When running the shower the toilets and the drain for the furnace starts bubbling and backing up to the point of shower water coming out of the furnace drain and flooding the hall way... I have tried chemicals and last year we had our septic pumped out... it is only 2 adults and one child in the house... any suggestions as to what is going on and how to fix it.

Hi Zeelilfox

It certainly sounds like the main drain line is partially clogged. To confirm this, see if you can find the main drain cleanout plug and remove it. Once the cleanout plug is removed you'll flush the toilets or run the shower and watch the water flow out the drain. If water backs up to the cleanout plug and sits there for any period then the main drain line needs to be snaked to clear the drain (or septic is full again... though doubtful as you say).

If the main drain doesn't block up then the issue is inside the home and the lowest toilet will probably need to be removed and the drain snaked UNLESS you can find a cleanout at the base of the drain pipe just before it goes into the floor. In this case, you would remove that cleanout plug and snake the drain to the main drain cleanout. That should resolve the issue!

Check the main drain cleanout first...

Mark

Thank You so much I will try this!