Wastewater is generated by domestic, commercial, agricultural, and other uses of water in nearly all economic and daily life sectors. Wastewater from commercial sources is pretreated, if required by the source area, and conveyed via the public sewer system to municipal wastewater treatment plants for further treatment (indirect dischargers). The treated wastewater is then discharged into surface waters.

In wastewater source areas that have corresponding de minimis regulations and requirement regulations—and where only a notification rather than a permit is required for discharge—discharges are monitored by competent authorities in accordance with the Indirect Discharger Ordinance. This applies, for example, to separator systems for treating wastewater containing mineral oil, to amalgam separators in dental practices, or to dry-cleaning facilities.

Authorized bodies may operate within the scope of their authorization. Authorizations may be limited to specific areas of testing or be time-limited.

Approvals from other federal states, as well as from other member states of the European Union, a signatory state to the Agreement on the European Economic Area, or Switzerland, are considered valid approvals if their equivalence has been determined by the approving authority and published in the State Gazette for the State of Hesse.