Standards Matter
August 10, 2023

Addressing the Unseen Safety Risks of Water Coolers with UL 399


Woman's hand filling water glass at cooler.

Why It Matters

One of the most often overlooked, yet most frequently used pieces of equipment in any workspace is the water cooler. Sure, the water cooler is always there and ready to dispense the refreshing nectar of life when it’s needed, and rarely is a thought ever given to the potential havoc an unsafe water cooler can cause. Improperly installed and poorly constructed water coolers can cause fires, leak dangerous coolants, and even cause illness. In January 2023, a water cooler imploded in Chicago, resulting in property damage due to the building’s sprinkler system response. Luckily, nobody was injured. 

What We’re Doing 

UL Standards & Engagement published UL 399, the Standard for Safety Drinking Water Coolers, which covers self-contained water coolers employing a hermetic refrigerant motor compressor or thermoelectric water chilling system. In other words, this Standard covers construction, performance, and testing requirements for coolers dispensing both hot and cold water.  

One of these requirements covers electrical protection due to the necessary louvered design of the cooler. These louvers are required for proper airflow to the internal components; however, they also provide a potential entry point for conductive materials. According to UL 399, all louvers and knockout points must be tested with a ¾-inch rod and must not allow the rod to contact any uninsulated high-voltage live wires or film coated wires when applied to the opening with a force of five pounds. In environments where equipment and people are moving fast, this is an essential measure to help protect fuses, equipment, and personnel. 

Another section of this Standard focuses on the water contained in the cooler. It is a widely known fact that water and electrical current create a dangerous electrical hazard, which can appear like nothing more than a puddle that needs a simple mop and bucket to mitigate. To help protect cleaning personnel and passersby from the risk of electrical shock and more stemming from a water leak, UL 399 specifies construction requirements for the cooler to move water away from the electrical components. The Standard’s requirements for the construction of drip pans and drain basins help ensure that the water is kept away from electrical current during normal operations, such as replacing the water bottle. To conform to UL 399, water coolers must pass this leak test. 

UL 399 also considers the potential environmental impact that water coolers can pose due to the use of coolants and provides requirements to mitigate the risk of refrigerant leaks. In addition to being flammable, refrigerants cooling the water can also pose health risks if users inhaled or come into contact with them. Due to these risks, the Standard’s requirements for the construction of refrigerant tubing and joints within the water coolers state that all water cooler fittings must be protected or enclosed without the possibility of being grasped from the outside of the unit. Further, all joints in the construction of the tubing must be brazed or welded, and quick-connect fittings cannot be used. This is all to help ensure that the frequent problem areas for coolant leaks are properly reinforced to manage the stresses of daily use. 

How You Can Help 

Our standards are developed through a consensus-based process, which integrates scientific and testing expertise with input from our Technical Committee (TC) members and stakeholders. TC members represent a variety of interests, including industry, academia, government, retail, and manufacturing. If you are involved in the design, manufacture, sale, installation, or maintenance of water coolers, and you would like to help improve safety in your industry, please take a moment to learn how you can get involved.