Reusing common plastic milk jugs to store drinking water is a tempting option. These containers are widely available, but they are designed for single-use, short-term containment of a perishable product. This raises significant questions about their safety for long-term or repeated water storage. The primary concerns revolve around the plastic’s chemical composition, the difficulty of achieving true cleanliness, and the container’s physical integrity over time.
Understanding HDPE Plastic
Milk jugs are almost universally made from High-Density Polyethylene (HDPE), designated by the recycling code #2. This material is generally considered safe for food contact and is free of chemicals like Bisphenol A (BPA). HDPE is non-reactive and does not readily leach substances into its contents under normal conditions. However, the plastic used for milk jugs is a thin-walled, single-use formulation not intended for the repeated stresses of cleaning and reuse.
The Challenge of Eradicating Milk Residue
The most significant safety concern when reusing a milk jug for water is the difficulty of achieving true sanitation. Milk contains fats and proteins that adhere strongly to the plastic surfaces, creating a nutrient-rich environment. This residue is an ideal breeding ground for bacteria, including potential pathogens like Listeria or E. coli. Completely removing this residue is difficult because the narrow neck and corners of the jug prevent thorough scrubbing. Furthermore, the container cannot be sanitized using high-temperature dishwashers or boiling water due to HDPE’s low melting point. Using strong chemical sanitizers is also problematic, as the plastic may absorb or degrade from these harsh substances.
Physical Limitations and Wear
Milk jugs are engineered to be lightweight and inexpensive, resulting in a thin-walled structure that lacks durability for repeated use. They are prone to cracking or developing stress fractures with repeated handling and filling. These small breaks compromise the container’s structural integrity and can lead to leaks. Repeated washing also causes microscopic scratches on the inner surface of the plastic. These imperfections trap organic residues and moisture, making the jug even more difficult to clean and sanitize effectively. The plastic also absorbs and retains odors, often imparting the faint taste of sour milk to the stored water.
Safer Containers for Water Storage
Consumers should choose containers specifically manufactured for long-term, repeated storage of drinking water. Containers made from materials like food-grade stainless steel or glass are excellent alternatives because they are non-porous, chemically inert, and easy to clean and sterilize. Glass will not leach any chemicals or absorb odors or flavors. Dedicated, heavy-duty water storage containers made from thick, food-grade HDPE or BPA-free polypropylene (PP, recycling code #5) are also reliable options. When selecting a reusable container, prioritize those with wide-mouth openings, which allow for thorough cleaning and sanitation, preventing microbial growth.