RV Gray Water Drains into Black Holding Tank

We have a brand new motorhome produced by a major manufacturer. We like most everything about the rig but one thing about this particular coach really bothers us. Our shower drains into the black tank. Now normally we could dry camp (in our old rig) without needing to empty our black tank for a couple of weeks. Not true here. We have to dump this black tank every single day. We could just give up on showering, I guess. When we contacted the manufacturer about the issue they pretty much told us to take a hike. Are there other motorhomes out there with this same problem and are there any regulations which govern the installation of black tanks at the manufacturing level? If we can't correct this hang-up our $150,000 coach will pretty much be worthless to us, which is just what we've found the manufacturer to be.
Daniel, (Appleton, WI) 

Wow, I’m so sorry to hear of your difficulty with the manufacturer Daniel. It’s unfortunate, but it is permissible for RV manufacturers to allow a liquid fixture to drain into the black water holding tank and still satisfy the requirements of the NFPA 1192, Standard for Recreational Vehicles. This is typically predicated by the design of the floor plan. In my opinion, not the optimum situation.

Most makers, thankfully, do keep the black and gray waste systems separated and relegated to dedicated holding tanks. In those few instances where a gray waste fixture does drain into the black holding tank, typically it will be an infrequently used device like a lavatory sink. Based on your description, it sure sounds like a very poor waste system design.

Now having said that, in some instances, it is possible to re-route the shower drain to the existing gray water holding tank, or better yet, to a newly installed third tank. A competent RV technician will have to inspect the existing waste system to see if that option is feasible. All drains must enter the holding tank at the top of the tank, so gravity filling from the side or bottom of the holding tank is not allowed. A thorough inspection will determine how best to accommodate the modification. I wish I had a more definitive direction for you. But try to find an experienced RV repair facility in your area that can make the alterations. All is not lost yet!