AWWA C652-2019, or ANSI/AWWA C652, describes methods of disinfecting water storage facilities and tanks.
Every person needs readily available potable water, and, as population increases, a greater supply of the transparent life force is needed. Facilities that maintain such a steady supply of water are no new feat, certainly not in the United States. In fact, water storage systems inside the country predate the nation itself—the Hohokam, who occupied modern-day Arizona as early as the first century A.D. and are famed for their extensive irrigation canals, maintained water storage reservoirs.
Today, from water towers supporting small bucolic towns to the 19 reservoirs from which 1.2 billion gallons of high-quality drinking water travels 125 miles to New York City, the United States has its share of facilities for storing water. Together, they play an integral role in supporting modern civilization, and must maintain an environment suitable for such an endeavor. As noted in AWWA C652-2019, water storage facilities should be disinfected before they are placed into service.
Regulation of Drinking Water in the United States
In the United States, authority to regulate products for use in, or in contact with, drinking water rests with individual states, and local agencies may choose to impose more-stringent requirements. To evaluate the health effects of products and drinking water additives, the authority having jurisdiction can turn to specific policies of the state or local agency as reference, as well as two standards developed by NSF International: NSF/ANSI/CAN 60-2019: Drinking Water Treatment Chemicals – Health Effects and NSF/ANSI/CAN 61-2019: Drinking Water System Components – Health Effects.
Numerous other standards support the delivery of clean water. Back in 1985, the US Environmental Protection Agency (EPA) entered into a cooperative agreement with a consortium led by NSF International (NSF) to develop voluntary third-party consensus standards and a certification program for direct and indirect drinking water additives. The American Water Works Association (AWWA) later joined this consortium.
The American National Standard for the disinfection of water storage facilities emerged around this time. 1980 saw the standard’s first approval under its initial designation ANSI/AWWA D105. A redesignation and several revisions culminated in AWWA C652-2019.
AWWA C652-2019
Useful as a guide in preparing water-storage facilities for disinfection procedures following inspection or maintenance and as a reference in specifications for the disinfection of water storage facilities, AWWA C652-2019 outlines a variety of stipulations.
This includes the preparation of water-storage facilities, application of chlorine, and sampling and testing for the presence of coliform bacteria, chlorine residual, and acceptable aesthetic water quality. The standard also features disinfection procedures for underwater inspection and/or cleaning of potable-water-storage facilities—that said, it does not describe the technical aspects of underwater inspection and/or cleaning.
This standard describes only the use of liquid chlorine (gas), sodium hypochlorite solutions, and calcium hypochlorite. In addition to new storage facilities, the standard can be used to aid disinfection processes for water storage facilities have been entered for construction or inspection purposes, or continue to show the presence of coliform bacteria during normal operation.
Changes to AWWA C652-2019
Further fortifying the standard’s success in meeting its purpose, additions made to AWWA C652-2019 from the 2011 edition of the same standard address concerns in achieving chlorine levels in chloraminated systems.
Beyond this, clarification was added to AWWA C652-2019 regarding its use with public water system tanks and not for tanks used within premise plumbing systems. The standard also provides clarification on when disinfection, sampling, or both may be required, and it now acknowledges that remotely operated vehicles (ROVs) may be used for tank inspections.
Furthermore, previous Appendix C, “Disposal of Highly Chlorinated Water,” was deleted. For dechlorination procedures, users should instead refer to AWWA C655-18: Field Dechlorination.
Definitions were also added for chloramine, inspection firm, liquid chlorine (gas), reclaimed water, and wastewater.
AWWA C652-2019: Disinfection Of Water Storage Facilities is available on the ANSI Webstore.
