Got a picture? Only hose I can think of that's usually open ended is the winterizing suction hose. Usually ties in near the pump where you can shut of water tank supply valve, and open the valve to the suction hose.
John and Rebecca Dickson
Emma-7 / Little John-5 / Iva-1
Full Timing Again, Rev B
2013 Ford F-350 Lariat CC LB PSD
2015 SOB TT - With OC's Awning Poles (#8)
At least in Heaven, RVs will be perfect, and I won't have to keep fixing them.