What Do I Do When My Septic System Backs Up?

Septic System Backup

The first thing to remember is not to panic! This happens to over 10,000 homeowners each year. With the proper troubleshooting techniques, you can determine the cause of the backup and then take action to resolve the issue. The septic system technicians at Aero-Stream® can help you diagnose the problem and recommend a solution.

You can call us anytime, any day at 877-254-7093 for a free consultation.

What are the causes of septic system backups?

There are several things that can cause a septic system to back up. To accurately diagnose the problem, you must understand what is going on. There is more water going into the system than is going out. Below are some potential causes:

Excessive water usage

Septic systems are designed to accept wastewater from the home. The size of the system is based on the number of bedrooms. The more bedrooms in the home the larger the tank must be and the larger the drainfield or mound needs to be. The industry uses a calculation to determine how much water the home is going to use. The standard is that each bedroom will have two occupants and they will each use fifty gallons per day. They then add in a factor of safety of 50%.

Therefore, as an example, a three-bedroom home would use 450 gallons of water each day (3 bedrooms x 2 occupants/bedroom x 50 gallons/day x 1.5 = 450). Therefore, if you have a system designed for 450 gallons per day and you are putting 550 gallons per day through it the water cannot be dispersed fast enough, and it will back up into the house or above the septic tank or above or around the drainfield or mound.

The excess water flow can be caused by poor water conservation habits such as long showers or doing two weeks of laundry all in one day. It can also be caused by mechanical malfunctions of water-using devices. As an example, a leaking flapper valve in a toilet can easily put an extra 2,000 gallons per day into the system! That is over four times the design flow rate of the system. A dripping faucet can put fifty gallons per day through the system.

Another common cause of excessive water use is water softeners and iron filters. These devices use a backwash process to clean the media that filters out the hardness or iron. Modern equipment is much more efficient than older equipment. If the machine malfunctions during a backwash or regenerative cycle it can add another 3,000 gallons of water into the system each day.

A clogged inlet pipe

A clogged pipe or a partially clogged pipe can cause backups. A clog can occur in the pipe between the home and the septic tank, or between the septic tank and the drainfield or mound. The pipe between the house and the septic tank should have a downward pitch of 1/4″ per foot of run. If the pitch is less than this the water and waste will not have enough velocity to overcome the friction in the pipe and not make their way to the septic tank.

If the pitch is too great, the liquids will travel faster than the solids. When this separation happens the solids eventually stop moving in the pipe and the liquids make it into the tank. Another common variation of this is a pipe that has a low spot that water and waste pools in. In all scenarios, the waste is stuck in the pipe and over time it builds up and will not allow any wastewater to flow into the septic tank. A clog can also occur in the inlet pipe if the inlet baffle in the tank is not in place.

A typical anaerobic septic tank has a thick layer on the surface of the water in the tank called a scum layer. The inlet baffle is designed to allow the wastewater to flow into the tank below the scum layer. If the inlet baffle is not in place the solids flowing from the house into the tank begin to pile up on top of the scum layer. Eventually, this waste will clog the end of the pipe and not allow any wastewater from the house into the septic tank and cause a backup.

In exceedingly rare occasions, roots can grow into the pipe usually at the joint where the pipe inserts into the tank. The solid waste from the home will get caught on the roots and cause the pipe to fill with solids and cause a backup. A clogged inlet pipe can be caused by a clogged outlet pipe. This will be discussed in the next paragraph.

A clogged outlet pipe

A clogged outlet pipe can cause a backup because it will not allow the partially treated wastewater (effluent) to leave the septic tank. If the outlet pipe is clogged it will cause the water level in the tank to rise above the normal level. There is typically a three-inch to four-inch fall between the inlet pipe and the outlet pipe. That is, the bottom of the inlet pipe is 3″ – 4″ above the outlet pipe. The typical inlet pipe is three inches in diameter. So, when the tank level rises about 5″- 6″ the inlet pipe becomes submerged.

At this point, the velocity of the wastewater coming into the tank hits the stagnant water in the tank and abruptly stops. As the water level in the tank rises 7″ – 8″ it is not backing up into the inlet pipe. Now the velocity of the incoming wastewater is stopped in the inlet pipe. Now, the solids begin to accumulate in the inlet pipe and eventually clog the inlet pipe. When the water level in the tank is high enough to submerge the inlet pipe you may hear gurgling pipes, drains, or toilets. The gurgling is caused because the tank can no longer vent properly.

When one gallon of water enters the tank from the home it must displace one gallon of air from the tank. This air travels up the inlet pipe above the wastewater and exits the soil stack on the roof of the house. When the inlet pipe is submerged it will not allow the air to flow freely so it builds a little air pressure inside the septic tank. When the pressure gets high enough it overcomes the water flow and burbs a slug of air into the inlet pipe.

