portable tank

I bought one of those several years ago, used it once at home, then realized that nearly all of the campgrounds we went to were either full hookup or had no dump station.
After it gathered dust under the shop workbench for about 5 years, I sold it in a rummage sale.
I'm just glad I realized there were no dump stations before I filled the thing! That would be a really bad thing, to have that thing full and no place to dump it!