We noticed this morning that whenever water is run (any where in the house) brown yucky water comes up through our downstairs bathtub drain. There is also water on the bathroom floor but I'm not sure where that is coming from. What would cause this? Yes, we have a septic system. We don't know when it was last flushed. We bought this house 2 years ago.
Thank you for any advice you may have.

We noticed this morning that whenever water is run (any where in the house) brown yucky water comes up thru our downstairs bathtub drain. There is also water on the bathroom floor but I'm not sure where that is coming from. What would cause this? Yes, we have a septic system. We don't know when it was last flushed. We bought this house 2 years ago.
Thank you for any advice you may have.
First things first! You have a blockage downstream from the tub. The solution would be toUnscrew and remove the overflow plate,(The one with the drain lever) and pull out the tub stopper. You now have a clear shot at the trap. The way you were going in through the drain it ran you square into a tee that you can't get around. Now feed the cable( 1/4" best or 3/3" with a small tip. You can rent a Ridgid K50 sink cable.) About 2' down you will run into the bend of the trap. Crank and push at the same time to work around it. Your blockage will be found in the lateral pipe going to the stack. You shouldn't have to put out more then 10 or 12 feet. I have found tub and shower clogs to be mostly hair and the worm should auger into it and pull it back. After you snake pour a few pans of boiling water down the drain. This will loosen the grease and flush the mess out into the main. On the average septic tanks are pumped every three to five years, Hope this helps and thank you for rating my reply. TOM