Offenbach am Main has set out to become a "sponge city". This means that rainwater must be stored on site and not simply flushed into the sewage system. Water is a valuable commodity for all municipalities. Hundreds of city trees, our parks and green and recreational areas are already affected by dehydration because groundwater is not available in sufficient quantities. At the same time, the number of flooding events is increasing. It is also crucial for the local climate in the city how much water seeps away and is available locally for evaporation. On Thursday, the city councillors will decide on the introduction of a statute for rainwater.
"With these bylaws, we are taking another step towards becoming a sponge city. Rainwater is not only useful and important to us, but we are also relieving the burden on the sewage system and protecting our city from flooding during heavy rainfall events or mitigating the consequences. This also improves the situation for our trees and green spaces. In addition, the water that seeps away on site cools our environment. It evaporates and improves our microclimate on hot days. Providing relief for our city on hot days is vital for our citizens, especially babies, children and the elderly," explains Mayor and Climate Officer Sabine Groß.
The climate function maps for the city of Offenbach show that the overheating of our city has been increasing for years. Our groundwater level is sinking due to a lack of precipitation and green structures are dying off.
"The statutes replace and supplement an important enforcement instrument that was removed from the Hessian Building Code in 2018. This meant that we had no means of checking the handling of rainwater within the procedures under the building regulations - but at the same time we have tasks under the Water Resources Act and the Hessian Water Act to ensure the sustainable handling of precipitation. As part of the city's climate strategy, it is also an important concern for us," adds Heike Hollerbach, Head of the Environment Department.
Statutes define decentralized management
On around six pages, the bylaws define the decentralized management of rainwater in accordance with legal and technical requirements. The statute provides better protection for existing bodies of water in the future. Uncontaminated precipitation is used to recharge groundwater and should be kept in the areas instead of flowing into the sewage treatment plant.
Precipitation on roofs and green underground garages with drainage areas of 30 square meters or more are regulated for this purpose. Protection of existing buildings applies to all buildings that already existed before the bylaws were passed. The regulations of the bylaws are only binding for new buildings, extensions and additions. Insofar as existing development plans provide for deviations from these rainwater regulations, these take precedence over the bylaws.
Polluted runoff from balconies, terraces, courtyards and traffic areas that is susceptible to contamination is treated in a separate procedure in accordance with federal and state regulations.
Important for property owners: Rainwater must always be managed on the property. Either by recycling it yourself or by infiltration and evaporation. This can be done with rain barrels, cisterns or by infiltration in various technical designs such as infiltration trenches or troughs. Rainwater can be used for toilet flushing, cooling, washing and cleaning systems or for watering green spaces, for example. Where possible, clean rainwater can also be fed into existing streams. Another option is green roofs with additional layers that temporarily store water and later gradually release it back into the plants and the air.
Under certain conditions, joint water management of several properties is also possible. The Lower Water Authority at the Office for the Environment, Energy and Climate Protection of the City of Offenbach is responsible for checking the management of rainwater.
If you have any questions about the other rules in drinking water protection areas, please contact the staff of the Lower Water Authority by e-mail at umweltamtoffenbachde
Office for Environment and Climate
Stadt Offenbach am Main - Kaiserpalais
Kaiserstraße 39
63065 Offenbach
Notes on accessibility
Further information
KOMM parking garage, IHK Offenbach parking garage, Rathaus parking garage, public parking spaces on the banks of the Main
- +49 69 80652557
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