Frequently Asked Questions What do you mean by sanitary sewer system? Sanitary sewer systems are the collection of pipes, pumps, lifts, and other equipment throughout town designed to handle and safely transport used water, body wastes, and toilet paper as sewage to its treatment plants. What kinds of problems do grease cause? Sewer backups are frequently caused by improper materials, including fats, oils, and greases being introduced into the sewer system by Town customers. How big a problem is this in Cary? From 50 – 80 percent of all sanitary sewer overflows are caused by accumulations of fats, oils and greases discharged to it from the preparation and serving of food. Where does the grease in Cary sewers come from? Many sources. In the food industry, "grease" often refers to fats and oils derived from animal and vegetable sources. These include meats, nuts, cereals, and beans as well as waxes and paraffins. How does Cary size Grease Interceptors? Click here to download Excel Spreadsheet [ Self Extracting Zip ]