Toilet closest to washing machine gurgles and backs up when washing machine drains.
When the washing machine drains, the toilet in the next room gurgles and the bowl partially fills. I have taken these steps:
Ran hose down vent pipe on roof. No backup noticed.
Had plumber snake from outside wall cleanout by washing machine and 1/2 bath toilet to city sewer line in alley, about 162 feet. Some cast iron pipe corrosion felt and tree roots.
Had city water department run camera down sewer outlet in alley - clear 10 feet back into my property, and clear on their end leaving the property.
Removed washing machine drain hose at wall and hand snaked several times, seeing soap suds and bits of cotton from garments washed when snake removed.
Noticed soap suds coming from drain fitting at wall when next load was run.
