On my Bullet 210RUDWE, the fresh water and city water connections are side by side on the port side just forward of the forward egress window and lead inside to the water pump. When I removed the access panel just aft of the laundry chute to inspect the water pump, however, I discovered a third hose which appears to come in just above the fresh water and city water hoses. Any idea where that third hose comes from and where it goes? It doesn't come from outside near the other two hoses and isn't connected to the water pump. I thought it might be related to the black water tank rinse system, but that appears to enter the cabin under the bathroom sink (identified by the anti-siphon valve). My owner's manual doesn't include a plumbing schematic and, of course, I haven't been able to locate a phone number for the Keystone factory in Pendleton, OR.
Any ideas?