Double Draining - Planning the Bathroom Drains

We don't use a lot of water in our 2008 Airstream, we can go without a fresh water fill up for at least 5 days.  And I expect that our water use will remain the same for our 1955 vintage Airstream.
We do need a larger water tank than the missing original fresh tank that fit under the cabinet under the front window.

We are taking advantage of Vintage Trailer Supply's standardized water tanks, positioning the two tanks below the floor in between the frame rails.  Plumbing the fresh tanks in tandem will work really well for us.  The tandem gray tanks will hold the same amount of water, reducing the possibility of overflow which I really want to avoid!

Putting the tanks into their spots in the frame rails.

Close-up of the tank straps covered with a peel-and-stick waterproof membrane.

The street-side plumbing is for the bathroom lavatory sink and the shower drains.  They join together to drain into the new grey tanks.  Back in 1955 Airstream and other trailers did not have holding tanks for water coming from the sinks and shower, and water was just dumped on the ground.  Not very sanitary, and so I'm glad to upgrade our Flying Cloud.

 Cutting the cross members for the tandem tank fittings.

 










The cross members ready for the tank connector. Note: the step was painted with the gray topcoat over the POR15 rustproof paint.