My mother is on a septic system. A problem has developed which so far has no solution. The kitchen sink gurgles and has a sewer smell when the washing machine drains. Also, when it rains a lot the kitchen sink backs up with water. She had the lines dug up and replaced, the grease trap cleaned, the vent on the roof checked for blockage, and the pipes under the sink replaced. None of that helped at all. After all of that money outlay we are still confused as to why the kitchen sink gurgles and smells like sewer when the washing machine drains since in no way are they connected. And, why the sink backs up with a lot of rain. Any other suggestions are greatly appreciated.
Sounds like the sink has no vent and when wash machine drains it syphons the trap, install a vent. I dont know what kind of Plumbing job you got but if the rain backs up into the sink meams the rain water is getting in the pipe some where, have a back water trap installed in the pipe that will stop water from backing up into sink, not good but best i can tell you without seeing job unless you can draw it up and send it to firstname.lastname@example.org