Wastewater produced on campus includes dilute wastewater of experimental origin (4th or later rinsing water), office wastewater and rainwater. Basically wastewater in UTokyo discharges into public sewer system, where we need to meet the discharge standard set by Japanese law and local government ordinance. Even wastewater that derives from daily-life activity (such as food-origin wastewater) can violate the standard. In addition, not only wastewater from laboratory that contains hazardous substances but also rinsing water of lab-ware up to 3rd times must be collected and treated by ESC in UTokyo. You should not throw into sinks unless you are sure that the wastewater is not hazardous to human health and environment. The quality of wastewater that flows into public sewer from UTokyo is regularly monitored.