Stormwater; Application for a permit or a permit amendment for direct discharge into water bodies

If you wish to allow stormwater to infiltrate the ground or discharge it into a surface water body, you generally need a water permit.

If you wish to modify a project for which you already hold a water law permit, you must apply to the competent district administrative authority for an amendment to the permit.

Rainwater is water that drains from built-up or paved areas.

Surface water bodies include rivers, lakes, canals, streams, ditches, and ponds.

The permit requirement for discharge into groundwater does not apply if no adverse changes to the groundwater are expected. The discharge is considered harmless if the “Regulation on the Permit-Free Harmless Infiltration of Collected Stormwater” (Rainwater Exemption Ordinance – NWFreiV) and the “Technical Rules for the Harmless Discharge of Collected Rainwater into Groundwater” (TRENGW) are complied with. This is generally the case when the stormwater drains from areas with low pollution levels and is not discharged into protected areas. The permit requirement for discharge into surface waters does not apply if the “Technical Rules for the Harmless Discharge of Collected Rainwater into Surface Waters” (TRENOG) are complied with.

If necessary, you can use the online procedure to determine whether you need to apply for a permit. There are online procedures that determine, upon completion of the form, whether the discharge is exempt from permitting or whether you must apply for a water law permit. You can then submit the application digitally to your district administrative authority.

The permit specifies the type and extent of use. It may be subject to conditions and ancillary provisions. Unlike an authorization, a permit can be revoked by the district administrative authorities.

Stormwater that is collected and drained from built-up or paved areas is considered wastewater under the Water Resources Act (Section 54(1)(2) WHG).

The deliberate discharge of collected stormwater 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 Resources Act (WHG). A permit for the discharge of stormwater may only be granted if the volume and harmfulness of the wastewater are kept as low as possible by adhering to the state-of-the-art methods applicable in each case (Section 57(1)(1) WHG).

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

To this end, the generally accepted rules of technology set forth in the relevant guidelines and working papers of the German Association for Water, Wastewater, and Waste (DWA) must be taken into account. The application is specified in the corresponding guidelines of the Bavarian State Office for the Environment (LfU). The necessary requirements are determined by the competent water management office, which, as an official expert in the water law proceedings, reviews the submitted application documents.

If the review determines that the volume and harmfulness of the stormwater to be discharged—through any necessary measures, such as the creation of a retention volume or appropriate pretreatment measures—meet the requirements for the specific discharge, the water law permit may be granted.

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

• The stormwater is infiltrated over a wide area through a suitable topsoil layer.
• Underground infiltration systems such as infiltration trenches, infiltration pipes, or infiltration shafts are only permitted if widespread infiltration is not possible and appropriate pretreatment is carried out.
• A maximum of 1,000 m² of paved area may be connected to an infiltration system.
• Infiltration must take place outside of water and mineral spring protection areas and outside of contaminated sites and areas suspected of contamination.
• The stormwater to be infiltrated must not be adversely altered or mixed with wastewater or water-polluting substances.
• The stormwater to be infiltrated does not originate from areas where water-polluting substances are regularly handled (except for small containers up to 20 liters).
• Rainwater from uncoated copper, zinc, or lead surfaces larger than 50 m² may only be infiltrated after the water has been pre-treated via a suitable topsoil layer or after pre-treatment via a treatment system with type approval.

You can apply for a permit for the direct discharge of stormwater at the district administrative authority responsible for your area. In general, the procedure is as follows:

• Send your application for a permit along with the required documents to the relevant district administrative authority, preferably using the online procedure provided.
• The district administrative authority
  • will verify that your application and documents are complete and will contact you if any information or documents are missing;
  • reviews your application from the perspective of water management and water law and, if necessary, involves other agencies.
• You will receive a permit or a notice of denial.
• You will also receive a fee notice.
• You pay the fee.

You can apply for a change to the permit for the direct discharge of stormwater at the district administrative authority responsible for your area. In general, the procedure is as follows:

• Send your application for a permit amendment along with the required documents to the competent district administrative authority.
• The district administrative authority
• • will check that your application and documents are complete and will contact you if any information or documents are missing,
  • reviews your application from the perspective of water management and water law and, if necessary, involves other agencies.
• You will receive a notice of permit amendment or a notice of denial.
• You will also receive a fee notice.
• You pay the fee.

In the past, urban and residential drainage meant diverting stormwater as quickly and completely as possible to reduce the risk of flooding in the area. Today, a “nature-oriented” 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 of all construction activities should be to interfere as little as possible with the water cycle, for example through permeable surface coverings or green roofs. However, if intervention cannot be avoided, it can at least be limited through nature-based, decentralized rainwater management. Therefore, lightly polluted stormwater (for example, from roof and yard areas, private and municipal roads) be allowed to infiltrate on-site, collected and reused (for example, for garden irrigation or toilet flushing), or at least retained in a decentralized manner and discharged into streams and rivers in controlled quantities. In most cases, no permit is required for the infiltration or discharge of rainwater, provided that the relevant technical regulations are observed.