u/backtul

We have a Grand Lodge that we live in full time in the summer. We are hooked onto a permanent site. Our gray tank stays open at all times to drain directly into the lines. Recently, whenever I drain my kitchen sink the most awful smells fills the camper. You can smell it outside as well whenever this happens. It does not happen when using any other water source in the camper (bathroom, shower, washer, etc.). I have flushed copious amounts of water down it to try to help, filled up the tank and flushed it, all to no avail. Am I able to fill it with water and then put bleach down and let it set for a while?

Open to all advice.