How to save tank space?

You'll probably never fill up your 30 gal black tank, but the gray tanks can fill up quickly, especially with showers. We have a 32 gal Barker tote for the gray tank and a 60 gal "Water Boy" with pump for replenishing the fresh water. We conserve somewhat, but like to use our facilities in the trailer to their full potential, especially when the grand children are along. It's a bit of an investment, but the two items I mentioned can take the worry out of running out/filling up. As to the Water Boy, it's a bit pricey but there are other methods you can rig up like water bladders, extra water jugs, etc. One member even bought a huge ice chest with a spigot on the bottom that serves dual purpose as a water hauler (with small pump) and a conventional ice chest. The only time this method does not work is if you're staying at a campground with no fresh water or dump station, which is rare. Good luck.