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.

There are a number of different HWT methods that aim to remove microbial pathogens from drinking-water. These different treatment methods vary in their ability to remove the main classes of enteric pathogens that pose health risks: bacteria, viruses and protozoa. To assist Member States in the evaluation and selection of HWT technologies, WHO developed global recommendations, detailing criteria and guiding principles for evaluating HWT performance. These recommendations provide the basis for evaluating and classifying HWT into three levels of performance: 3-star (★★★); 2-star (★★) and 1-star (★), based on their ability to remove pathogens from drinking-water.