potability

Potability is the measure of whether water is fit for human consumption. In public health contexts, potability implies that water is safe to drink and to use for cooking and personal hygiene, without causing harm or having unacceptable taste, odor, or appearance. Authorities assess potability by comparing water quality against established microbiological, chemical, and physical criteria.

Microbiological criteria focus on the absence or safe levels of pathogens. Common indicators include coliform bacteria and Escherichia coli. Chemical criteria set maximum contaminant levels for substances such as lead, arsenic, nitrates, pesticides, and disinfection byproducts. Physical criteria cover turbidity, color, taste, and odor. Potability is dynamic; a source water meeting criteria at the time of sampling may become unsafe if treated improperly or if distribution system conditions deteriorate.

Assessment and protection of potable water typically involve treatment and monitoring. Water may undergo coagulation and flocculation, sedimentation, filtration, and disinfection, with additional processes for specific contaminants (ion exchange, reverse osmosis, aeration). Ongoing monitoring by utilities and certified laboratories verifies compliance. Public systems often implement residual disinfectant levels and maintain system integrity to prevent recontamination.

Regulatory frameworks vary by country but share common objectives. International guidance includes the World Health Organization Guidelines for Drinking-water Quality; national standards include the U.S. EPA National Primary Drinking Water Regulations and the European Union Drinking Water Directive.

Limitations and context: potability indicates safety for drinking under established conditions but does not guarantee taste or appearance, and it depends on continuous monitoring and proper system operation.