Newby..

We just got back from 4.5 days out with our KZ hybrid - very small tanks. Our site had electric and water, but not sewer. We managed this time to fill the grey and black tanks with just the two of us. I got a 12 gallon wheely tank at Camping World (Good Sam discount, woo hoo...) and was able to empty the grey tank to let us keep on showering and doing dishes. Great addition to the stash of camper stuff that is quickly growing in my garage. I did not have to empty the black tank, though, as it did not get full until we were getting packed up this morning, so we just used the local facilities until I could make it to the dump. However, the dump was OOO, oh no! The nice folks at the campground let me turn around and go back to an empty full hook up site to take care of business before leaving to come home - they even provided a hose to rinse everything off. Nice folks at Chocorua KOA in NH - highly recommended, especially if you are camping with four legged family members.

Edit: Our tote is grey, not blue. Also, the 12 gallon is small, but larger than the tanks on our small trailer, so I can't over fill accidentally. I would say get the smallest one that is larger than your largest tank. The 12 gallon is small enough that I can lift it wen full and put it in the back of the pickup truck without having to "tow" it to the dump site...so that is convenient on campsites with unimproved roadways.