Handling of substances hazardous to water

Water body protection is vital for securing public health and the natural foundations of life, and as a prerequisite for economic development. To this end, water bodies must be safeguarded as an integral part of the natural environment and a habitat for animals and plants. Their management must benefit both the general public and, where the two can be harmonised, the interests of individuals, and avoid impairing their ecological functions.

One of the key tasks of the precautionary principle is to prevent substances hazardous to water being discharged from industrial installations and polluting surface and ground waters. This not only means preventing devastating damage such as the fire at the Sandoz company in Basel, fish mortality or contaminated drinking water, but also damage that is not immediately apparent, for instance negative impacts on water organisms like algae and small crustaceans.

What are substances hazardous to water?

Substances which are considered hazardous to water are defined according to their physical, chemical, human toxicological and eco-toxicological properties and cause adverse changes in water quality. They include most of the substances used in trade and industry, as well as in private households, for example oils, fuels, solvents, acids, lyes and salts.

These substances are divided into three water hazard classes (WHC) in accordance with chapter 2 of the ordinance on installations for handling substances hazardous to water (Verordnung über Anlagen zum Umgang mit wassergefährdenden Stoffen (AwSV)):

  • WHC 1: low hazard to waters (for example acetic acid, soda lye, alcohol or hydrogen peroxide)
  • WHC 2: significant hazard to water (for example heating oil, sodium hydrochlorite, iodine)
  • WHC 3: severe hazard to waters (for example waste oil, chlorinated hydrocarbons, benzene)

The classification provides the basis for graduated safety requirements for installations. The operator must arrange for classification of substances which have not yet been assigned a WHC. Substances which have already been classified can be looked up online at

Legal basis and responsibilities

The precautionary principle and thus the fundamental standard to be upheld by installations can be found in Articles 62 and 63 of the Federal Water Act (Wasserhaushaltsgesetz – WHG). The specific technical design of installations and corresponding obligations of operators, including the necessary procedures for notification and determination of suitability, are laid down in the ordinance on installations for handling substances hazardous to water (AwSV), which entered into force on 1 August 2017. The requirements set out in the federal ordinance apply to new installations from this date onwards. Operators of already existing installation must, for instance, comply with the review obligations, however, retrofitting the installations is only necessary when ordered by the competent authorities. The 2006 reform of the federal system gave the Federation a broader legislative competence making it possible to adopt a federal ordinance and to allow no deviation by the Länder on provisions governing installations and substances. The installation ordinances of the Länder are therefore being gradually repealed. The Länder are responsible for enforcing the AwSV.

Provisions on technical installations

The Federal Water Act lays down the national standard to be met by installations (for example oil tanks, filling stations, warehouses or distillery plants). Under the precautionary principle laid down in Article 62 (1) of the Federal Water Act, installations for handling substances hazardous to water must be designed, constructed, maintained, operated and decommissioned in such a way that no adverse changes in the properties of waters are to be feared. This is deemed to be fulfilled when the installation has put two safety barriers in place and the operator meets specific obligations, including monitoring.

Primary safety must ensure that installations and parts of installations where substances hazardous to water are located are leak-proof and can withstand mechanical, chemical and thermal strain. Leakages of substances hazardous to water must be recognisable.

Secondary safety is a further safety barrier which prevents environmental damage in the event that containers or other installation parts fail. Secondary safety includes collection trays and other retention equipment which, in the event of a leak, can safely collect substances hazardous to water without the need for human assistance.

Monitoring measures aim to determine whether the installation is still leak-proof and the safety systems are still functioning. They are also intended to ensure that hazards are identified and eliminated quickly and reliably. Monitoring is primarily the responsibility of the operators themselves, but they must also commission an external expert before operation begins and subsequently at regular intervals to undertake a review of the installation.

Installations must always be constructed and operated in line with best available technology (Article 62 (2) WHG). Best available technology also means the principles and solutions laid down in technical standards and provisions which have been tried and tested in practice and which are recognised by the majority of experts in the field. Best available technology includes, in particular, the technical rules on substances hazardous to water for certain installations (for example heating oil consumer installations) and designs (for example sealing surfaces) published by the DWA, the German association for water, wastewater and waste. It also includes the Administrative Provisions on Technical Building Regulations (VVTB), published by the DIBt (centre of competence in civil engineering), which are relevant for water pollution control. National construction products for series-produced parts and stationary installations for storage, bottling and shipping of substances hazardous to water, which have general technical approval and which ensure the requirements of water protection are met are considered suitable. Construction products, in accordance with a harmonised European standard, are deemed suitable when they fulfill all essential characteristics of the harmonised standard which are relevant for water body protection. Any characteristics which are lacking must be fulfilled by the entire installation.

Review of installations

In addition to monitoring by the operator, many installations are also subject to a review by an external expert before operation begins and subsequently at regular intervals. These experts must belong to a recognised technical support organisation (TSO). Any deficiencies in the installation identified in the course of these reviews must be eliminated without delay.


Pipelines are conduits which transport substances hazardous to water and which connect different plants across several premises. In the past, these were also subject to the Federal Water Act, but together with other pipelines are now covered by Articles 65ff in conjunction with Number 19.3 Annex 1 of the Act on the Assessment of Environmental Impacts (Gesetz über die Umweltverträglichkeitsprüfung, UVPG). The Pipelines Ordinance (Rohrfernleitungsverordnung) contains the special technical and organisational requirements for these pipelines. Key documents on this were drawn up by the Pipeline Commission (Ausschuss für Rohrfernleitungen, AfR).

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