: My toilet in the basement of my newly constructed home backs up whenever the washing machine is used. The washing machine is on the 1st floor and is located directly above the basement toilet and Im sure its on the same directly connected to the toilet drain. The drain pipe is under the poured concrete floor and runs out in a fairly direct line to the septic tank in the back yard. Is there any kind of one way valve that can or should have been installed to stop the suds from coming up into the toilet bowl and overflowing onto the floor. The toilet is a new kholer low flow model.Bob, I will tell you that its pretty hard to have an idea on this one without taking a look see. That said let me take a stab at it, first thing I would do is determine is why does the upstairs connect to the basement. The basement should be pumped up tp the main line. Very rarely run at basement level. Now if you in fact do not have a sump basin that is pumped up to the main level from the basement I can them guess that the upstairs drops from above and connects to what is the main sewer line at basement level. Now does that toilet sit directly on the main line and if so is the fitting under it installed correctly. Or is the toilet set a distant off the main line before it exits the house in which case maybe the main line fitting to upstairs was installed incorrectly. Now if you cant see any of these pipes either can the Licensed Plumbing Contractor who ultimately shows up to correct your problem. The best answer is a video inspection of the sewer line from the laundry machine sewer clean out, and diagnosed by that same Licensed Plumbing Contractor in your area. Good Luck.
