First, take the sending unit out and plug the filler neck hole. Then, take your garden hose with a sprayer and hose the thing out through the sending unit hole. Dump all of the water out and let it dry. It should be good to throw out, but I doubt the garbage man will take it. Drop it off at your local scrap yard, they probably have a pile of them. Is it too wasted to re-use?? If it doesn't leak, it can be cleaned and resealed using the Eastwood gas tank kit, or just cleaned out using muriatic acid from the hardware store if it's just rusty inside. I have cleaned and re-used many tanks over the years using these 2 methods. Good luck with your project. Geof