We have a 225g polypropylene tank that we use for sap storage. I intend to rinse it out but it's impossible to get all of the water out of it, even turning it upside down water gets trapped in the molded in areas.
What is the best way to store for the summer? Do I need to worry about mold? Theoretically it should just be plastic and water so nothing for bacteria to feed on. Do I just leave it and rinse again next season?