In Germany low / medium level waste, which is classified here as radioactive waste with negligible heat generation, will be disposed of in the Konrad underground repository. The construction and the operation of this nuclear facility required authorization by different fields of law, i.e., by nuclear law, mining law and water law. Whereas the nuclear law considers solely radiological aspects, the relevant permit issued according to the water law considers the impact of radioactive as well as non-radioactive harmful substances. The Federal Office for Radiation Protection (BfS) as operator of the repository and permit holder has (a) to record the disposed of radioactive and non-radioactive harmful substances and (b) to balance them. To meet these requirements BfS has developed a concept, which led to a site specific solution. Threshold values were defined for recording and for balancing the harmful substances. It had to be verified that by disposal of radioactive waste packages according to these values an adverse effect on the near-surface groundwater can be excluded. The Lower Saxony Water Management, Coastal Protection and Nature Conservation Agency (NLWKN) as the responsible water law regulatory authority approved the operator’s concept as appropriate to comply with the requirements of the Water Law Permit. Nonetheless, collateral clauses were imposed to assure this.