6 Ways To Fix Backed Up Septic Tank System (Do This!)


If your septic tank is backed up, it often means you’ll have to call a professional to fix the issue. That’s important because your local building or health authority may require that you have a permit to fix a septic system.

Here, laws vary from state to state and city to city. Therefore, it’s important that you check the requirements and apply for any necessary permits before doing the work. 

In addition, soil testing, percolation testing, and bacteria testing require equipment. Professional plumbers will also have the equipment to snake or tunnel out clogged pipes, excavate your tank or drain field, etc.

Therefore, doing the job yourself might not be the cheapest or best idea. However, if you have the tools, you can do some of the work yourself. 

Symptoms Of Backed Up Septic Tanks 

If your septic tank is backed up, you’ll quickly notice signs. 

  • Issue Affects All Drains – If all of your drains are having issues, it’s very likely to be a septic tank issue. Therefore, if one drain floods, overflows, or drains very slowly, you can normally check if it’s a local pipe issue or the tank by checking the rest of the drains. Of course, you don’t want to leave the water running too long; if it is a tank issue, it will only make the issue worse. 
  • Water Level Is Too High – Most septic tanks allow you to check the water level in the tank. If you have an access port, open it and check if the water is above the high mark. If so, the septic tank is backed up. 
  • Bad Smells – If you smell sewer around your drains, in your lawn, or around any taps, it’s a good sign the septic tank is backed up. 
  • Wet Lawns – Wet patches on your lawn are always a sign that your septic tank is leaking. If you don’t notice wet or water pooling, you might notice extra plant growth or particularly green grass in that area. 
  • Trees or Plants Over the Septic Tank and Drainfield – Trees and large plants around a septic tank will almost always cause problems. If they are there, the roots will grow toward the source of water and nutrients. 

1. Clogs In Your Septic System 

Photo: Minnesota Pollution Control Agency / Flickr / CC BY NC 2.0

Clogs are the most common cause of a backed up septic tank. Here, some material has blocked the drain pipe or one of the flow pipes (dip or H) between the home and the tank. 

=> Looking for a custom house floor plan? Click here to fill out our form, a member of our team will be in touch.

Here, it’s important to note that if there’s a block at one toilet, the full system won’t be affected. Instead, you’ll be able to use all your other drains normally.

See also  P-Trap Vs. S-Trap: 10 Key Differences [Explained]

So, if your bathtub and toilet are backing up but the kitchen sink on the same system runs normally, the issue is in the bathroom drain pipe, not the septic tank. 

On the other hand, if every drain in your home is affected, the issue is likely in the tank itself. That may be the waste pipe leading to the sewer.

It might also be the pipes between tanks in your septic tank. And, it might be the leech or drain field. 

A clog at any of these points will mean that water can no longer flow into the system. When it does, it will eventually overflow, causing a backup.

If there’s also air pressure, your sewer could actually push a significant amount of sewage back into your home. 

Here, the main culprits are: 

  • Foreign objects such as plastic bags, menstrual pads, tampons, diapers, cleaning cloths, etc. 
  • Hair, string, or other household debris
  • Food waste, especially if fatty, which clumps together and causes a blockage 

However, clogs can also come from issues inside your septic system itself – for example, if the ecosystem of bacteria has died off because of excessive chemical usage.

In this case, you might have a buildup of sediment because solids are not breaking down. This can cause it to rise to the level of the H or drip pipes, preventing wastewater from flowing through. In this case, you’ll have to empty the septic tank or replace it – or use a temporary tank while a new bacteria infusion resolves the issue. 

How To Fix 

In most cases, fixing a clog in your septic system involves inspecting the tank and the system. Most professional plumbers will start by using a plumbing snake or mechanical snake on the system, from the source of a toilet.

If that doesn’t resolve the issue, you may open the septic tank and check solid levels, check the drain field, and otherwise assess where the clog might be. 

In some cases, you can fix the issue using a chemical declogger. However, this is extremely unlikely.

If a chemical declogger or a baking soda solution works, the problem is most likely in the main waste pipe leading to the septic tank and not in the tank. 

2. Tree Roots 

Tree roots and large plant roots can clog your septic tank at any point. In addition, they can break the outer shell of the tank and through the seams where pipes attach.

Here, the most vulnerable part of your septic system is the leech or drain field. If tree roots grow into the open holes, they can clog. 

When that happens, your septic system will have reduced water flow. You probably won’t notice the issue at first. But, as more roots grow, the problem will get worse. Eventually, the system will back up. 

How To Fix 

In most cases, the easiest way to get roots out of your drain field is to use an auger. Take off the caps or find the open end of the pipe.

Then, insert the auger and drill out the roots. After that, you can flush the pipes to remove the debris. 

Once roots are out, you can re-burry the pipes and your system will operate as normal. 

