A septic system can operate effectively for many years, but no system lasts forever. Aging tanks, recurring blockages, poor drainage and changing property requirements can all be signs that it is time to investigate replacement options.
Installing another septic tank may seem like the obvious solution, but it is not the only one. Where suitable sewer infrastructure is available or being introduced, connecting the property to a sewer network can provide an alternative to continuing with onsite wastewater treatment.
For some properties and communities, a pressure sewer system can make this transition possible, particularly where extending a conventional gravity sewer would be difficult or costly.
Septic systems rely on the tank, associated pipework and disposal area working together effectively. As these components age, problems can develop with the treatment, storage or disposal of wastewater.
Some common signs that a septic system may need replaced include:
These symptoms do not always mean the entire system needs replacing. Some can result from isolated plumbing or maintenance issues, so the condition of the system should be properly assessed before deciding on the next step.
When a septic system is no longer containing, treating or disposing of wastewater effectively, it can create more than an inconvenience. Poorly functioning systems can result in odours, wastewater overflows and potential impacts on surrounding soil and groundwater.
The system may also become unsuitable as the property changes. For example, infrastructure designed for a smaller dwelling or lower wastewater load may no longer be appropriate following renovations, additional development or increased occupancy.
At this point, repeatedly repairing an aging system may not address the underlying problem. Property owners may need to consider whether to replace the onsite system or move to a different method of wastewater servicing.
The right solution will depend on the property, available infrastructure, ground conditions and local council or utility requirements. There are generally three pathways to consider.
Where the problem is confined to a particular component and the rest of the system remains suitable, repairs may extend its operating life.
This can be practical for relatively minor faults. However, ongoing repairs may become less economical when the tank, pipework or disposal area is approaching the end of its useful life.
A like-for-like or upgraded septic tank replacement may be appropriate where onsite wastewater treatment remains the preferred or only practical option.
The new system still needs sufficient space and suitable site conditions for wastewater treatment and disposal. Depending on the system and local requirements, ongoing pumping, servicing and maintenance may also be required.
Where sewer infrastructure is accessible, moving away from onsite treatment altogether may be another option.
Instead of wastewater being treated and disposed of within the property, it is transferred into a sewer network and ultimately treated at a centralised wastewater treatment facility, shifting responsibility for treatment to the local water authority rather than the property owner. Where that facility is also a water recycling plant, this can support capturing more wastewater for recycling rather than individual onsite disposal.
A conventional gravity sewer connection may be possible in some locations. In others, particularly where gravity drainage is difficult or expensive, a pressure sewer system can provide an alternative method of achieving the connection.
The exact process varies depending on the property and the sewer infrastructure available. Generally, the existing septic system is decommissioned in accordance with local requirements and a new connection is established to the sewer network.
This connection may use a conventional gravity sewer or, where gravity drainage is impractical, a pressure sewer system. Understanding the differences between gravity sewer and pressure sewer can help determine which approach is most suitable for the location.
With a pressure sewer connection, wastewater from the property flows into a collection unit containing a pump. When the wastewater reaches a predetermined level, the pump transfers it through a small-diameter pressure main and into the wider sewer network.
Because wastewater is pumped rather than relying entirely on gravity, pressure sewer networks can provide greater flexibility around natural terrain, ground conditions and existing development.
For a property owner dealing with a failing septic tank, pressure sewer may not initially be an obvious replacement option. However, where connection to a pressure sewer network is available, it can offer several advantages over installing another individual onsite treatment system.
With a septic system, wastewater treatment and disposal occur onsite. Connecting to sewer transfers wastewater away from the property for treatment through the broader wastewater network.
This removes the need to install another individual septic treatment and disposal system on the property.
Onsite wastewater systems can depend heavily on soil characteristics, groundwater levels and the availability of adequate land for effluent disposal.
Pressure sewer networks use pumps to move wastewater through sealed pipework, making them particularly useful where conventional wastewater servicing is constrained by difficult terrain or site conditions.
Gravity sewers generally rely on pipes maintaining the required fall towards downstream infrastructure. This can require deeper excavation or additional pumping infrastructure where the natural topography does not support gravity flow.
Pressure sewer systems actively pump wastewater through the network, allowing small-diameter pressure mains to follow the terrain more closely. This can make sewer conversions practical in locations where extending conventional gravity sewer infrastructure would be difficult.
Pressure sewer does not have to be limited to an individual property. It can be used as part of a coordinated conversion program for multiple homes or an entire community.
Where an area contains a large number of aging or unsuitable septic systems, pressure sewer infrastructure can provide a way to progressively connect properties to a common wastewater network.
Not necessarily. A pressure sewer system needs somewhere suitable to discharge the wastewater, so its viability depends on access to existing or planned sewer infrastructure as well as the requirements of the relevant water authority.
For isolated properties without access to a sewer network, an upgraded onsite wastewater treatment system may remain the more appropriate option.
Where a sewer connection is possible can also depend on factors such as:
Looking at these factors early can help determine whether another onsite system or conversion to sewer represents the more appropriate long-term solution. Read our designated article to learn more about how a pressure sewer system works.
If your septic system is aging or beginning to fail, start by understanding the condition of the existing infrastructure and the servicing options available to the property.
Replacing the septic system may make sense where onsite treatment remains practical and there is no accessible sewer network. Where a connection is available, however, moving from septic to sewer may provide an opportunity to transition away from onsite wastewater treatment altogether.
Pressure sewer can make that connection possible in locations where extending a traditional gravity network is constrained by terrain, ground conditions or existing development.
Considering these alternatives before simply replacing an old tank can help property owners, councils and developers identify the wastewater solution best suited to the site and its longer-term requirements.
Global Water provides pressure sewer solutions for projects across Australia and New Zealand, including applications where properties and communities are transitioning away from existing septic systems.
If you are investigating options for replacing aging septic infrastructure, contact Global Water to discuss your site requirements and whether a pressure sewer solution could be suitable for your project.