The waste water drain hose on my '07 x210 is ridiculously short so as to fit in the also ridiculously short storage tube mounted on the road-side wall of the camper going into the space beneath the refrigerator. I too, bought a longer hose and appropriate fittings to make things right. I mounted a 5' length of 4" PVC tube with end caps to the rear bumper. Quickly found that the fittings on the ends of the new hose WERE TOO LARGE FOR THE PVC TUBE! Will be getting some square tubing as Eagle did above to remedy the situation. Luckily, the 4" PVC tube was left over from another project so I'm not out of any cash.When the black tube under the camper is provided for the sewer hose storage, the diameter is to small to store the tube with ends on the hose attached. Also it's a cheap, thin flimsy hose.
After one use, I purchased a Rhino sewer hose with ends .. like this: https://www.walmart.com/ip/Camco-39...SkC00LP-y8_tXkwPc50aAo2QEALw_wcB&gclsrc=aw.ds
I also purchased some 4" or 5" square white plastic channel, affixed it under my camper to store it - far superior the the factory hose and storage tube.