Reading the specs for your TT, you have one, 30 gal grey and one, 30 gal grey tank. It is possible the shower and sink in the bathroom drain to the black tank. This is done for two reasons, 1, for ease of installation and thereby saving production expense. 2, to keep plenty of water in the black tank for proper draining and cleaning. Kitchen would then drain into the actual grey tank.
Best way to tell is with full hookups, run the sink and shower and verify if only the black tank fills.
2017 Cougar 279RKSWE
2007.5 Dodge Ram 2500 6.7 Cummins
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