The cistern flush toilet is usually made of porcelain and is a mass-produced, factory-made user interface. The flush toilet consists of a water tank that supplies the water for flushing the excreta and a bowl into which the excreta are deposited. Excreta are flushed away with water stored in the cistern (depending on the type between 6 to 20 litres per flush). Cistern-flush toilets provide a high level of convenience for the user but their installation can result in a significantly increase of the fresh water consumption and increase of wastewater to be collected and treated. Dual flush toilets (with a smaller flush-volume for urine), low-flush toilet and urine diverting toilets are available in order to reduce the amount of generated blackwater.