Not cleaning the washing machine
Skin cells, dust mites, and stains from clothing can remain in the washer drum as well as on the lid, door, and detergent dispenser. This causes the clothes to be washed in dirty water, and eventually they will become smelly.

Solution: For a top-loading machine, start by selecting the longest and hottest wash setting. When the drum is almost full of water, pour in one liter of vinegar and one cup of baking soda, leave the lid open, and let the mixture settle while the washer is idle for at least an hour.

Meanwhile, clean the lid and any other visible nooks and crannies. Close the lid, allowing the wash cycle to begin. Repeat the cleaning stage with vinegar and baking soda if necessary, then wipe the inside of the washing machine and leave the lid open until the washing machine is completely dry.

For a front-loading washer, pour a solution of 1/4 cup baking soda and water into the detergent box, and pour 2 cups of vinegar into the drum.

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