We live in CT with well and septic. A few years ago we started having an intermittent swamp like odor from the kitchen sink and adjacent dishwasher. It is so powerful that we have had to throw away some dishes & plates that seem to absorb the smell. This smell does not appear in any other locations in the house, laundry room, 2 1/2 baths, outside hoses, etc. Over the years we have bleached the pipes in the entire house more than once. We have replaced the water tank, garbage disposal, kitchen faucet, even the dishwasher as the stink seemed to begin with a hot water load of dishes, now appears to be cold water too. Only in the kitchen sink & dishwasher. We have not bleached the well as the water coming into the house from the well does not smell. We have installed a whole house charcoal filter. We have recently installed a water conditioner as we had a high level of manganese. (No bacteria or other alarming substances detected in 3 separate water tests). We have drained & bleached & rinsed the "boiler mate" hot water tank. The smell always returns no matter what we have done. Sometimes we have a few weeks of normalcy then it returns with no apparent trigger. I'm considering replacing the piece of copper pipe that connects the pipe in the basement to the sink/dishwasher or ripping walls apart to track the vent pipe but these are last ditch efforts. I would appreciate any advice as I'm at my wits end.