Lint, grease and improperly installed drains are the primary offenders for this problem. In most homes, the kitchen and laundry drains are connected. When the lint from the laundry drains meets the coagulated grease buildup (from dish soaps, food products and other natural compositions such as pipe material and bacteria), a paper-mache like substance forms, causing blockage. Rootering and/or hydrojetting of the drain is recommended with follow-up treatment to help maintain free-flowing drains.