welcome to the forum its a great place to get your questions answered. You need to provide some information so the forum members can help like the year, model, and make of your rig.
__________________
Retired Navy
Jake my sidekick (yellow Lab) 10/04 - 05/20
2017 RAM 2500 CC 4X4 Cummins Diesel
2016 Flagstaff 26 FKWS
AF&AM & El Korah Shrine of Idaho
do you live where there are mud dobbers? wasps? go up top of rv, remove pipe vent cap, push a garden hose down pipe , if it stops not far in , turn on water and flush vent pipe. if it fills up to top of pipe ," cloggged". let set. if water goes down slowly , re fill. you may have to push a rod down pipe to clear pipe. clog will drop to waste tank. flushed a gallon bucket full out of a trailer once.