mileshuff wrote:
Highly likely there is a 2nd grey water tank with a valve not located in the compartment with the other valves. My 5'ers grey tank manufacture specs combines the two grey tanks into one listing. Does not show them individually. Mine has the shower grey and black tank valves located together in a compartment near the front of the trailer. The kitchen sink grey tank valve is located further back towards the rear of trailer.
This would be my guess also...if the black spec is 35 gallons and the gray is 70 gallons, the odds are that there are two gray tanks at 35 gallons each (that's the way my 318SAB is; listed as 76 gallon gray, but, is actually two 38 gallon tanks)and that there is an "extra" handle back by the wheel well. On my 318SAB, there are two handles forward for the bathroom gray and the black tank, while the galley gray tank's drain handle is under the trailer, just forward of the wheels.
Take a look under the trailer towards the rear, depending on where your kitchen is; mid-trailer mounted, look for handle around the wheels, if the kitchen is rear mounted, look around the rear of the trailer. It will be "under" the trailer in either case and can be easily missed unless you know it is there.