You can take a few steps to ensure that your travel mug won't leak as you take a sip. If the lid has a silicone seal above the threads, make sure it's lying flat. Also, make sure the lid is screwed on tightly and evenly on the thread. Although most travel mugs on this list are dishwasher safe, some recommend hand-washing them regardless, as the dishwasher's heat and water pressure could damage the lid's airtight seal. The jury is out on that—use your own discretion, and don't feel bad if you'd rather chuck everything in the dishwasher.