The second edition of the Model Aquatic Health Code has been released, marking changes from minor to substantial, and raising at least one major question that will be explored for the next revision.

This marks the first revision of the landmark federal model code for commercial aquatics facilities. For this code, a committee called the Council for the Model Aquatic Health Code (CMAHC) generates and evaluates dozens of change requests and determines which ones it will recommend to the Centers for Disease Control and Prevention, the agency charged with writing and administering the language. The CDC then chooses which change requests it approves and changes the code based on that. (While the MAHC is federally based, it is a model code, meaning it does not take effect unless a state or municipal entity chooses to adopt it.)

The MAHC was written as a comprehensive code, covering the gamut from design to water treatment to lifeguard training. The changes showed this diversity.

Some alterations increased the amount of information that must be explored and provided as part of the design process, to ensure that a facility is built to its stated purpose. For instance, a zoning plan for positioning lifeguards must be included in the plans, showing features and design characteristics that could affect the ability to monitor users. This is meant to avoid situations where operators plan to use a certain number of lifeguards , but then find they need more after construction. In such cases, operators sometimes stick to the lower staffing plans, causing a risk to users, said CMAHC Executive Director Douglas Sackett.

“That’s just an example of what can go wrong and what has gone wrong in the past,” he said. “So what we’re asking for now in the design is to lay out those zones, so they have to consult with a water-safety expert or the owner … so you know upfront what you’re looking at and whether there are problems, and then everybody’s on board instead of having quite a rude awakening…”

Along a similar line, designers must consult with their clients to determine in detail how the facilities will be used and what temperature the water will be to accurately estimate the needs of ventilation systems. Plans must indicate air handling needs and information such as whether there will be moving water like waterfeatures and spa jets, and what the typical temperatures will be. “If they design it for one use, but then it’s built and operated differently, the air handling system may not be able to handle it, and the humidity could be problematic,” Sackett said.

The new version of the MAHC also raises the minimum height for self-latching gate mechanisms from 3-1/2 to 4-12 feet to move them out of the reach of young children. It also names the parameters that must be met for materials to be considered slip resistant, since a test has recently become available to help determine this property.

One change regarding electrical safety could have a significant impact among older commercial pools in areas where the MAHC is adopted: All underwater lighting would have to be protected by a ground fault circuit interrupter, unless they qualify as low-voltage lamps. While the National Electrical Code has long required this for new construction and some renovations, the MAHC change would require it on any existing pool as well.

But the CDC also turned down a significant change request - one involving cyanuric acid levels in pools. CYA is a stabilizer, meaning it protects chlorine from ultraviolet degradation. But it also has a limiting effect on the amount of chlorine that's available at any given time. The CMAHC proposed lowering levels from 100 to 20 parts per million, in the hopes of freeing up more available chlorine to combat pathogens. The request came as a result of a study suggesting that more than 15 or 20 ppm could hamper efforts to manage outbreaks of cryptosporidium. But because the study did not address normal operating conditions, the CDC vetoed the change. The CMAHC is currently compiling data showing the impact of higher CYA levels on the ability to address everyday pathogens and may propose this again in 2017.