Yes, water bottles fit fine with the ten inch spacers you see in the DIY. you can see my huge 32oz water bottles in the video i think. I do however thin that the front bottom of the tubs hardly scrape the water bottles, I'll go check.... they do, but just hardly! I put the divider in side ways because I wanted to have to load the food into the front and not the side, and it works fine. Im sure once I have more rats i will not even need piece that keeps it compact, because im sure i'll need all the space!

Edit** I also like the black tubs, I think they look neater!