See also  How to Lay Underground Drainage Pipes: A Step-by-Step Guide

If that doesn’t work, the only way to fix roots growing into a leach field is normally to replace the leech field. That means getting a repair permit, digging up the piping, and replacing it. When you do, it’s important to install root barriers at the same time. 

Here, you dig and install barriers using hard plastic sheeting. Many areas also require that you map a plan of least resistance for your tree roots to follow instead.

You can then use soil and root barriers to direct roots to nutrient and water-rich spots they might want to grow towards anyway. 

3. Sewage Leaks 

If there are cracks, burst pipes, or other damage to your septic tank or the system around it, you could get backup into the house. Here, common causes include the septic tank shifting.

If hydrostatic pressure forces the tank upwards, it could put too much stress on part of the system. Therefore, either the system or the pipes could crack.

If someone drives a car or a heavier vehicle over the area, it might also crack. That can mean the tank, the leach field, or the waste pipe could crack. 

Even extreme cold could cause similar problems. And, over time, age could cause the materials to degrade, resulting in a crack or a break. 

How To Fix 

First, it’s important to figure out where the leak is coming from. Wet spots, bright green spots in the lawn, and more plants or grass growing in one area are very big tells.

Once you do, you’ll have to dig up the area to see what’s going on. 

If the tank itself is cracked, you’ll have to replace it. However, if you have an issue with old or damaged seals, you can simply replace those instead.

In addition, if it’s just a pipe, you can replace that section of the pipe. However, if one part of the tank has issues, it’s more likely that other parts of it will as well.

Therefore, it’s always important to inspect the full system and do a pressure check. 

4. Major Increase Of Water Usage 

Photo: Bill Wilson / Flickr / CC BY 2.0

If you suddenly have a large increase in water usage, it could overwhelm your system.

Examples include if you connect heavy machinery like a professional pressure cleaner, suddenly have 8 family members staying over, or try to drain a swimming pool into your sewer. 

These increases in water usage are not something you can achieve by having 1 or 2 guests over. However, when they do happen, they can cause your sewer to overflow, either into your yard or into your bathroom. 

How To Fix 

If you’ve suddenly increased the amount of water you’re using, the solution is to either stop or replace the drain field.

Here, your drain field is probably designed to release water at a similar rate to how you use it. That’s because the more slowly you release water into a field, the less impact it has. 

If you’re going to keep using more water, you’ll have to install a wider or larger leach field, which is better capable of distributing the waste water out faster.

For example, if you’ve had your septic tank pumped but it’s still backing up, you might need to increase capacity. 

See also  Where Do Basement Floor Drains Go? [Answered]

5. Poor Installation 

If you’ve recently had a septic tank installed and are already having issues, the problem is most likely that the system has been poorly installed.

Here, anything from improper angles to bad pressure or a poor bacterial ecosystem starter can cause your septic tank to overflow and back up. 

In most cases, if you’re having issues within 6 months of installing the system, it’s a problem with the installation. That’s true whether you only get backed up after a heavy rain or if the tank itself is full. 

How To Fix 

You’ll want to inspect the full septic system to see what went wrong and where.

Here, your problem might be any number of issues. For example:

  • Soil doesn’t percolate properly and must be replaced 
  • Angles from the main waste pipe are too steep and water does not flow well
  • The pressure on the tank is wrong 
  • The tank is too deep 
  • Your tank isn’t deep enough
  • The tank is installed tilted 
  • The angles from the main waste pipe to the septic tank are not steep enough and water flows too easily back to the house 
  • The drain field is not big enough for the system 

Essentially, there are many things that could go wrong. You’ll have to inspect the issue, figure out what’s wrong, and then make appropriate changes.

Importantly, that could mean fully digging up and reinstalling the septic tank. 

6. Damaged Leach Field 

If the leach field is crushed, damaged, clogged, or broken, it can cause your septic tank to back up. Here, most leach fields are made up of perforated systems of pipes.

Over time, these pipes can degrade, become clogged, or break. When that happens, water flow from the tank to the drain field will slow. Eventually, you’ll have a septic tank backup. 

How To Fix

Fixing a damaged leach field always means digging the field up. From there, you can inspect it to see if you can replace damaged parts or if you should replace the full system.

In most cases, digging a leach field up is the most expensive part of the process, so replacing it is often a good idea, unless it’s relatively new. 

Next Steps

There are dozens of things that can cause a septic system to back up. However, the most common include clogs and leaks. In each of these cases, it’s important to assess whether you can fix the issue yourself or if you need a professional to come in and help. And, of course, it’s important to decide if it’s more cost-effective to apply for a permit and do the work yourself or to have a professional do it with professional equipment. 

In some cases, such as with bacteria infusions, you can almost never do the work yourself – because you’ll have to test the existing content and make adjustments based on those results. In others, such as replacing the drain field, you can do the work yourself relatively easily, providing you take the proper safety precautions