If the backup is actually caused by an overflowing septic tank, call a septic system contractor. But the problem may be a clog in the drain pipe running to the septic tank, in which case you need a plumber. To determine which it is, locate the cleanout and open it. The cleanout is a short PVC pipe located between the house and the septic tank that sticks out of the ground or is flush with it, and has a threaded, removable cap.

   Look down into the cleanout. If there is no standing water in the bottom, then the problem is a clog between the house and the cleanout. You should call a plumber. But standing water in the main drain pipe at the bottom of the cleanout riser indicates that you have either an overflowing septic tank or a clog between the cleanout and the tank.

   If you know the location of your septic tank and are willing to dig up and remove the lid of the tank, then you can look down into the open tank for a final answer. This step is not recommended for the faint-hearted. Also, do you put your face close to or in the tank opening, because you can be overcome by methane gas; and, for safety, it is recommended that you have someone with you when you open the tank. 

    If the liquid level in the tank is high (near or at the top of the tank), then you need to call a septic contractor. A normal level indicates a clog between the cleanout and the tank—work for a plumber.

   If you can’t find the cleanout or open the tank to check the liquid level, then it’s not possible to be sure who to call. But the age of the system will help you determine the most likely right choice. If your septic system is 25 years or older, call a septic tank contractor. If newer, the odds are better that it’s a plumbing problem.

    Also, see our blog posts How often should I pump out the septic tank? and What can I add to my septic tank to help it work better?

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  To learn more about septic tank systems, see these other blog posts:

• What are the building code requirements for gray water reuse in Florida?

• Why do septic tank contractors want you to get rid of your kitchen disposal? 

• Do I have to get a larger septic tank when I build a home addition? 

• Where is the septic tank? Are you going to inspect it? 

• Can a house have more than one septic tank?

• What is the difference between gray water and black water in the plumbing code? 

• Is it alright to disconnect the washing machine drain from the septic tank and divert it to the ground in the yard?

   Visit our PLUMBING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.