What to do with an RV that has been sitting for a while? Hi everybody. My name is Mark. I am a newcomer to the site and also a newcomer to full-time living in an RV. My question is I purchased a 2017 keystone toy hauler that has been sitting since January. What do I do about freshwater, gray water and black water storage tanks. I am picking the RV up Wednesday morning. The trailer was bought new in September 2017. Lived in until January and then put on a ranch and left on occupied. I am told the tanks are empty but what do I need to do to prepare them for my use. Thanks for all your Advice and help. Advice and help