Ziplock bags are very easy to clean and can always be hand or machine washed in hot soapy water. However, using very hot water and a harsh detergent can shorten the life of the bag, so you should be careful not to use too much detergent. Also, after emptying food from ziplock bags, always turn them upside down and clean them by pouring some soapy water into them. This way, you can be sure that the inside of the bags is clean.