Drains are dewatering means which are used to collect, receive and convey wastewater. These include bathroom, floor/roof, balcony, roof and cellar drains as well as yard and gutter drains.

Basic standard for gravity drainage systems within buildings according to DIN EN 12056
This standard has been applicable since 1st July 2001. It establishes the general requirements and calculation methods throughout Europe. However, since many countries have their own drainage system, and thus impose specific requirements on construction and safety, the respective national regulations remain in force. In Germany this is DIN 1986-100. It controls the specific design requirements and the usual installations.
In accordance with this DIN standard, section 8.2.1, sanitary facilities in buildings which are used by an ever-changing group of people or which are open to the public, such as hotels and schools, have to be fitted with a floor drain with odour trap. Bathrooms in homes should be fitted with a bathroom drain. In addition to the floor-draining function, the bathroom drain also protects against flooding and penetration of water into the structure owing to overflowing bathtubs or defective washing machines. Balconies and loggias must also be fitted with a floor drain.