How can I find out whether a particular property is suspected of being contaminated? | Umweltbundesamt

The competent lower-level soil conservation authorities, which can usually be found at the Umweltverwaltung office of your Landkreis or your kreisfreie Stadt, maintain a so called Altlastenkataster (site contamination registry) or Verdachtsflächenkataster (registry of suspected contaminated sites). These offices are required by law to provide you with the relevant information in response to a legitimate query.