The safety of bottled water is complex, involving federal regulation, manufacturing processes, and packaging materials. Consumer desire for the “safest” choice often stems from distrust of municipal tap water quality, fueled by contamination events. However, safety is not guaranteed by packaging alone; it depends heavily on the water’s source, treatment, and quality controls. Analyzing factors like regulatory oversight, purification methods, and potential chemical exposure allows for a more informed selection.
Understanding Bottled Water Regulation
Bottled water and municipal tap water are governed by two separate federal agencies. The Food and Drug Administration (FDA) regulates bottled water as a packaged food product. The Environmental Protection Agency (EPA) sets the safety standards for public drinking water systems.
Federal law mandates that the FDA’s quality standards for bottled water must be at least as protective as the EPA’s tap water standards. The FDA sets “Standards of Identity” and “Standards of Quality” for maximum allowable levels of over 90 contaminants. For example, the FDA sets the lead limit at 5 parts per billion (ppb) for bottled water, which is stricter than the EPA’s action level of 15 ppb for tap water.
The stricter lead limit reflects that bottled water avoids public lead service lines, a common source of tap water contamination. However, the EPA requires public water systems to test for contaminants more frequently and mandates public reporting of violations. The FDA does not require bottlers to use certified laboratories for mandatory testing or mandate the same level of public disclosure.
Water Source and Purification Methods
The source of bottled water is a primary factor in its final composition, and the FDA defines different types. “Spring water” must come from an underground formation where water naturally flows to the surface. It is typically treated minimally with filtration and ozonation to maintain its natural mineral content. “Mineral water” contains at least 250 parts per million (ppm) of total dissolved solids, with minerals naturally occurring in the source.
The category considered the most consistently pure is “Purified water,” often sourced from municipal supplies or wells. This water has been extensively treated to remove almost all contaminants and dissolved solids. Common purification techniques include distillation, deionization, and Reverse Osmosis (RO).
RO is one of the most effective methods, forcing water through a semipermeable membrane that filters out particles as small as individual ions. This process can remove up to 99% of dissolved organic compounds and metals. Purified water represents the highest standard of product consistency because the source is less relevant than the rigorous treatment it undergoes.
Key Contaminants and Health Concerns
The pursuit of the safest bottled water is complicated by contaminants introduced during bottling or leaching from the packaging. The most widely publicized concern is contamination by microplastics, tiny plastic fragments shed from the bottle itself, especially the cap. Studies often find microplastic levels in bottled water significantly higher than those in tap water.
These plastic particles are not inert; they can carry chemical additives like phthalates and bisphenols used in manufacturing. Chronic exposure to microplastics may be associated with inflammation and disruption of the gut microbiome.
Another significant concern is the presence of Per- and Polyfluoroalkyl Substances (PFAS), often called “forever chemicals” because they do not easily break down. PFAS are sometimes detected in bottled water, particularly when plastic is made from recycled materials, and their presence is linked to adverse health effects, including immune system and developmental problems.
Furthermore, the polyethylene terephthalate (PET) plastic used in most single-use bottles can leach heavy metals, such as antimony and lead, into the water. This leaching is accelerated when bottles are exposed to heat or direct sunlight during storage or transport.
Making an Informed Selection
The most actionable step a consumer can take is to scrutinize the label for third-party certification. Independent organizations like NSF International offer verification programs that go beyond standard FDA requirements. Certification involves an annual, unannounced audit of the bottling facility and extensive testing for over 160 chemical and microbiological contaminants.
Consumers should also pay close attention to the packaging material and storage conditions. PET plastic bottles must be kept in a cool, dark environment, as heat and sunlight increase the rate at which chemicals like antimony can leach into the water. Choosing water packaged in glass or using a reusable bottle made of stainless steel or glass minimizes potential exposure to plastic-related chemicals.
When selecting purified water, the label should explicitly state the method used, such as Reverse Osmosis or distillation, to confirm thorough treatment. If choosing spring or mineral water, look for brands that voluntarily publish their water quality reports. These reports provide insight into the natural composition and any potential contaminants present at the source.