The worst thing one can do with a septic system is to have a sink drain garbage disposal grinding system. Sludge build up and very fast! Non-cooked/softened foods take more time to depose in the septic tank and also the greases off dishes and bones/bone pieces etc ran thru the sink disposal goes right into the septic tank with the other hard to breakdown foods stuffs. Then there's the paper products that are constantly flushed down. "How to kill a septic tank system fast"
Ever look into the removed septic tank plug/cap hole and see the thick grease that's floating on top? Then imagine the increasing sludge build up on the bottom of the tank. It's an education for sure and will tell you why you should be carefull as the what other than soiled water you drain into it. Sure does reduce the bacteria active capacity of a septic tank if caution of what goes into the septic tank and it's not sludge pumped out as often as it should be.
That doesn't mean human waste or reasonable gray water from an RV as it's nearly all simply liquid by the time it's dumped after sloshing about in the holding tanks all the miles of driving to get the RV home. RV'ers with Porta Potti's or cassett toilets knows how quickly the solids break down into simply liquid in the holding tanks with any decent chemicals in them. We've used a 5 gal Porta Potti in the winter that sits in the shower base in our TC's for 30+ years and I've have never seen anything but liquid come out when I dump it. NO chunks ever!