I was just wondering why we're getting suds in our basement toilet, from bathtub upstairs. Thank you.

I was just wondering why we're getting suds in our basement toilet, from bathtub upstairs. Thank you.

Because you have a partial clog downstream from the basement toilet that'[s causing backpressure backing up the discharge from above. The solution would be to snale the line, either from a cleanout on the stack or pull the basement toilet and snake from there. Good luck, Tom