Vinegar has worked for me very successfully in the past. It takes longer for it to work, but it will clear a drain. I've used it in shower drains to dissolve hair, and I suspect it will dissolve food or other organic clogs as well. It just takes a while for it to work. Pour it in the drain and let it sit. Put more if needed. It's a natural product and won't hurt the pipes or tanks. And, as referenced, it anything spills when you are dumping the tank, it won't hurt anything there either. I'm not a big fan of the chemicals available today. Not only can they cause severe skin/eye burns, they can and DO also put off noxious gases that in a confined space like an RV can be deadly.
1999 Holiday Rambler Endeavor, 36' Gasser
Triton V10, Ford F53 Chassis
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