Public Pools

CDC Releases the 4th Edition of the Model Aquatic Health Code

Mar 23, 2023 | Rebecca Rainey

The U.S. Centers for Disease Control and Prevention (CDC) has released the 4th edition of the Model Aquatic Health Code (MAHC), found here. First published in 2014, the MAHC is a set of guidelines intended to prevent injury and illness at public aquatic venues, such as pools, hot tubs, and splash pads, and created in a collaborative effort between public health officials and aquatics sector leaders. Developed using the latest science and best practices, these guidelines seek to reduce the leading health risks of aquatic venues, such as swimming-related disease outbreaks, drowning, and pool chemical injuries. Jurisdictions can voluntarily adopt all or parts of the MAHC, and aquatic sector leaders can use the MAHC as guidance even if their jurisdiction has not adopted the code.

The Council for the Model Aquatic Health Code (CMAHC) was established to help the CDC keep up to date with the latest advances in the aquatics sector and update the MAHC accordingly. In addition to language standardization and other formatting changes, key content changes made in the 4th edition of the MAHC include:

  1. Cyanuric acid as a closure item
    Aquatic venues using chlorine stabilizers where the cyanuric acid to DPD-free chlorine concentration ratio exceeds 45:1 are considered imminent health hazards that may necessitate immediate correction or closure. Recognizing cyanuric acid ratio as a closure item can help prevent pathogen transmission.
  2. Lower minimum pH
    The pH of water shall be maintained at 7.0-7.8.
  3. Starting platforms and minimum water depth for new construction
    New construction of starting platforms shall be installed at a minimum water depth of six feet; increasing this minimum depth may help prevent spinal cord injuries.
  4. Maximum vertical clearance
    The maximum vertical clearance at the bottom of an aquatic venue or facility enclosure should not exceed 2 inches above grade on non-solid surfaces (including grass and gravel) and 4 inches above grade on solid surfaces. These maximum vertical clearances may help prevent drowning and increase aquatic venue safety.

Stay tuned for updated inspection forms and other MAHC-related resources at the CDC website here.

Get Involved

NACCHO and CDC support the Model Aquatic Health Code through the MAHC Network, a community of MAHC users, subject matter experts, and those interested in the code. Members will receive code updates and resources, provide input on new resources, and access webinars featuring the code and its users. Visit NACCHO’s MAHC webpage to learn more and join the e-newsletter.


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