Identify the current CDC Model Aquatic Health Code (MAHC) edition and determine how it applies given your state's adoption status

Steps

1. Confirm the current MAHC is the 5th edition, with the Code released December 16, 2024 and the accompanying Annex released the same date and revised February 4, 2025 — check cdc.gov's MAHC 'current edition' page for any newer release before relying on this
2. Understand the MAHC is voluntary model guidance, not federal law — it only has legal force where a state or local jurisdiction has formally adopted it, in whole, in part, or by reference
3. Check your specific state/local health department code to see which MAHC edition, if any, it has adopted, since many jurisdictions lag behind the current CDC edition or adopt only portions
4. Where the local code is silent or ambiguous, use the current MAHC as the recommended best-practice reference, but defer to the codified local requirement wherever the two conflict
5. Note edition-specific changes relevant to service work (e.g., the 5th edition's 300 ppm CYA immediate-remediation threshold and updated splash pad/lifeguard-zone provisions) when advising facility operators