1. General information and definitions

1.1 Water and pathogens

Natural waters contain a large number of compounds that can be classified by size (suspended matter, colloids, dissolved compounds such as organic or mineral matter, ionized or not). They also carry numerous micro-organisms, some of which can be pathogenic.

Tables A, B and C in [ ] present various bacteria, viruses and cysts that can be carried by water.

These germs may be responsible for harmless infections (e.g. gastro-enteritis, diarrhoea), but unfortunately sometimes for serious or even fatal infections...