What Is the Model Aquatic Health Code?
The MAHC is guidance the CDC publishes for public pools, hot tubs, and splash pads. It is voluntary. Each state, county, or city decides whether to adopt it, in whole or in part, when it writes or updates its own pool code, and adoption timing varies widely. Some jurisdictions have adopted large parts of it. Many still enforce codes of their own. What you are legally held to is your state and local code.
The current version is the 5th edition, which the CDC posted in December 2024. There is no 2025 edition.
What Changed in the 2024 MAHC
The CDC's summary of the 5th edition lists the following changes.
1. Chlorine and Cyanuric Acid Upper Limits
The upper operating range for chlorine products now follows the product manufacturer's label instructions, in line with EPA pesticide labeling rules. The cyanuric acid requirements were also modified, and a CYA level of 300 ppm or higher now calls for immediate remediation.
2. New Immediate Closure Conditions
Chapter 6 adds three conditions that require immediate closure, including free chlorine above 10 ppm while bathers are present. The other two involve interlock control failures and unauthorized access to chemical storage.
3. Updated Diarrheal Incident Response
The diarrheal-stool contamination response now allows dilution credits when you lower cyanuric acid by draining and refilling. Our fecal incident response guide walks through the full CDC procedure.
4. Lifeguard Staffing
The 5th edition requires two qualified lifeguards to be present at facilities with a single-zone surveillance area.
5. Design and Venue Changes
Portable slides are prohibited. A clock must be visible to all spa bathers. Single-pass splash pads are now defined and covered as interactive water play venues, and artificial swimming lagoons were added as a special venue with design, construction, and operating standards.
What This Means for Your Facility
None of these changes apply to your pool until your state or local health department adopts them. Call your health department and ask which code it enforces and whether it plans to adopt any part of the 2024 MAHC.
Some of these are good practice anyway. Keep chlorine within the range on your product label, test cyanuric acid on a regular schedule if you use it, make sure every staff member knows your closure conditions and your fecal incident procedure, and keep clear, dated records of every test and corrective action.
If your code requires a certified operator, the PHTA CPO course covers the water chemistry, safety, and record-keeping the MAHC is built around.
Frequently Asked Questions
Q: Is there a 2025 Model Aquatic Health Code?
A: No. The current edition is the 5th edition, posted by the CDC in December 2024. Check the CDC's MAHC page for any newer edition.
Q: Will my state enforce the 2024 MAHC?
A: Only if it adopts it. The MAHC is voluntary guidance, and each state or local health department sets its own schedule, adopts only parts, or keeps its own code. Ask your health department which code applies to your facility.
Q: Does my CPO need to be updated for the 2024 MAHC?
A: No. Your PHTA CPO certificate stays valid for its full five years regardless of MAHC updates. When you recertify, you will study current material.
Want to stay ahead of compliance changes? CPO PRO runs PHTA CPO test days on Zoom every Tuesday and Saturday. Book your class today.
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