Debunking Myths About the MAHC

The Model Aquatic Health Code (MAHC) is a collaborative effort of public health, academia, and the aquatics industry, working to protect individuals, families, and communities from preventable waterborne diseases and injuries through evidence-based guidance. NSPF understands that industry professionals need the most accurate information on the MAHC when discussing issues with colleagues or making important decisions. With specific questions about the MAHC, professionals can be on top of the game with the latest and most accurate information from the MAHC technical experts by contacting the CDC ( or the CMAHC (  

On August 14, 2017, the Arizona Department of Environmental Quality held a hearing on proposed adoption of the MAHC. Industry leaders including NSPF and the CDC testified against misinformation presented at the hearing. Here are CDC responses to myths about the MAHC: 

Will general contractors and developers be able to build pools?

The MAHC is silent on who can build pools, but it does state that no person shall begin to construct a new aquatic facility or shall substantially alter an existing aquatic facility without first having the construction plans detailing the construction or substantial alteration submitted to and approved by the authority having jurisdiction.

Must all plans be stamped by an architect or engineer?

The MAHC does not specifically require an architect or engineer, rather it refers/defers to the state or local laws for the appropriate design professional.

Will the hydraulic requirements for drains and skimmers require pipe sizes to be at 225% of the designed system flow, since the main drain would have to be at 100% and the skimmers at 125%? 

The gutter system shall be designed to allow continuous removal of water from the pool’s upper surface at a rate of at least 125% of the approved total recirculation flow rate chosen by the designer. This is to provide for adequate skimming during surge conditions by providing sufficient capacity in the gutter system to handle the water displaced by bathers (static surge) and activities (dynamic surge) without flooding the gutters making them ineffective. When used, the skimmer system shall be designed to handle up to 100% of the total recirculation flow rate chosen by the designer.

Would the hydraulic requirements of the MAHC significantly increase the number of skimmers required?

Where skimmers are used, at least one surface skimmer shall be provided for each 500 square feet (46 m2) of surface area or fraction thereof. This is consistent with ANSI/NSPI and the 2015 ISPSC as well as many existing health codes and with the NSF recommendations for installation and operation for public swimming pools. 

With the MAHC’s hydraulic requirements for drains and skimmers, will the cost of piping increase significantly as the diameter increases?

While there is a cost increase with pipe size diameter, the additional capital cost for PVC pipe is more than compensated for in operational cost and energy savings achieved by the larger pipe size.

Will the faster turnover requirements, especially for lazy rivers, significantly increase the required pump sizes, which will increase the required filter and plumbing sizes, all of which unnecessarily increase construction cost and energy consumption?

The turnover rate requirements address what is necessary to adequately remove suspended matter with the filters and maintaining uniform chlorine residuals. The rates specified in the MAHC are consistent with existing requirements in many state health jurisdictions. Potentially increased sizing of equipment such as pumps, filters, piping necessary to meet and maintain water quality and protect public health are not considered “unnecessary” costs.

Will automated chemical systems be required for all public and semi-public pools within 1 year? 

  • Aren’t these systems very expensive to install, complicated to maintain, and prone to error if not properly maintained and calibrated? 
  • Will legislation and rules like this make it harder for businesses to work in the state and increase taxes?
  • Will this requirement will push many independent business people out of the business of maintaining small semi-public pools?  
  • Will the additional costs likely result in some HOA's and apartment/condo complexes raising their rents and HOA fees since they likely won't have the funds in their budgets to cover these expenses? 
  • While this is not a "tax," is it a financial burden on the general public as a result of government mandates?

Automated controllers are required after one year in all facilities. Disease outbreak investigations and inspection reports have shown the need for all aquatic venues to have automated chemical systems. While it is agreed that they must be maintained as all aquatic systems and require maintenance, hand-feeding chemicals is more prone to error. Automated control of chemical levels is likely to reduce the use of chemicals by avoiding the dramatic swings in chemical levels typical of hand-feeding. Automation can also reduce the periods of poor water quality that put swimmer health at risk. As discussed in the MAHC annex: 

“Constant and regular monitoring of key water quality parameters such as the disinfectant level and pH are critical to prevent recreational water illness and outbreaks. automated controllers are more reliable as a monitoring device than personnel and hand feeding chemical. Automated chemical controllers are therefore required for use on every aquatic venue with a time of one year built in for facilities to become compliant after adoption of this requirement. The use of automated controllers does not negate the requirements for regular water testing. Automated units require verification of proper function and the probes do fail or slip out of calibration. This can only be detected by monitoring the water quality.” 

Numerous reports by the CDC show that outbreaks of recreational water illnesses associated with chlorine sensitive pathogens occur at public treated recreational water facilities each year. Because these organisms are readily killed or inactivated by chlorine, the cause can be attributed to inadequate disinfection. Additional reports show that hotels and motels and apartment complexes have the most cited water quality violations. The installation and proper maintenance of automated controllers are important in maintaining proper water quality to protect the health of the pool users. Automation of these processes is critical to maintaining water quality and is underscored by detection of multiple outbreaks where no automation was in place and human error led to inadequate chlorination and spread of disease.

Due to the automated chemical systems, will there be a need for a significant increase in the number of inspectors to make sure that these pools are in compliance, and will these inspectors need training in the various automation systems?

The responsibility for operating a pool in compliance with requirements rests with the owner or operator. The claimed need for additional health inspectors based on revised requirements does not make sense. Inspectors’ roles regarding compliance checks aren’t changed by revised content. Checking for an operational controller adds little time to an inspection.

Isn’t the MAHC created by a federal government agency, and not through a consensus process like the ICC and ANSI process used for the ISPSC, leaving it vulnerable to a select few people with their own agendas and without the vetting process that the other standards go through?

The MAHC was developed using the best available science and best practices, and a national, multi-partner, inclusive, consensus process involving over 140 public health and aquatic sector experts. As part of creating the MAHC, CDC held two 60-day public comment periods, received 4,407 comments, and accepted 73% of comments that pertained to changes. The availability of the MAHC provides state and local agencies with the best available guidance for protecting public health to be used to create or update swimming pool codes, while conserving valuable time and resources previously used to write or update code language; use of the MAHC is voluntary since it is guidance and is intended to enable more efficient upkeep of existing state and local regulations. After seven years of multi-stakeholder collaboration, CDC released the 2014 Model Aquatic Health Code (1st Edition). The MAHC update process uses the consensus process and public health and aquatics sector partnership created by the non-profit Council for the MAHC (CMAHC) to develop recommendations for MAHC updates. Only three years after its creation, the CMAHC has more than 700 members, with a majority from the aquatics sector. The CMAHC process successfully resulted in CDC release of the 2016 MAHC (2nd Edition) only 2 years after the 1st edition. 

Use of the MAHC as a guide for pool programs has been endorsed by:

Membership in the Council for the Model Aquatic Health Code (CMAHC) earns members active participation in the process of MAHC updates, consistent with the MAHC motto, “driven by your expertise.” Every two years, members are invited to submit, review, and vote on Change Requests to the MAHC that will be sent to CDC. Approved change requests are compiled and released in subsequent editions of the MAHC. NSPF invites individuals and organizations to join the CMAHC and attend the CMAHC Vote on the Code Biennial Conference October 17-18, 2017, in Denver, Colorado.

During the process of adoption of the MAHC, questions will arise demanding accurate answers. The CDC and the Council for the Model Aquatic Health Code (CMAHC) remain the source for validating facts and application of the MAHC. To join the CMAHC or get more information, click here.


Busting the Myths
Council for Model Aquatic Health Code
Model Aquatic Health Code