Precipitation water; application for a permit or permit amendment for direct discharge into water bodies

Rainwater that runs off from built-up or paved areas is classified as waste water within the meaning of the Water Resources Act (Section 54(1)(2) WHG).

The deliberate discharge of collected rainwater into a body of water (surface water or groundwater) generally constitutes a use of water resources that requires a permit under water law pursuant to Section 8(1) of the Water Act (WHG). A permit for the discharge of rainwater may only be granted if the volume and harmfulness of the effluent are kept to a minimum, in accordance with the state of the art and the relevant procedures applicable in each case (Section 57(1)(1) of the Water Act (WHG)).

In each individual case, it must be assessed whether and how the harmful effects of the stormwater discharge can be kept to a minimum.

In this regard, the generally accepted rules of good engineering practice set out in the relevant guidelines and technical data sheets of the German Association for Water, Wastewater and Waste (DWA) must be taken into account. The application of these rules is set out in detail in the relevant guidelines issued by the Bavarian State Office for the Environment (LfU). The necessary requirements are determined by the competent water management authority, which, acting as an official expert in water law proceedings, examines the application documents submitted.

If the assessment shows that the volume and harmfulness of the rainwater to be discharged – through any necessary measures, such as the creation of a retention capacity or appropriate pre-treatment measures – comply with the requirements for the specific discharge, the water law permit may be granted.

For the discharge of collected rainwater into a body of water (surface water or groundwater) (Section 9(1)(4) of the Water Act (WHG)), a permit is not required, subject to Section 8 of the NWFreiV and TRENGW or TRENOG, provided that the essential requirements are met:

• Rainwater is allowed to percolate into the ground over a wide area through a suitable layer of topsoil.
• Underground infiltration systems such as infiltration trenches, drainage pipes or infiltration shafts are only permitted if surface infiltration is not possible and appropriate pre-treatment has been carried out.
• A maximum of 1,000 m² of paved area may be connected to a soakaway system.
• Infiltration takes place outside water and mineral spring protection areas and outside contaminated sites and sites suspected of being contaminated.
• The rainwater to be infiltrated has not been adversely altered or mixed with waste water or substances hazardous to water.
• The rainwater to be allowed to percolate does not originate from areas where substances hazardous to water are regularly handled (with the exception of small containers of up to 20 litres).
• Rainwater running off uncoated copper, zinc or lead surfaces larger than 50 m² may only be allowed to seep into the ground after the water has been pre-treated via a suitable topsoil layer or via a treatment plant with type approval.

• Section 8(1) of the Water Resources Management Act (Wasserhaushaltsgesetz – WHG)
• Section 9(1)(4) of the Water Resources Act (Wasserhaushaltsgesetz – WHG)
• Section 15(1) of the Water Resources Act (Wasserhaushaltsgesetz – WHG)
• Section 18 of the Bavarian Water Act (BayWG)
• Regulation on the permit-free, environmentally safe infiltration of collected rainwater (Rainwater Exemption Regulation – NWFreiV)

• Rainwater Online Water Law (NOW)

  Accompanying website of the Bavarian State Office for the Environment

• Managing Rainwater

  Legal aspects and information from the Bavarian State Office for the Environment

• Technical Regulations for the Safe Discharge of Collected Rainwater into Groundwater (TRENGW)

  Announcement by the Bavarian State Ministry for the Environment and Health

• Technical Regulations for the Safe Discharge of Collected Rainwater into Surface Waters (TRENOG)

  Announcement by the Bavarian State Ministry for the Environment and Health

You can apply to your local district administrative authority for a permit to discharge rainwater directly. In general, the procedure is as follows:

• Please send your application for a permit, together with the required documents, to the relevant district administrative authority, preferably via the online procedure provided.
• The District Administrative Authority
  • checks that your application and supporting documents are complete and will contact you if any information or documents are missing,
  • will assess your application from the perspective of water management and water law and, where necessary, involve other bodies.
• You will receive either a permit or a notice of refusal.
• You will also receive a notice of charges.
• You pay the fee.

You can apply to your local district administrative authority for an amendment to your permit for the direct discharge of rainwater. In general, the procedure is as follows:

• Please send your application for an amendment to your licence, together with the necessary supporting documents, to the relevant district administrative authority.
• The District Administrative Authority
• • checks that your application and supporting documents are complete and will contact you if any information or documents are missing,
  • will assess your application from the perspective of water management and water law and, where necessary, involve other bodies.
• You will receive a notice of amendment to the permit or a notice of refusal.
• You will also receive a notice of charges.
• You pay the fee.

In the past, urban and residential drainage meant diverting rainwater as quickly and completely as possible in order to reduce the risk of flooding in the area. Nowadays, a ‘nature-based’ approach to rainwater management aims to disrupt the natural balance of the water cycle as little as possible. This brings not only water management benefits but also financial advantages. Rapid drainage of water impairs groundwater recharge and shifts the flood risk to downstream areas.

The guiding principle behind all construction work should be to interfere as little as possible with the water cycle, for example by using permeable surface coverings or green roofs. However, if such interference cannot be avoided, it can at least be minimised through nature-based, decentralised rainwater management. Therefore, lightly polluted rainwater (for example, from roofs and courtyards, private and local roads) be allowed to infiltrate on site, collected and reused (for example, for garden watering or toilet flushing), or at the very least retained locally and discharged in controlled quantities into streams and rivers. Provided the relevant technical regulations are observed, a permit is usually not required for the infiltration or discharge of rainwater.