Old ice can make you sick, but the danger does not come from the water itself “going bad” after being frozen. The health risk results from external factors, where the ice acts as a storage medium for contaminants introduced before or during freezing and storage. Freezing temperatures do not eliminate all microbes; any pathogens present remain dormant and become active once the ice melts in a beverage.
Sources of Contamination in Freezer Ice
Contamination is a concern because freezing halts microbial growth but does not kill all harmful bacteria, viruses, or molds. Certain hardy pathogens, such as Listeria monocytogenes, can survive and remain viable even when frozen. Once the contaminated ice melts into a drink, these dormant bacteria become active, posing a risk of foodborne illness.
One common source of contamination is the quality of the water used, especially if it is non-potable or unfiltered tap water containing impurities. However, the most frequent path for pathogens is through cross-contamination within the freezer environment itself. Raw meat juices, which can contain bacteria like Salmonella or E. coli, may drip onto uncovered ice trays or storage bins.
Improper handling also introduces biological contaminants. Using dirty hands, scoops, or trays that have not been thoroughly cleaned can transfer microbes from kitchen surfaces into the water before it freezes. Even after freezing, the ice remains vulnerable if it is stored next to unwrapped or leaking foods, allowing airborne particles or defrosting liquids to settle on the ice surface.
Degradation of Ice Quality Over Time
Ice stored for too long will experience a degradation in quality. This phenomenon is due to sublimation, where solid water molecules bypass the liquid phase and turn directly into a gas. This process causes the cubes to shrink and become cloudy, compromising their texture and density, similar to “freezer burn.”
Ice is susceptible to absorbing volatile organic compounds from the air within the freezer. Storing ice next to foods with strong odors, such as garlic or fish, causes the ice to absorb these smells and flavors. When this old ice melts, it releases the absorbed odors and tastes into the beverage, creating an off-flavor described as “stale.” These sensory changes do not pose a direct threat of sickness.
Safe Practices for Making and Storing Ice
To mitigate the risks of contamination and quality degradation, always start with clean equipment. Regularly wash ice trays, scoops, and storage containers with hot, soapy water. Using filtered water can also improve the final quality of the ice by reducing mineral content and potential impurities from the tap.
Once frozen, ice must be transferred from open trays into an airtight container or a sealed, heavy-duty freezer bag for long-term storage. This barrier prevents the ice from absorbing surrounding food odors and protects it from cross-contamination from other freezer contents. Position the ice storage container away from raw meats and poultry to prevent accidental contact with leaking juices.
Even with proper storage, the quality of ice will eventually decline, so practice a rotation schedule. To ensure the freshest taste and texture, replace stored ice every two to three months. For ice makers, periodically emptying the storage bin and thoroughly cleaning the internal components and water lines can prevent the buildup of mold or bacteria.