Wash your gym water bottle in warm, soapy water and use a bottle brush. Any washing-up liquid will do, however, silicone and plastic bottles can take on the scent of the soap, so it may be best to choose a fragrance-free option. Some water bottles are dishwasher safe, so make sure you check this out beforehand. Even if your gym bottle can go in the dishwasher, we still recommend washing smaller parts, like straws, to prevent a build-up of bacteria.