The “Trinkwasserverordnung” sets limit values for various microorganisms, including

• Escherichia coli (E. coli): An indicator of faecal contamination.
• Coliform bacteria: General indicators of water quality.
• Enterococci: Other indicators of faecal contamination.
• Clostridium perfringens (including spores): Indicators of past faecal contamination.
• Legionella: Bacteria that thrive in warm water and can cause Legionnaires’ disease.