The secondary research process involved comprehensive analysis of regulatory databases, industry publications, beverage market reports, and authoritative health and environmental organizations. Key sources included the US Food & Drug Administration (FDA), Environmental Protection Agency (EPA), European Food Safety Authority (EFSA), International Bottled Water Association (IBWA), Beverage Marketing Corporation, International Council of Bottled Water Associations (ICBWA), World Health Organization (WHO) Guidelines for Drinking-Water Quality, US Geological Survey (USGS) Water Resources Division, National Resources Defense Council (NRDC), Centers for Disease Control and Prevention (CDC) Healthy Water Program, EU Drinking Water Directive Database, UN Food and Agriculture Organization (FAO) AQUASTAT, National Institute of Standards and Technology (NIST), American Water Works Association (AWWA), International Association for Food Protection (IAFP), and national food safety authorities from key markets including China National Health Commission, Food Standards Australia New Zealand (FSANZ), and Health Canada. These sources were used to collect consumption statistics, regulatory compliance data, quality safety standards, packaging regulations, demographic consumption trends, and market landscape analysis for still water, carbonated water, flavored water, and functional/nutrient-enhanced water segments.