Always keep fresh water in the reservoir. After a period of about one week water becomes stale and should be replaced with fresh water. Steaming with stale water can cause a foaming action. If this occurs, you should rinse your water tank thoroughly and refill with fresh water. Jiffy Steamer has a 3-pack liquid cleaner available for $18.00 plus shipping. We recommend that the liquid cleaner be used once every 6-12 months to remove sediment and mineral deposit build up. This build up can result from using hard water.