Basement bath backing up, have not located clog. Amateurs request advice.
We have a split level with 4 different levels. The problem is in the basement bathroom, on the lowest level. The kitchen is almost directly above that, on the main level. On the opposite side of the house there are 2 bathrooms on the highest level and a bathroom & laundry room on the level below that. We have no drainage problems on that side of the house.
There is a recurring problem of the toilet, sink and shower in that basement bathroom backing up. When the sink or shower are used, the water will rise and then very slowly drain back down. We cannot use the toilet in this bathroom or it will force water up into the shower as it drains. Today when the toilet was flushed, it simply filled all the way up to the top of the bowl, then very slowly drained, leaving a very small amount of water in the bowl. At times, food from the kitchen sink/garbage disposal upstairs comes up the shower and sink when the water rises. We have stopped using the garbage disposal and washing food down the kitchen sink in order to minimize this problem. If we fill the kitchen sink full up and then drain it all at once, it will force water (and any food that has gone down the drain) up the shower and sink in the basement bath. In retrospect, this toilet seemed to clog very easily from the time the house was built 16 yrs ago.
A kind plumber acquaintance came and snaked out the main drain line all the way to the street. He did not find a clog there. He did determine that our lowest level drains by gravity out to the sewer line at the street and there is no lift pump involved. He felt that the problem was not in that particular line.
There are probably no tree roots involved; there are no trees in the area of the drain line.
We do not have any experience with plumbing and are on a very tight budget. We would be most grateful for any help. Possible ideas to try ourselves? Or how to find a plumber? Thank you so much!