We had this issue last summer in our 197 before we sold it. I sanitized the tank and lines but still had the smell. I flushed the hot water tank with fresh water and still had the problem. I finally figured it must be coming from the grey water tank. I picked up some grey water tank treatment and the problem disappeared. After some more searching, it could have been the plumbing vent under the sink also? We never had the smell after.
2015 Jayco 24FBS Elite Jay Flight
2013 Chevrolet Silverado 2500HD 4X4 6.0L 3.73 Axle
HD Trailering Package with Integrated Brake Controller
Equal-i-zer Hitch 10k/1000