Pour out any leftover liquids that are in the canteen. Inspect the inside of the canteen with a flashlight and look for interior damages that may cause infection of the canteen in later uses.
Place your canteen into a pot of hot water on a low-heated setting, completely submersing the canteen and the interior with hot water. Wait approximately one hour to allow the dirt and grime to loosen from inside the canteen and to eliminate bacteria.
Place the canteen upside down to allow the excess water to run out and for the canteen to dry.
Apply a finger-full of soap detergent to the canteen cap. If the cap is complex, make sure you reach all the crevices of the cap to fully disinfect.
Run the cap under the hot water and rinse until all the soapy residue is removed from the cap.
Allow both the canteen and the lid to dry completely before storage. Failing to do so can potentially lead to mold and bacteria growth.