We have a tri level home and our up stairs shower is fine except when we run the water the lowest level bathroom floods. The water is coming from the bottom of the toilet cause I sat and watched it. What cold be cause of it cause we don't have septic tank we have sewer line. Please help! Thanks

You have a partial blockage downstream from the lower bath that must be snaked and cleared. You can snake this from several locations,
1) From an basement stack cleanout if you have one.
2)) from the lavatory roof vent. Put out enough snake to reach the base and 20 feet more. Rent a sewer machine to do this . **OR**
3) Pull the toilet and snake from there, Good luck, Tom

3) Pull the toilet and snake from there, Good luck, Tom



I like this suggestion , with water coming from the bottom of the toilet, the wax seal needs replaced anyway. Good luck

Thanks Tom. My husband went to get a snake and is planning on removing the toilet. We will see! I hope it works!

with water coming from the bottom of the toilet, the wax seal needs replaced
About wax seals. Wax seals were never designed to contain back pressure caused by a blockage, especially the head pressure coming down from a upper floor.
The flush is directed past the wax seal by a horn that projects down past the closet flange. This insures a seal between the floor and the bowl keeping out sewer gas.
Cheers, Tom