This same phenomenon happens when you pour water out of a jug. When you tip the jug upside down the water flows rapidly and then suddenly stops because air must get into the bottle to displace the water that left. Once the air is back in the bottled water begins to flow for a brief moment and then the process of airflow repeats itself until all the water is out of the bottle. A clogged outlet pipe can be caused by an outlet baffle that is not functioning as designed or simply missing.

The scum layer begins to build up on the bottom of the outlet pipe. When this happens the water level in the tank rises a little allowing the scum layer to get a little thicker on the bottom of the outlet pipe. Eventually, the pipe builds up with the scum layer debris and clogs the pipe. Foreign material that should not be flushed down the drain can clog the outlet pipe. Examples of foreign materials are feminine napkins, “flushable” wipes, baby wipes, cigarette butts, grease, and hair.

It is extremely rare that roots can cause a clogged outlet pipe unless the pipe is completely filled with roots. The water flowing out of the septic tank does not have any substantial solids in it so it will not get caught up on the roots.

A failing drainfield or mound

A failing drainfield or mound can cause a backup because it won’t accept any additional water, so the tank levels rise. The scenario of elevated tank levels described above will occur when the drainfield or mound is failing.

What Are The Solutions To A Backed-Up Septic Tank?

The solution to a backed-up septic tank depends on what is causing the issue. The first thing that you should do is locate the septic tank cover. The septic tank cover is usually twenty-four inches in diameter or less. Or the septic tank cover could be square or rectangular. Most tanks have at least one septic tank cover. If the tank has only a single cover it is typically located above the outlet baffle of the tank. If you are lucky the system was built with a septic tank riser, so you do not need to do any digging.

If you must dig down to locate the cover, you can expect it to be only a few inches below the surface to several feet below the surface. May tanks have two septic tank covers. The second cover will typically be located above the inlet baffle. If you do need to dig down to expose the septic tank cover, I suggest that you install a septic tank riser. The septic tank riser will bring the cover to the surface so this will be the last time you have to dig!

Once the cover is located and exposed remove the cover from the tank. Many times, the covers are made of heavy concrete so you may need a pry bar to remove the cover. Once the cover is removed you can inspect the inside of the tank.

You should never leave the sight of a septic tank with the cover removed. An open tank is a safety hazard that exposes the risk to children and pets of falling into the tank.

If you can see the inlet and or outlet baffle, probe a long stick into the baffle to see if it is clogged. Many times, this technique will dislodge the clog. If the tank level is too high and you cannot see the inlet or outlet baffle you should have the tank pumped. Have the pumping company watch and listen for water running back from the drainfield. This would indicate that the pipes are not actually clogged but the drainfield or mound is failing. Many times, the pumping company will have a mirror on a stick and a flashlight. They will use these tools to see if the inlet baffle is intact and in good working order.

While the tank is being pumped down, flush the toilet, and run some water in the house to determine if the inlet pipe is clogged. If the water flows freely into the tank after it is pumped the problem is not likely the inlet pipe. If the water does not flow freely from the house to the tank after the tank is pumped the issue is a clogged inlet pipe. This pipe will need to be snaked from the inlet baffle if you have access to it or from the house side.

Many times, a cleanout port is located in the inlet pipe outside of the building between the house and the tank. Look for a cleanout port. If there is no cleanout port and you do not have access to the inlet baffle the pipe can be snaked from inside the house. Remove the toilet that is closest to the septic tank and run the snake down the pipe. After the pipe is cleared, you will need to determine the cause of the clog.

If there is water running back from the drainfield or mound during pumping, it is likely that the clog was caused by the failing drainfield and elevated tank levels. If the tank levels were not elevated the cause of the clog could be improper pipe pitch or a sagging pipe. This can be determined by having the inlet pipe video scoped. A plumber can run a video camera down the pipe to determine if there are any sags that wastewater pools in.

The plumber can use a transit level to determine the pitch of the pipe between the home and the septic tank. Sags or improper pitch need to be corrected by excavating the inlet pipe for its length and setting the proper pitch. If the inlet or outlet baffle is missing or broken it should be repaired or replaced. If you cannot reach the inlet baffle or outlet baffle from outside of the tank you should hire a professional to make the repair. The repair will need to be made from inside the tank.

Septic tanks contain deadly hydrogen sulfide gas. A person can be overwhelmed in seconds from this gas and cause immediate death.

The professional will take proper precautionary measures and don protective breathing gear while inside the septic tank. If there is run-back from the drainfield or mound during pumping it is likely that the clog was caused by a failing drainfield or mound. As we started with, do not panic!

Call us immediately at 877-254-7093 so we can discuss our solution to resolve failing drainfields and mounds. Do not let them dig before calling us!

If you would like to learn more about how a drainfield or mounds fail, check out our recent blog titled “I am Told My Septic System Has Failed, Now What?“.

As you have learned, there are many causes of septic backups. Some require more work than others to resolve. But with some knowledge and support from Aero-Stream® we can assist with resolving your problem. Whether it is diagnosing the cause of the backup or restoring your failed drainfield or mound, our FREE technical support is always available to you!

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