A sour odour in your dishwasher can be caused by a variety of things. Food, lime scale and standing water can eventually develop an overpowering smell. To eliminate sour odours in your dishwasher, first determine the source. Once you know where it is coming from, you can clean it away and prevent it from returning.
Dishwashers remove food waste from dishes, leaving them clean and ready to use again. This food has to go somewhere, and although it typically goes down the drain as it's supposed to do, small food particles and residue can remain behind. These particles or residue can cause a sour odour if left for long periods inside your dishwasher. Clean the bottom of the unit with vinegar and rinse with hot water to eliminate the residue and the smell.
Sometimes dishes sit for a long period of time as you try to fill the machine before running it. This can cause a sour odour from the food remaining on the dishes. Occasionally the smell remains even after you've cleared away the dishes. To remove the smell, run the dishwasher through a cycle when empty, using detergent and 2 tbsp of vinegar.
If you seldom use your dishwasher, food residue and particles or moisture trapped in the unit can cause odours to develop. Combine 2 tbsp of vinegar with the detergent in your dishwasher's soap dispenser and run a quick cycle while the machine is empty. To prevent the odour from returning, periodically run an empty cycle to wash away odours and clean the bottom of the unit.
If your dishwasher isn't draining properly, dirty water can sit in the bottom of the unit and will eventually begin to smell sour. Check the drain hose for kinks. Read your dishwasher's manual and ensure the drain hose is properly installed. If the hose is connected to your sink's garbage disposal, the odour might be coming from there and not from your dishwasher. The odour can seep through the hose to the dishwasher, making it seem like your problem is there. Run the garbage disposal with ice to remove any particles of food that might cause odour.
Dirt in the Door
Inside the door hinge on most dishwashers is a rubber seal, located where the door meets the dishwasher. Food and grease can drop into this rubber area and may build up fast. This can lead to a rotten, sour odour as the food bits begin to decay. Dampen a cloth with lemon juice or vinegar and wipe the entire door area to remove all bits of food and grease residue. To prevent the build-up from returning, wipe the door and rubber seal after each use.
To prevent sour odours from returning, run your dishwasher through a cycle while empty at least once or twice a year. Pour 2 cups of vinegar or lemon juice into the bottom of the unit and run it through a normal cycle and do an extra rinse. For dishwashers that are used frequently, fill the detergent dispenser with vinegar or lemon juice and run a short cycle monthly. The vinegar helps to reduce lime scale and mildew build up. Sprinkle about 3 tbsp of baking soda in the bottom of the unit between uses to absorb mild odours.