Sewers backing up

Hi,
We are having a problem with our sewer backing up into our basement whenever someones takes a bath and drains the water out or when water is run for a long period of time. We have our septic pumped out fairly regularly and the problem does not seem to be related to that. Any ideas on what else the problem may be? Any help is very appreciated!
Thank you,
Jennifer

Your drain line to the septic tank is clogged. Contact a professional to auger it. Chemicals will not work, so don't waste time and money on them. DIY snakes are usually not effective on major clogs, so get a pro to do it.

plugged?

You don't know its the septic tank or not.

Best way to make a determination is to open the top of the tank where you septic man cleans it from.