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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 ecotoxicological properties. They 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 up into three water hazard classes (WHC) in accordance with chapter 2 of the ordinance on installations handling substances hazardous to water (Verordnung über Anlagen zum Umgang mit wassergefährdenden Stoffen (AwSV))

  • WHC 1: low hazard to waters (e.g. acetic acid, soda lye, alcohol, iodine)
  • WHC 2: significant hazard to waters (e.g. heating oil, formaldehyde, sodium hydrochloride)
  • WHC 3: severe hazard to water (e.g. 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 in the administrative regulation or on the internet at webrigoletto.uba.de.

Legal bases and responsibilities

The precautionary principle and the basic obligations of the operators can be found in Articles 62 and 63 of the Federal Water Act (Wasserhaushaltsgesetz, WHG). The specific technical design and corresponding obligations, including the necessary procedures for notification and determination of suitability, are laid down in the ordinance on installations handling substances hazardous to water, which entered into force on the 1 August 2017. From this date onwards, the new obligations on operators will apply, in particular with regard to applications for new installations and review obligations for existing installations. The 2006 reform of the federal system gave the Federation a broader legislative competence which makes it possible to adopt a federal ordinance and which allows no deviation by the Länder on provisions governing installations and substances. The installation ordinances of the Länder are therefore being gradually repealed.

Provisions on technical installations

The Federal Water Act lays down the national standard to be met by installations (e.g. 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 if measures for primary and secondary safety have been taken and the operator meets specific obligations, including monitoring.

Primary safety ensures that installations and parts of installations where substances hazardous to water are located can withstand mechanical, chemical and thermal strain. This means they must be leak-proof for the entire duration of operation in order to ensure that there is no discharge of substances hazardous to water.

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 vats and other retention equipment which function independently of primary safety and 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) Federal Water Act). 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 (e.g. heating oil consumer installations) and designs (e.g. sealing surfaces) published by the DWA, the German association for water, wastewater and waste (further information at www.dwa.de). It also includes substances constituting a hazard to water listed in the Construction Products Lists of the DIBt (German Institute for Construction Technology). National construction products for series-produced parts for stationary installations for storage, bottling and shipping of substances hazardous to water, which have general technical approval and which take the requirements of water protection into account are considered suitable (for more information go to www.dibt.de). Changes are expected to be made in the near future to the approval of construction products and their use in installations handling substances hazardous to water on the basis of a judgement of the European Court of Justice.

Review of installations

In addition to monitoring by the operator, many installations are also subject to a review by an external authorised expert before operation begins and subsequently at regular intervals. These experts must belong to a recognised technical support organisation (TSO). An overview of currently recognised TSOs can be found at www.lanuv.nrw.de (in German only). 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 20ff in conjunction with No. 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). These can be found online at www.bam.de.

Last update: 01.08.2017