Long-distance coaches empty their toilets using a sanitary pump-out system at specialized depots or rest stops. The onboard toilet is connected to a "black water" holding tank located in the lower chassis of the bus. This tank contains chemicals that break down waste and neutralize odors. When the coach reaches a maintenance facility or a designated bay at a bus terminal, a large-diameter waste hose is connected to an outlet valve on the side of the vehicle. The waste is then sucked out into an underground septic system or a larger treatment tank. After emptying, the tank is flushed with water and a fresh dose of chemical "blue" liquid is added to prepare the system for the next journey. Modern coaches are equipped with sensors that alert the driver when the tank is reaching capacity. This closed-loop process is designed to be hygienic and environmentally friendly, ensuring that no raw sewage is discharged onto the roads, unlike the "drop-chute" systems used on older trains.