If you are detecting a musty or mouldy smell in or around your kitchen sink, there could be a variety of reasons for it. Since you use this area to prepare your food, this is one of the least desirable places to have unpleasant odours. Luckily you can rid your kitchen sink area of this smell easily if you can diagnose the source of the odour.
The P-trap is the P-shaped pipe found beneath the kitchen sink that traps a small amount of water inside it to prevent the odours from the sewer or septic tank from creeping back up into your kitchen. If this trap ever dries out, it can result in a sewer smell that will be apparent throughout much of the house. But this isn't the only smell that might result from the P-trap. If food or other debris gets caught in the trap, mould or mildew could form even if the trap is still working to trap out sewer gas. The odour from these items stuck in the trap could be your problem. You'll need to take the pipe apart and clear it out to take care of the smell.
If your kitchen sink is equipped with a garbage disposal, the smell could be from food particles caught in the disposal itself. As the blades of the disposal spin, they sling a slurry of food particles inside the drain hole in your sink. If they are not properly flushed away, they can mould and a foul smell can result. After you have ground up food in your disposal, put a plug in the sink and fill the sink half full with warm water and a squirt of liquid dish soap. Pull the plug, and turn on the disposal to rinse it out.
Dish Cloths or Towels
Sometimes the sink is not actually the source of the mouldy smell in he kitchen, although it may seem like the case. Check your dishwashing cloths or dish towels. If they have been wet and sat around for a significant length of time, they may have become musty or mouldy. A quick smell of the cloths will make obvious if they are the source. Simply wash them to get rid of the odour.
If your kitchen sink is leaking, mould might be growing underneath. Check under the sink to see if there are drips from any pipes or seals. If even a small amount of water is dripping into the cabinet beneath the sink, it could grow mould and result in a strong odour in a short time.