Indexes have been developed worldwide. One of the most widely known is the National Sanitation Foundation Index WQI- NSF which was developed by Brown et al., 1970 for United States rivers and has been applied and validated in several international studies.
A nivel mundial se han desarrollado diferentes ICA, entre los que se destaca el de la National Sanitation Foundation ICA NSF, desarrollado por Brown et al. 1970 para ríos de Estados Unidos y ampliamente empleado y validado o adaptado en diferentes estudios internacionales.