WaterQuality

Water quality refers to the chemical, physical, and biological characteristics of water with respect to its suitability for a defined use, such as drinking, recreation, habitat, or industrial processes. Assessing water quality involves measuring parameters including pH, turbidity, dissolved oxygen, temperature, salinity (for marine and estuarine waters), conductivity, total dissolved solids, nutrients (nitrates, phosphates), metals, pesticides, and microbial indicators such as coliform bacteria and E. coli. Temporal and spatial variation is common, requiring systematic sampling and long-term monitoring.

Standards for water quality are established by national and international bodies. The World Health Organization provides guidelines for drinking-water quality, while many countries apply national standards and procedures. Water bodies are often assigned quality classes and monitored against targets set in frameworks such as the EU Water Framework Directive or national drinking-water regulations. Water quality indices combine multiple measurements into a single score to aid communication and decision-making.

Water quality is influenced by natural factors (geology, mineral content, natural ecosystems) and human activities (agriculture, industry, wastewater discharges, urban runoff, mining). Pollution can degrade taste, odor, color, and safety, and can harm aquatic ecosystems. Management aims to protect or restore water quality through source protection, pollution prevention, wastewater treatment, and water treatment for end users. Common treatment steps include coagulation, filtration, disinfection, and, for seawater or brackish sources, desalination. Emerging contaminants, microplastics, and antibiotic resistance pose new challenges.

Access to safe water quality is a public health priority; diverse regions face different challenges. Monitoring data supports risk assessment, policy, and environmental protection.