Globally, nearly two billion people use either unimproved drinking-water sources or improved sources that are faecally-contaminated. Close to half a million diarrhoeal deaths in low- and middle-income countries are attributed to inadequate drinking-water, and the vast majority of these deaths occur among children under 5.

Household water treatment and safe storage (HWTS) is an important public health intervention to improve the quality of drinking-water and reduce diarrhoeal disease, particularly among those who rely on water from unimproved sources, and in some cases, unsafe or unreliable piped water supplies. Further, safe drinking-water is an immediate priority in most emergencies, and HWTS can be an effective emergency response intervention.

The WHO International Scheme to Evaluate Household Water Treatment Technologies (“Scheme”) was established to evaluate the microbial performance of household water treatment (HWT) technologies against WHO health-based criteria. The results of the Scheme evaluation are intended to guide HWT product selection by Member States and procuring UN agencies.