To disinfect your Platypus hydration system, fill it with a solution of unscented household bleach and water, using a concentration of 2-5 drops per liter of water. Close and swirl for 10 seconds. Squeeze the bite valve to flush the hose and valve, being careful to keep the valve opening over the sink. Leave filled overnight. Dump solution and rinse hydration system (including hose and bite valve) three times with hot water, then air dry.
Note: for an eco-friendlier option, use a chlorine-free, hydrogen peroxide-based bleach alternative.