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Septic system failure signs (and what to do about them!)

Septic contractor replacing a failed Bionest-type septic system with the Ecoflo compact biofilter.

If you own a septic system, you need to know the signs of a failing installation, what causes them, and what your next steps should be.

This knowledge is a great way to maximize the lifespan of your system. Better yet, it will help you protect your health and the environment, prevent damage to your property, and save you big money on repairs.

What is a septic system failure?

A septic system failure happens when untreated wastewater goes where it shouldn’t.

Often, a failure forces sewage back into your home, or pools it above your septic tank or drain field (also known as a leach field). Less obvious failures allow sewage to seep through your soil and contaminate groundwater or watercourses.

Telltale signs of septic system failure

The clearest and perhaps the most dreaded sign of septic system failure is a sewage backup.

It happens when your system is clogged or full. Because sewage cannot flow through your septic tank and into your dispersal area, it must go somewhere else instead. Unfortunately, “somewhere else” is the surface of your yard or back into your home.

There are plenty of other red flags for failing septic systems. They do not necessarily mean that your installation is doomed, but they require quick action to prevent more serious consequences.

Contaminated well water

Improperly treated wastewater can infiltrate into your soil and end up in water sources, including the wells serving you and your neighbours. If your drinking water tests show abnormal levels of coliform bacteria or nitrates, the source of the contamination is likely a failing septic system.

Algae blooms in nearby lakes and rivers

Child standing in lake water polluted with blue-green algae, also known as cyanobacteria.

Algae is a normal part of some lakes and rivers. But watch out for sudden and excessive algae blooms in watercourses near your property. They may be caused by nitrogen or phosphorus contamination from a failing septic system.

Slow-moving drains

Beware of slow drains! They are often a warning before your septic system backs up into your home.

The source of the problem may be food scraps (especially from a garbage disposal), fats, oils, greases, or non-flushable items in your pipes or septic tank. These materials clog your system, preventing your toilets, sinks, and other fixtures from properly draining.

Gurgling or bubbling sounds

It is normal to hear sounds when your toilet flushes and refills. The same goes for sinks, tubs, and washing machines. But if you notice a strange gurgling or bubbling sound, it is a strong indication that you have blocked pipes or a full septic tank.

Bright green or spongy grass

Green grass is a good thing, right? Not always. If you notice isolated patches of extra bright or spongy grass near your septic system, it may be leaking wastewater contaminated with nitrates or other nutrients.

Standing water

Water from a leaking septic system pooling over a septic tank lid.

If foul-smelling surface water appears and remains near your septic tank or drain field, your system might be leaking improperly treated wastewater onto your property.

Bad odours

Bacteria inside your septic tank produce gas when they break down waste. Normally, the resulting odours are no problem thanks to vents in your rooftop and septic system.

If the area inside your home or around your installation starts smelling nasty — it can be a bit like rotten eggs — then there is probably a blockage or malfunction in your system’s ventilation.

What is the most common cause of septic system failure?

For our money, the most common cause of septic system failure is inadequate maintenance.

Regular maintenance from qualified professionals is the best way to spot and correct small problems before they lead to more expensive damage. Skip the service, and you set yourself up for big headaches in the future.

Of course, lack of maintenance is not the only cause of septic system failures. Other culprits can be just as damaging to the long-term health of your installation.

Poor design or installation

Proper septic system design and installation are crucial for effective wastewater treatment. Your system is more likely to fail if it is:

Overloading the system

Woman loading laundry into a washing machine connected to an on-site septic system.

Your septic system is designed to receive a specific amount of wastewater. If you exceed this amount, you risk overloading your system and harming its performance. Most often, the excess comes from:

  • additional household occupants
  • consecutive baths or showers
  • excessive washing machine or dishwasher use
  • gutters, sump pumps, or air conditioners connected to your system
  • water softener backwash discharging into your system
  • pool or spa water draining into your system

Clogged septic pipes or effluent filter

Septic pipes and effluent filters clog due to inadequate maintenance or improper system care.

You should have your septic tank pumped every three to five years, or according to the regulations in your area. You or your septic technician should clean your effluent filter every time your tank is emptied.

Also be mindful of what you put down your drains. Septic-safe toilet paper and wastewater from laundry, sinks, and bathrooms are just fine. Avoid wet wipes, food scraps, fats, oils, and greases because they may lead to blockages or the need for more frequent septic tank pumping.

Physical damage

Cracked septic drain field pipe filled with roots from a nearby shrub or tree.

When structures, vehicles, boulders, retaining walls, or other heavy objects are too close to your septic system, they can cause significant damage to its components. Even roots from nearby trees can block or burst septic pipes.

Save yourself the cost of preventable repairs by respecting the clearance zones recommended by your system’s manufacturer.

Biomat buildup

Biomat is a black sludge that gradually forms in the soil around or just below your septic drain field. It is mostly made up of anaerobic microorganisms (those that do not need oxygen to survive).

A certain amount of biomat is normal as your system ages. But if your septic tank is too full, your effluent filter is clogged, or you put products that are not septic safe down your drains, you risk a biomat that grows too fast and clogs your drain field. The result is backups or standing water.

How to fix a failed septic system

Premier Tech Water and Environment technician inspecting a homeowner's septic system in Québec, Canada.

When you suspect your septic system is failing, the obvious question is how to fix it.

The answer can be simple or complex depending on your unique situation. Our best advice is to seek help to identify the problem and avoid doing anything to make things worse. That means never climbing into your septic tank or digging up components on your own.

These steps will get you started:

  1. Damage control
    Untreated wastewater is hazardous because it carries pathogens. If you find it pooling in your yard or backing up into your home, clear the area to keep people and pets away. Do not attempt to clean the mess yourself unless you have proper protective gear, and you are certain there is no risk to your personal safety.
  2. Call a septic professional
    Get on the phone and call your septic professional as soon as possible. For emergencies and non-emergencies alike, your local pro has the experience, equipment, and expertise to correct the problem.
  3. Contact your system’s manufacturer
    The best septic system manufacturers back their products with after-sales support and services. At Premier Tech Water and Environment, we maintain and repair Ecoflo septic systems. We also have the expertise to service all other technologies, including Bionest-type installations.
  4. Talk to local authorities
    As a responsible homeowner, you need to discuss your failing septic system with your municipality or environmental authority. These local contacts will be able to assess the problem and advise you on specific steps to take.
  5. Connect with your insurance company
    If wastewater backs up into your home, reach out to your insurance company for details about coverage and compensation. Your policy may have a rider for sewage backups. Even if it doesn’t, you are likely protected for general water damage.
Installation of the Pack model of the polyethylene Ecoflo compact biofilter at a residential site in Ontario.

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Our septic service technicians can help you extend the life of your current system.

But if the time has come for a replacement, get step-by-step support by contacting our team today.

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Last update: 2023.09.28

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