What Causes a Septic Tank to Back Up?

What Causes a Septic Tank to Back Up?

septic tank backup

It’s time to look at a topic that may cause chills to run up and down your spine… and with good reason! What would cause a septic tank to back up?

The answers to that one seemingly simple, innocent question are as many and varied as the people who use the facilities emptying into the septic tanks! Let’s look at a few of them together.

Answer #1 on Septic Systems Backing Up

A septic tank backs up because it’s tired of going forwards.

Haha. Gotcha on that one, right? Ok, so I couldn’t resist one very corny joke.

About Your Septic Tank Backup

One of the first things to determine is whether the backup is actually from the septic tank itself, or whether it may be a clog in the plumbing lines somewhere.

Sometimes customers who experience a backup will call in to have their septic tank pumped, and once our technicians pump the tank, the backup is still just as backed up as ever. The reason is often a clogged plumbing line rather than an actual backed up septic tank. Some common causes for clogged plumbing/drainage lines leading to the septic tank are listed below.

Common Causes of Your Septic Tank Backing Up

Tree Roots

This is one of the most common plagues of drainage lines everywhere, even though we love those lovely lawns shaded by a giant, stately old oak or maple trees, right? They’re so beautiful. While it’s true that the upper part, easily seen and appreciated, is beautiful, these trees have a sinister counterpart underground – the wicked root system which is always in search of water.

Tree roots have an uncanny ability to sense water from far away and will go to great lengths to penetrate whatever stands between them and the precious water they so badly need for survival. If a tree root finds the tiniest of cracks in a drainage pipe, it will send a hair-thin root in through that crack to begin sucking up the water and sending it up to the tree.

Once inside, two things begin to happen simultaneously. The tiny root immediately sends out more threadlike roots inside the pipe which begin growing instantly. These roots grow and multiply inside the pipe, sucking up the nutrient-rich water and sending it back to the tree. At the same time, as these roots grow, the tiny root going through the tiny crack in the pipe also grows. As small as it is, it has tremendous strength. It will eventually burst the pipe completely, causing a rupture in the line, which can bring further complications.

Minor root infestations can be treated by a high-powered water-jetting machine, and/or a mechanical augering cutter tool. Once the roots have been cut out and removed, they should be treated with a root-killing chemical to prevent or delay reinfestation. Major infestations will have to be repaired by digging up the infested pipe, removing and replacing it with a new pipe. Special care needs to be given to the connection points in these repairs, as the slightest crack will result in a repeat of the original problem in time.


Do not ever pour grease down your sink. Period. This is one of the surest ways to bring about a backup of your plumbing lines and your septic tank.

Grease will coagulate once it comes in contact with water. It will then harden into a firm substance inside your pipe, and eventually clog your pipes completely, resulting in overflowing toilets, sinks, and showers. Have I said enough?

Some other things not to put down your drains that may cause a backed up septic tank include:

  • Baby wipes
  • Sanitary napkins
  • Feminine products
  • Condoms
  • Bleach
  • Hair
  • Diapers
  • Dental floss
  • Medications
  • Paints
  • Paper towels

Any or all of these will work together to form the perfect backup recipe. Yes, we have seen all of these terrifying scenarios, along with many more, such as false teeth, sunglasses, and even the overuse of antibacterial soaps.

Improper Plumbing Installations

Sometimes a do-it-yourselfer or a novice plumber may install piping with insufficient fall, or drop, in the piping. This causes the water in a flush to run too slowly, permitting the solids to settle to the bottom of the pipe as the water drains away. By the time the next flush comes along, these solids have dried out and attached to the bottom of the pipe, and buildup begins to occur, finally leading to a clog, and causing a backup.

Effluent Filters on the Outlet of Your System

These are designed to protect your leach field from overload, preventing costly repairs of your septic system. Their function is to keep all solids within the septic tank and allow only water to go out to the leach field.

These filters require regular cleaning and maintenance to ensure their proper functioning. Failure to clean and maintain your effluent filter will eventually cause… yep, you guessed it… backup!

Excessive Rain or Flooding

Especially in situations where groundwater and surface water are not properly diverted and drained away from your septic tank and leach field, heavy rains or prolonged wet or rainy seasons often result in backups in your septic system. The long-term cure for this is to have proper drainage work done to ensure that your septic system is kept protected from stormwater. For all these problems and many more, give us a call at Shankster Bros. to find solutions!

FAQs on Septic Systems Backing Up

What are some other warning signs of my septic system backing up?

Signs of a septic tank backup include:

  • Slow drains
  • Gurgling sounds
  • Sewage odors
  • High nitrate levels

How often should I have my septic tank pumped to prevent septic tank backup?

If you’re wondering why your septic tank is backing up often, regular septic tank pumping is essential to prevent backups and maintain the health of your system. The frequency of pumping depends on factors such as the size of the tank, the number of people in the household, and the usage habits.

Can I use chemical drain cleaners if I suspect a backed up septic tank?

No, your typical household chemical drain cleaners should not be used in your septic system. It can cause harm to the beneficial bacteria in the septic tank and may worsen the problem.

What should I do if sewage is backing up into my home?

If your backed up septic tank is causing leakage into your home, it’s essential to act immediately to minimize damage and health risks. Be sure to stop using the water in the house, avoid flushing toilets or using drains, and contact a professional septic service provider for emergency assistance.

Contact Shankster Bros. for All Your Backed Up Septic Tank Needs

Need assistance? We’re here to help! Get in touch with our team today.