Are your tanks empty? How many grey tanks do you have? If you have 2 grey tanks I would pour water down your kitchen sink with the valves closed, then I would open each valve until you see the water come out of the tank then I would label it. Same thing with the black tank, just pour water down the toilet, then you will know the other valve is for your shower and bathroom sink..Hope this helps.
2006 F250 psd CC Sb 4x4 with B&W companion.
2007 Wildcat 28rks 5'ver
2005 Harley Davidson
2009 Weimaraner "Dog"