The function and duties of the Erftverband are stipulated by the „Erftverbandsgesetz“:
- Research and surveillance of water management conditions within the Rhenish brown coal district
- Regulation of water runoff including compensation of flow conditions and safeguarding of flood runoff of surface waters or sections of waters within their catchment areas
- Maintenance of surface waters or sections of waters and their functionally related facilities
- Restoration of modified surface waters to their natural state
- Groundwater management
- Prevention, reduction, elimination and compensation of adverse changes to water management conditions and their associated ecological conditions caused by modification of the groundwater level within the Rhenish brown coal district
- Procurement and provision of water to ensure the current and future supply for the population and economy, and promotion of measures to reduce water consumption
- Wastewater treatment in accordance with the Northrhine-Westfalian water act
- Removal of waste associated with the duties of the Erftverband
- Prevention, reduction, elimination and compensation of adverse changes to surface waters due to wastewater or other causes
- Evaluation of water management conditions
