My kitchen sink is on a 50gallon septic system, and is backing up/slow drain. When the dishwasher runs it backs into the sink till the slow drain lets it go down. I you turn the sink on more than 15 seconds it backs up. Previous owners had a garbage disposal on the sink, I removed and use a strainer - the idea is nothing down the drain other than small particles that come off plates and thru the strainer of the sink/dishwasher.
Other bathrooms are on a 1000gallon system, drains into the front yard. No issues with this.
Had the systems inspected Feb 2018 when we bought the place, both were at "appropriate levels".
Map of tanks below. Red is bathroom 1k tank, blue is smaller kitchen sink:
I watched the pipe that goes from the house to the ground, it filled up and bubbled out with the cap removed with the water running. I tried to snake it, but my toilet snake is not long enough to do anything.
Time to get this kitchen sink tank pumped?? It would make sense to pump the big one too, right?
Sink backing up: