A couple of years ago I discovered the same issue with our Roadtrek 2000 190P water fill hose just hours before heading out on our first trip of the Spring for the B-9 Rally. I got on the ground to take a look and found that the original flex hose that was badly cracked and leaking in several spots due to age.
Ack! No easy way to add bleach into the tank for sanitization. Luckily, I had a new drinking quality water water hose handy, so I cut one end off at a slight angle. Then I snaked it through the existing leaky flex hose all the way to the supply tank and then left about 5 inches sticking out before cutting the rest of the hose off. I inserted a new tapered funnel into the hose end to add bleach into the tank and added fresh water using the normal water connection. The rear door closes fine with the hose in place.
Made it on the road only an hour later than planned.
Steve