Proportion of wastewater generated by households and by economic activities which is safely treated based on treatment ladders as defined by the SEEA: (http://unstats.un.org/unsd/envaccounting/water.asp, and International Recommendations for Water Statistics and IRWS: http://unstats.un.org/unsd/envaccounting/irws/irwswebversion.pdf) compared to total wastewater generated by households and economic activities.