If your insulated mug has developed a smell that survives washing, the mug is almost certainly fine. The problem is in the lid, and specifically behind the seal.
Take the lid apart
Nearly every travel lid has a silicone gasket seated in a groove. It pulls out – usually with a fingernail, occasionally with the corner of a teaspoon. Behind it is a channel that fills with coffee and never drains, and no amount of rinsing the assembled lid reaches it.
Pull the gasket, wash both parts separately with hot soapy water, and let the gasket dry fully before you refit it. Refitting a wet gasket traps water in the same channel and you are back where you started within a week.
For a smell that has set in
Fill the mug with hot water, add a tablespoon of bicarbonate of soda, drop in the disassembled lid parts, and leave it overnight. Rinse in the morning. This works on coffee, tea and protein-shake residue.
For stubborn cases, use white vinegar instead of bicarbonate, but do not mix the two – they neutralise each other and you get salty water.
What not to do
- Do not put an insulated mug in the dishwasher unless the manufacturer says it is safe. Dishwasher heat can compromise the vacuum seal, and once that goes the mug is a heavy cup.
- Do not use bleach. It pits stainless steel and perishes silicone.
- Do not use a wire brush. Scratches in the interior give residue somewhere to hold on.
Preventing it
Rinse the mug the same day, not the next morning. Store it with the lid off so the interior dries. Both take seconds and remove the problem entirely.
If a mug that used to keep drinks hot for six hours now manages two, that is a failed vacuum rather than anything you have done – contact us and we will sort it out.