It's common knowledge that choosing the cold water setting on your washing machine is the most energy-efficient way to do laundry. With advancements in laundry detergent, many of us opt to wash everything in cold water. However, a recent study published in the Daily Mail showed there were high amounts of bacteria still on undergarments after being washed in cold water. By washing your undergarments in hot water with white vinegar and detergent, you can effectively kill the bacteria. Bedding for young children who still have accidents in bed should also be washed in hot water.