lifespan of a leach field. Leach drains are easily blocked by fats, oils and grease, so they need to be cleaned regularly with an appropriate leach drain cleaner. However, if they are maintained correctly, a leach field should last several decades.


Aerated Wastewater Treatment System (AWTS)


Aerated Wastewater Treatment Systems (AWTS) have more moving parts than other types of septic tanks. This means they are typically more expensive to maintain than other types of tank.

Care also needs to be taken to ensure the AWTS plant is operating at the most optimal conditions for bacteria to digest the waste. If they're monitored and maintained correctly, an AWTS system can last for 30 years or more.

Other factors that affect longevity

Pumping frequency

The most important factor in extending the life of your septic tank is to ensure it is pumped and cleaned out regularly. The pumping schedule of a tank is dependent on its size, the volume of wastewater generated and the number of people in the household.

When your tank was commissioned, you should have been given a pumping schedule. But as a rough guide, a 6500-litre tank servicing a four-person household should be pumped out once every five years.

Soil conditions

The type of soil where your tank is located can impact the lifespan of your system. Ideally, the tank should be located in soil with a high percolation rate and low acidity. The soil type should always be examined before installing a tank to make sure it is suitable.

Nearby trees and shrubs

The roots of nearby trees and shrubs can invade a septic tank, compromising its integrity. As a rule of thumb, trees should be planted at least 10m from the septic tank soakaway, but the further away they are, the better.

Use of water softeners

Water softeners are often used in homes to reduce calcium and magnesium levels in the water supply. However, too much water softener can significantly reduce the lifespan of your septic tank, so make sure water softeners are adjusted and maintained correctly.

Tank location

The location of the tank itself can also be a major factor that determines its longevity. Installing a tank in wet ground, close to a stream, near a watercourse that is prone to flooding, or in areas with a high water table can all shorten the lifespan of your tank.

Get in touch

Parker Plumbing is an experienced installer of septic tanks in Ipswich and West Brisbane. So, if your septic tank needs attention, give us a call on 1300 489 897 and we’ll send around one of our experts to get you sorted.

Alternatively, if you would like to know how much a new septic tank system will cost to install in your home, complete the contact form at the bottom of the page here and we’ll arrange a site inspection and a FREE quotation.

Areas Served

Ipswich & West Brisbane
West Brisbane