I had bought a cleaning kit on sale that has a long skinny brush for the tube, a bigger brush for the inside of the container, soap, and a bent wire hanger device that hangs it upside down. I usually open the fill cap and hang the bladder with the hose hanging down with the hand valve open and the bite valve removed. A paper towl inside in the bottom one inch (formally top) collects the pooled water that will not drain. After a week of hanging it is usually dry. I take out the paper towel and seal it back up.