By Paul K. Overbeck

In late 1993, the Water Quality Association (WQA) created the Ozone Task Force under the Science Advisory Committee at the urging of its membership who were starting to see ozone as a valuable process step to meet residential, commercial and municipal treatment goals. At the same time, the International Ozone Association (IOA) was supporting the U.S. Environmental Protection Agency (USEPA) in evaluating the benefits of ozone in municipal drinking water treatment. Part of this evaluation included identifying municipal ozone installations throughout the United States.

A cooperative approach
Many of the new WQA Ozone Task Force members were and are also IOA members. This created a naturally synergistic team approach to meeting the objectives of both associations. The resulting WQA Ozone Task Force’s charter was established to include:

  1. Development of ozone generator product performance guidelines and standards,
  2. Creation of educational materials for the use of ozone in point-of-entry and point-of-use (POU/POE) and small system applications, and
  3. Legislative support on the use of ozone in small systems.

The following update of WQA’s Ozone Task Force activities is provided as we enter an era where water treatment at POE and POU, small and large municipal, commercial and industrial levels will be more important to mankind than ever before.

Guidelines and standards
The Ozone Task Force produced, “A Testing Methodology Guideline for Performance Measurement of Ozone Generators” which was published March 1996.1 Since its introduction, a number of ozone generator manufacturers have voluntarily complied with the guideline for product testing and have used the data in their product brochures and technical support materials for their dealer distribution system.

The task force believed it needed to go further than this voluntary guideline and is now close to finalizing a “standard” that can be used for third party product performance certification. It is of the opinion that product certification under an approved standard will help dealers confidently employ ozone to meet specific customer needs. This certification standard can be used in WQA Gold Seal certification or NSF certification programs similar to those currently used for other products offered through WQA members.

The ozone generator standard will be reviewed during the WQA Annual Convention this month in Long Beach, Calif.

Educational material
The Ozone Task Force published Ozone for Point-of-Use, Point-of-Entry, and Small Water System Water Treatment Applications—A Reference Manual2 at the 1998 WQA convention in Fort Lauderdale. The book was positively received by WQA members and due to demand was reprinted in 1999.

Feedback on the manual and from initial installation surveys helped task force members identify the need for greater support material on the use of ozone in groundwater treatment. Ozone is typically used in this area for oxidation and not primary disinfection. Iron, manganese, sulfide ions (S2-/H2S), and color, taste and odor reduction are the most common applications in groundwater treatment.

The USEPA lists approximately 171,000 water systems in the United States.3 The majority of these (158,000) utilize groundwater as their source water. These water systems are a combination of Community Water Systems (CWS), Non-Community Transient (NCT) and Non-Community Non-Transient (NCNT) operations. Groundwater systems are made up of 44,000 CWSs (28 percent), 94,000 NCTs (60 percent), and 20,000 NCNTs (12 percent)—with less than 50 percent of all groundwater systems practicing disinfection.

It was determined use of ozone for these applications wasn’t as well understood as that of other oxidizing substances—such as chlorine (Cl2) and potassium permanganate (KMnO4). Ozone contacting, applied dosage, reaction rates, detention time, filtration and material compatibility requirements mandate more definition to allow greater dealer application confidence.

A subcommittee was formed during the 1999 WQA Convention in Fort Worth, Texas, to address this need. Members of the subcommittee include ozone generator manufacturers, dealers with hands on experience using ozone in groundwater applications and consultants. A resulting “White Paper” is scheduled for presentation and publication at the 2000 Long Beach convention.

Legislative support
The year 1999 marked the 25th anniversary of the U.S. enactment of the Safe Drinking Water Act (SDWA). The original SDWA charged the USEPA to develop and promulgate a number of regulatory initiatives. Subsequent SDWA amendments (1986 and 1996) have carried additional regulatory mandates to the USEPA, many of which encourage the use of ozone, if only indirectly.

The National Primary Drinking Water Rules (NPDWRs) and the establishment of maximum contaminant levels (MCLs) and treatment technique (TT) requirements for specific substances in drinking water have also driven a revolution in treatment technology development, application and analysis.

