DIN 1988-300:2026-07 - Draft

What is DIN 1988-300 about?

DIN 1988-300 describes calculation methods for the dimensioning of drinking water installations and specifies how pipe diameters for drinking water pipes and circulation systems are determined. The aim is the hydraulic design of cold and hot water systems, taking into account supply reliability, drinking water hygiene, user comfort, and cost-effectiveness. The standard covers cold drinking water (PWC), hot drinking water (PWH), and circulation systems for hot and cold water (PWH-C and PWC-C).

What content does the standard cover?

DIN 1988-300 defines the calculation principles for pipe network calculation in drinking water installations and describes the determination of pipe diameters, volume flow rates, pressure losses, and circulation systems. It also includes requirements for documenting calculation results as well as reference values for pipe materials and resistance coefficients.

Topics covered at a glance:

• Pipe dimensioning in drinking water installations
• Hydraulic calculation of cold and hot water systems
• Pressure loss, flow rate, and pipe network calculations
• Hot and cold water circulation systems
• Ring lines and resistance coefficients
• Documentation and verification

Why is the standard relevant in practice?

DIN 1988-300 supports planners and contractors in designing drinking water installations in accordance with the applicable standard. By calculating peak flows, minimum flow pressures, pressure losses, and pipe friction values, drinking water pipes can be dimensioned with hydraulic reliability. The standard therefore provides a sound basis for pipe dimensioning, pressure loss calculation, and the design of complex drinking water systems.

At the same time, correct dimensioning of pipe diameters and circulation systems helps ensure drinking water hygiene and enables economical operation of the system.

What changes have been made compared with the previous edition?

Compared with DIN 1988-300:2012-05, the draft has been revised and expanded in several areas. The most important changes include:

• Removal of the previous concept for forming usage units
• Inclusion of a differentiated calculation method for ring lines in floor distribution systems
• Revision of the calculation of hot water circulation systems using Methods A and B
• Revised and expanded tables for resistance coefficients
• Addition of a calculation method for cold water circulation systems (PWC-C)
• Update of normative references
• Editorial revision of the standard

The introduction of calculation methods for PWC-C systems is one of the most important technical additions in the draft version.

Target audience

DIN 1988-300 is aimed in particular at:

• Specialist planners, engineers, and designers for drinking water installations and technical building services
• Sanitary planners and specialists in drinking water, supply, and building services engineering
• Experts, assessors, and inspection engineers
• Installers, system builders, and executing plumbing, heating, and air-conditioning specialist companies
• Operators of larger drinking water systems and those responsible for building services and facility management

Conclusion

DIN 1988-300 is one of the key standards for the hydraulic calculation of drinking water installations and the standard-compliant pipe dimensioning of drinking water pipes. It provides the basis for calculating pipe diameters, pressure losses, peak volume flows, and circulation systems. By including calculation methods for cold water circulation systems (PWC-C), the draft version significantly expands its scope and strengthens planning reliability for modern drinking water installations.