16 July 2019

Ice Machines and Legionella

A Growing Problem

Each day people all over the world are exposed to ice. Whether it be from their refrigerator ice machine, their favorite restaurant, during their hospital stay, or on an airplane, people sip on their ice cold beverages or suck on ice chips unaware of the microorganisms that could be sitting dormant within the ice. 

Over the last few years, Legionella, a bacteria that causes Legionnaires’ disease, has become a topic of interest in the water treatment industry. Organizations such as ASHRAE and NSF have created standards which outline the steps for developing water management plans to minimize the risk for legionella growth in building water systems. The Centers for Medicare and Medicaid Services (CMS) followed suit in June 2017 by issuing a memorandum stating that any facility housing patients longer than 24 hours is required to have a water management plan in place. While there are no concrete microbiological standards for ice and ice-related equipment, each of these standards and memos have outlined ice machines as being a critical component that needs control measures developed to minimize the growth of Legionella.

Ice machines can harbor a wide range of microorganisms, which may be present in the ice, ice storage chests, or ice-making machines. They become infected through the potable water used to make ice or from human contact with ice and ice machine surfaces. Scientific literature states that while bacteria is unable to grow in cold conditions, it is able to survive freezing. This allows the microorganisms to become encased in the ice and released as it thaws. Ice machines also provide an environment that promotes bacterial growth due to compressors that warm the incoming water lines to the machine.

Bacterial contamination is a particular concern in healthcare facilities where ice machines are found on almost every floor, including units that serve its most at risk patients. A 2018 study of 5 hospitals and 2 nursing home facilities found 100% of drain pan samples, 52% of ice and/or water chute samples, and 72% of drain-pan grill samples were contaminated with gram negative bacteria. In 2013, 3 cases of Legionnaires’ disease (including one death) were traced to Legionella in ice machines. The source was located after identifying ice chips as the only exposure to water for one of the patients, who presumably aspirated (choked) while sucking on ice to rehydrate.

A majority of hospital ice machine potable water supply lines are filtered with sediment and carbon filters. Sediment filters typically look like woven string. They generally range from 2 microns to 100 microns and serve mainly to remove incoming rust or iron that comes in from the public water supply. Carbon filters are seen to improve the taste of water by removing the public water supplies disinfectant, which in most cases is chlorine. This leaves the ice machine supply water more susceptible to bacterial contamination due to minimal, if any, disinfectant remaining after the filter. When these carbon filters become saturated with organic contaminants or sit stagnant for more than a few days, they can also become a food source for bacteria.

Ice machines have become a critical control point in a hospital’s water management plan to control Legionella. Some facilities have moved to Point-of-Use (POU) filters instead of, or in addition-to, sediment and carbon filters. These POU filters employ hollow-fiber-membrane or surface filter technologies to remove Legionella and other pathogenic bacteria from the water used to make the ice. These filters are able to remove particulates less than 0.2 microns in size, and are ASTM rated and FDA approved for bacterial retention.

Whatever your filtration needs, Chem-Aqua has the expertise and resources to handle your systems specific requirements. Contact us today to learn more!

Written by: Caroline Hettermann

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