Water balance according to DWA-M 102-4

Professional verification of rainwater management for municipalities and planning offices

The water balance is a central instrument for evaluating the local water balance in the context of rainwater management. The DWA-M 102-4 Code of Practice provides the technical basis for this and is recognized by authorities throughout Germany as a binding standard.

As an engineering office specializing in municipal infrastructure projects, we support you in the preparation of your water balance according to DWA-M 102-4 – verifiable, comprehensible and oriented towards the requirements of your approval authority.

Aim and content of the water balance

The aim of the balance is to keep the deviation of the anthropogenic water balance from the natural state as low as possible. The balance covers the main processes of the water cycle:

• Precipitation (P)
• Evaporation (ET)
• Infiltration (I)
• Surface runoff (R)
• Intermediate storage (ΔS)

The water balance serves as mathematical proof of the effectiveness of measures such as green roofs, rainwater retention or infiltration. It ensures that a balanced relationship between water inflow and outflow is maintained during construction and planning measures.

Areas of application for municipalities

Municipalities and municipal companies are increasingly using hydrological balancing as a planning and management tool. Typical fields of application are

• Planning of new residential or commercial areas
• Evaluation and optimization of unsealing concepts
• Development of municipal drainage strategies (e.g. as part of IEK or KSK)
• Verification of discharges under water law
• Integration into funding applications and climate adaptation concepts
• Implementation of sponge city principles

In many places, the water balance according to DWA-M 102-4 is a prerequisite for obtaining planning permission or applying for public funding.

Our services

We support cities, municipalities, planning offices and project sponsors in all steps of the verification process. Our services include

• Collection and analysis of all relevant input data (KOSTRA, soil parameters, area types)
• Calculation of the water balance according to DWA-M 102-4
• Investigation of variants to optimize retention, evaporation and infiltration
• Preparation of verifiable documentation for approval authorities
• Support with integration into funding programs
• Expert advice on municipal rainwater management

Our documentation is technically sound, clearly structured and tailored to the requirements of the relevant approval bodies.

See also Wikipedia article on water balance