When I bought my TT I was told I had a 45 gal grey tank. All of the specs on the dealers and companies web site say 45 gal grey tank. Specs on the brochure and papers I received show 45 gal grey tank. But -- I actually have 2 grey tanks - a 20 gal for the kitchen, and 25 gal for the shower/sink in the bathroom. Personally, I wish it was one big tank, but from what I understand there is a different tank for the galley because some campsites will not allow dumping the kitchen grey tank due to the food particles / scraps and impact on both the environment and local fauna.