On 5/28/2021 3:42 PM, Thomas wrote:
What would cause a backfliw toilet to overflow when it rains?
Nefew just asked me. He said his toilet drain is thru the wall.


Ask nephew where the drain line runs and at what level. Could be the
drainpipe is filling up from other stuff draining into it and backing
into the toilet. Could be downspouts going into the drain for instance.
It is septic or sewer system?