Dosing plants according to this standard are used for the controlled addition of small flows of additives or reagents into various processes of waste water treatment or sludge treatment. Dosing plants according to this standard also include equipment for the preparation of the above-mentioned substances, which is carried out before the actual dosing to the process. This standard specifies special design principles for these dosing plants on wastewater treatment plants, namely for: - such structures or parts of structures where the requirement or function of the technical equipment must be taken into account and for; - technical equipment, where special technical and wastewater treatment plants-specific requirements must be considered during planning, construction and operation, and for; - safety requirements. This standard applies together with the general design principles according to DIN EN 12255-1 as well as together with DIN EN 12255-13. The general design principles also apply to those facilities for which no technical standard exists. This standard does not apply to general principles of construction and mechanical engineering, of electrical engineering, of safety engineering and of waste water treatment technology. This standard does not regulate general principles for equipment such as pumps and other versatile equipment.