In 1996, Congress, in its SDWA reauthorization, directed the USEPA to develop regulations that would be applicable to the needs of small communities as well as large urban populations. Congress identified that most small municipal systems treating less than 1 million gallons per day (3.8 megaliter/day)—defined as plants that serve less than 10,000 persons—have particular challenges due to their size, technical and financial abilities that required special consideration. USEPA further subcategorizes water plants into those serving 25-to-500, 501-to-3,300 and 3,301-to-10,000 persons to better define financial, operation and maintenance capabilities. Previous rules development focused on large systems.

Small drinking water systems are now affected by the December 1998 Disinfectant/Disinfection By-Products (D/DBP) Rule,4 which became effective Feb. 16, 1999. They’ll be equally affected by the future enactment of the Long Term 1 Enhanced Surface Water Treatment Rule5 (LT1ESWTR) addressing Cryptosporidium and the Ground Water Rule (formerly the Ground Water Treatment Rule, or GWTR).

Ozone was included as a compliance technology in the USEPA’s August 1997 list of compliance technologies for the Surface Water Treatment Rule (SWTR)6 and in the August 1998 list of compliance technologies for all the other pre-1996 NPDWRs.7 An installation survey conducted by members of the Ozone Task Force and the IOA in 1997 was used to explain to the USEPA how ozone is being used in the United States on small and large municipal drinking water systems.

Ongoing survey details on ozone installations including size, water source, treatment objectives, performance, capital and operating cost will assist the USEPA and state regulators in developing community support information on treatment techniques to meet current and future regulations.

The ongoing efforts of the Ozone Task Force are producing valuable support to WQA membership and government agencies. Additional support is needed to gather greater detail on the use of ozone in our industry. Development of an ozone generator testing protocol for effective third party testing of such equipment is also an integral part of promoting effective use of the technology in small system and other applications.  Additional points to keep in mind:

  • Regulatory activities are driving change in the drinking water industry to provide added protection to the public health.
  • Ozone has been identified and listed by the USEPA as an affordable compliance technology for surface water disinfection and specific oxidation applications.
  • The Water Quality Association and the International Ozone Association will work together to gather additional installation and ozone operating plant survey data to support USEPA regulatory development.


  1. Water Quality Association, A Testing Methodology Guideline for Performance Measurement of Ozone Generators, J.F. Harrison and P. Blazek, editors, WQA, Lisle, Ill., March 1996.
  2. Water Quality Association, Ozone for Point-of-Use, Point-of-Entry, and Small Water System Water Treatment Applications—A Reference Manual, J.F. Harrison and P. Blazek, editors, WQA, Lisle, Ill., 1997.
  3. USEPA, “National Primary Drinking Water Regulations: Ground Water Treatment Rule; Notice of Data Availability; Proposed Rule,” 1996.
  4. USEPA, “National Primary Drinking Water Regulations: Disinfectants and Disinfection Byproducts; Final Rule,” Federal Register, 63(99): 24169390-24169476, 1996.
  5. USEPA, “National Primary Drinking Water Regulations: Interim Enhanced Surface Water Treatment; Final Rule,” Federal Register 63(98): 24169478-24169521, 1996.
  6. USEPA, “Small Systems Compliance Technology List for the Surface Water Treatment Rule,” Document # USEPA 815-R-97-002, August 1997.
  7. USEPA, “Small Systems Compliance Technology List for the Surface Water Treatment Rule and Total Coliform Rule,” Document # USEPA 815-R-98-001, September 1998.
  8. USEPA, “Small Systems Compliance Technology List for the Non-Microbial Contaminants Regulated Before 1996,” Document # USEPA 815-R-98-002, September 1998.
  9. Rice, R.G., P.K. Overbeck and K. Larsen, “Ozone Treatment of Small Water Systems,” International Ozone Association Conference proceedings, October 1998.

About the author
Paul Overbeck, president of Phoenix’s GDT Water Process Corp., is a member of the WC&P Technical Review Committee, chairman of the International Ozone Association’s Small Systems Committee and past chairman of the Water Quality Association’s Ozone Task Force. He’s also a member of the AWWA, WEF, IBWA and IAWQ. He can be reached at (623) 587-8858, (623) 587-1511 or email:


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