Aquatics Guide - 2021 - 4

The Model Aquatic
Health Code:
What You Need to Know
By Dewey Case

n 2020, the Council for the Model Aquatic Health Code (CMAHC) began
its triennial process of reviewing and evaluating change requests submitted
in 2019 for the upcoming edition of the Centers for Disease Control and
Prevention's (CDC's) Model Aquatic Health Code (MAHC). This was
a herculean task as 530 individual change requests were submitted. To make
matters more challenging, this review process coincided with the ongoing coronavirus (COVID-19) pandemic, which has impacted people around the world.
CMAHC assembled a dedicated group of aquatic professionals,
representing such sectors as public
health, manufacturing, operations
and design. This group gathered to
review and debate the 530 change
requests prior to October 2020,
when all change requests were presented at CMAHC's triennial Vote
on the Code conference.
Following the conference, a 30day voting window was opened for
CMAHC members to vote on change
requests - the results of which will
be considered by CMAHC's Board
of Directors with recommendations
made to CDC for inclusion in the
fourth edition of the MAHC, to be
released in summer 2021.
This article includes highlights of
the 2020 Vote on the Code results.
While many change requests are minor - such as clarifying terms or creating more consistency among code
sections - others are significant.
It is important to note that as of
this writing, the process is ongoing.

Parks & Recreation

The CMAHC Board of Directors will
convene in early 2021 to make recommendations for CDC's review.

The Use of Cyanuric
Acid and Isocyanurates
Very few things stir up heated discussion like the use of cyanuric acid
(CYA). Whether one supports or is
against the use of CYA, one thing is
true: for many aquatic venues, CYA
and the products that contain CYA
(isocyanurates) are necessary chemical
additions. The addition of this chemical, specifically in outdoor aquatic venues, helps stabilize and shield chlorine
from degradation by the sun.
Since 2016, a CMAHC committee
has studied and debated the use of
CYA. As a result of the committee's
research, a novel model was created to identify risk with varying CYA
levels. The model was highlighted
in an article published in the journal
Water (tinyurl.com/y49e3ld4), while
its findings were presented at various conferences, including the World

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Aquatic Health Conference. Although significant debate surrounding
use of CYAs continues, the research
points to a CYA-to-chlorine ratio that
does not exceed 45:1 as a best practice.
Regarding the CYA change requests for the MAHC, the most significant is the modification to what is
considered an imminent health hazard and grounds for immediate closure. This includes when the CYA-tochlorine ratio exceeds 45:1 and when
the CYA level exceeds 300 parts per
million (ppm), regardless of the ratio.

Harmonization Between the
MAHC and ISPSC
Since its inception in 2018, a committee formed to address differences
in the MAHC and the International Swimming Pool and Spa Code
(ISPSC) has identified some discrepancies between the two codes.
It is important to note that these are
not competing codes. The MAHC is a
model code developed by CDC as a resource for authorities having jurisdiction
(AHJ) to update their existing codes, or
to adopt in whole or in part. Several
AHJs have used the MAHC to update
their existing codes, while many others
use it as a guide for best practices.
The ISPSC is part of the family of
international codes developed by the
International Code Council, which has

http://www.tinyurl.com/y49e3ld4

Aquatics Guide - 2021

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