Many people wonder if water can expire. While bottled water often carries an expiration date, pure water (H2O) itself does not truly spoil. Instead, its quality can diminish over time due to various external influences. These factors affect the water’s taste, safety, and freshness. Understanding these influences helps clarify why water might seem to “go bad” despite its stable chemical composition.
Understanding Water Expiration
The “expiration date” on bottled water typically refers to the container, not the water itself. The U.S. Food and Drug Administration (FDA) does not require expiration dates for bottled water, as it has an indefinite shelf life when stored properly. However, many manufacturers include “best by” dates, often around two years from production, to help with stock rotation and ensuring optimal taste.
This date indicates when the plastic bottle, commonly made of polyethylene terephthalate (PET), might begin to degrade. Over extended periods, especially with exposure to heat or sunlight, chemicals from the plastic can leach into the water, potentially altering its taste and quality. This compromise to water quality and safety is due to its packaging and storage environment.
Factors Affecting Water Quality
Chemical leaching from containers is a primary factor affecting water quality. Plastic bottles, particularly those made from polyethylene terephthalate (PET), can leach chemicals into the water over time. Antimony, a heavy metal used in PET production, can migrate into bottled water, especially when exposed to high temperatures. Other chemicals, including bisphenol A (BPA) and phthalates, also found in certain plastics, can leach into water, particularly when bottles are reused or exposed to warmth. The rate of this leaching increases with temperature and storage duration.
Microbial growth poses another concern for water quality. Contamination can occur once a bottle is opened or if water is exposed to the environment. Bacteria from human contact or the air can rapidly multiply in the water. Significant increases in bacterial counts have been found in opened water bottles within 24 to 48 hours, especially at room temperature. This proliferation can lead to an altered taste, odor, or potential health issues if consumed.
Water can also absorb odors and tastes from its surroundings. If stored near strong-smelling substances like cleaning products or certain foods, water can take on those characteristics. This absorption can occur even through plastic, as it is slightly permeable. Consequently, water might develop an unpleasant taste or smell, even if it remains chemically safe to drink.
Ensuring Water Safety and Longevity
To ensure water safety and longevity, adhere to specific storage practices. Store water in a cool, dark place away from direct sunlight and heat. High temperatures accelerate the degradation of plastic containers and increase chemical leaching. Also, keep water away from chemicals and solvents, as plastic bottles are slightly permeable and can absorb surrounding odors or vapors.
Choosing the right container is important for water longevity. For long-term storage, food-grade containers made from high-density polyethylene (HDPE) or BPA-free plastic are recommended. Glass or stainless steel containers offer more stability and do not leach chemicals, providing a superior option for preserving water quality.
Good hygiene is important, especially with opened water. To prevent microbial contamination, avoid drinking directly from bottles intended for storage or sharing, as this introduces bacteria from the mouth. For emergency water supplies, rotate water every six months to a year. This rotation ensures freshness and helps identify any potential issues with storage containers.