Request Service Today

Can a septic system back up into the house?

If the septic tank has a leak or it gets clogged, it can flood the leach field and sewage can back up into your sink, shower or household drains. Before we delve into the reasons behind the backup, the first step is to understand how a septic system works.

Septic systems have three components:

  • Pipes:The pipes from wastewater outlets like toilets, sinks and tubs carry the wastewater to the septic tank.
  • Septic Tanks: The septic tanks use biological processes to break down the solid particles. Septic tanks can be made of concrete, fibreglass and polycarbonate plastic.
  • Absorption Trench: The processed effluent is distributed in the absorption trench where it is absorbed by the soil under the surface.

Any blockage in either of the components can lead to overflowing wastewater in your house.

Septic Systems

Types of Septic Systems

Gravity Septic Systems

These systems carry wastewater downslope into the leach field. If not managed and designed correctly an issue with this style of septic system can be that the soils can become oversaturated as the effluent can remain limited to a small area.

Pressurised Septic Systems

If the leach field is situated upslope from the septic tank a pressurised system is needed to distribute the effluent. These systems use pumps to distribute the effluent throughout the leach field reducing the chances of a backed-up septic tank. However, these systems need regular maintenance as clogs in pipes can lead to a malfunctioning septic tank and the entire pipe network may have to be replaced if it gets damaged beyond repair.

Is sewage water backing up in your home? Let our septic system experts help you.

Reasons behind septic tank backup

Incorrect installation

The installation of the septic tank is not carried out as per the plumbing code by an experienced wastewater company.

Clogs or blockages

When was the last time you got your septic tank checked by a professional? Septic tanks need to be pumped out every 3-5 years as they accumulate solid waste over time. If you have gotten it checked recently or the water is backing up in just one outlet, the clog could be in your plumbing. However, if multiple sinks or drains are clogged, the problem could be due to blockage in the septic tank such as the effluent or baffle filter or tank inlet could be clogged.

The frequency of septic tank pumping out depends on various factors like:

  • The number of people in your house
  • How often do you use your dishwasher or washing machine?
  • How long do you take showers for?
  • If you have high water demand, consider getting the septic tank checked more frequently

Tree roots

Tree roots can wrap around pipes to and from the septic tank and cut off the water flow allowing an accumulation of debris. Avoid planting trees or large shrubs in the vicinity of the septic system grass or small plants are recommended.

Heavy machinery or vehicles moving over the septic system

Vehicles or machinery moving over the septic system or absorption area can damage the pipes and tank. Demarcate the location of your septic system and trenches and keep the map of septic tanks and pipes handy to avoid crushing your septic system.

Harsh chemicals and antibacterial soaps

The naturally occuring bacteria in the septic tank plays a major role in breaking down the solid waste. If you are using too many chemicals or antibacterial soaps around your home it can disrupt the delicate bacterial composition present in the tank and can cause the waste to accumulate as it won’t be broken down effectively.

Water overloading

Too much water in the septic tank or heavy rains can also overload the system and cause wastewater to backup. Also, check the pipes for any leaks and get them repaired promptly. Consider installing water-efficient showerheads and taps to conserve water and limit the flow through the wastewater system.

Disposing of solid materials down the toilet or drain

Avoid flushing feminine hygiene products, flushable wet wipes, condoms, coffee grounds, paper towels, solid food waste, diapers down the drain as these can block the pipes and disrupt the bacterial balance in the tank.

Can a septic system back up into the house? Let our experts help you.

Not what you're looking for?

Try our search below for more information relating to septic, sewage and wastewater systems.

Search Help Section by Service

Search our information section by a specific service. Simply click the tile below.

Septic Tanks

Sewage Systems

Wastewater Treatment

Why Use Express Wastewater Solutions?


    Because we are not a manufacturer and not tied to one particular system we can always offer the best solution for your wastewater needs.


    Because we do this every day we have developed a close knit expert team for every step of the process – from plans and council paperwork to excavations, electrical and plumbing. We handle it all to make the whole process as stress free and quick as possible.


    Most people have never installed a home sewerage treatment plant and don’t know the next step, that is why we offer a free 30 minute phone consult with one of our experts to point you in the right direction.


    We handle your wastewater installation from start to finish we can deal with all the trades, council everything so you don’t have to worry about a thing.


    Have peace of mind knowing that Express are licensed, insured professionals that will do your job right the first time.


    Not sure what system is right for you, or want to know if your system is working properly? Just give one of our friendly wastewater experts a call and they will be more than happy to help.


    We will always look to repair your system rather than replace it if it does not need to be, which will generally save large amounts of money sometimes up to and over $10,000.