Laundry may smell sour when it is left in the washing machine for too long or when the washer is overfilled. Front-loading washing machines can also cause odors when mold and mildew are present inside the machine.
In order to remove odors and dirt from clothing, water must be able to move freely in the washing machine. Wash small loads of laundry in hot, soapy water to prevent odors caused by overfilling the washing machine. Clothing should be placed in the dryer or line dried immediately after washing.
Clothing that remains damp, such as towels thrown into a hamper after use, may develop mildew or mold, and smell sour after washing. Towels and other clothing should be allowed to air dry before storing in a hamper, or washed immediately with hot, soapy water and 1/2-cup Borax. Add 1 cup of white vinegar to the rinse cycle to remove the odor completely.
Front-loading washing machines may cause clothing to smell sour if mildew or mold has developed inside the machine. To get rid of mold or mildew, clean the gasket around the door of the washing machine with hot, soapy water, then remove and clean the detergent and softener dispensers. Rinse the gaskets and dispensers thoroughly. Start the washer on a regular wash cycle without clothing, then add 1 cup of chlorine bleach after the washing machine has filled with water. Commercial washing machine cleaning tablets or 1 cup of baking soda can be used in place of chlorine bleach.