Look up current-edition MAHC water-quality parameter ranges for pool operators

Steps

1. Identify which MAHC edition (if any) your specific state or local jurisdiction has actually adopted — CDC has published multiple editions (e.g., 3rd edition 2018, 4th edition February 2023, 5th edition December 2024) and adoption timelines vary widely by jurisdiction.
2. Go to CDC's own Model Aquatic Health Code pages (cdc.gov) to pull the code language for whichever edition applies, rather than a secondhand blog or vendor summary.
3. Cross-check the MAHC parameter table against the actual state/local health code in force, since MAHC is a model code — the enforceable numbers are whatever the state or local regulator adopted, which may differ from the latest MAHC edition.
4. Note edition-to-edition changes explicitly (e.g., the CYA operating ceiling and combined chlorine action threshold have been revised between editions) before quoting a specific number to a client or in documentation.
5. When in doubt about which value currently governs a specific facility, contact the local health department directly rather than assuming the newest CDC PDF applies.