Disinfection Regulations

Disinfection is required under two Safe Drinking Water Act regulations, the Surface Water Treatment Rule of 1989, as amended, and the Ground Water Rule of 2006.

EPA developed these rules and an extensive collection of guidance and implemetation resources over several years under what was known as the microbial and disinfectants/disinfection byproducts (D/DBP) rulemakings.

As water systems across the United States have begun to implement these regulations, the selection of disinfection methods has become an increasingly challenging issue, compounded by emerging concerns about the security of water treatment systems.

Selecting a disinfection method, whether it is chlorine gas or a new technology such as ultraviolet light, is central to the design and operation of drinking water, wastewater and reuse systems. And the considerations that drive disinfectant selection are local, system-specific and deeply intertwined.

Fully considering the pros and cons of multiple drinking water treatment options is important for utility decision-making, and this is especially true of disinfectant selection. When making such decisions, utilities must balance community and personnel safety concerns with the appropriate level of disinfection to ensure drinking water safety.

As disinfectant selection becomes more complex, the importance of undertaking a transparent, well-informed and goal-driven selection process becomes more critical.

Rule review under way


Most recently, EPA has begun reviewing the 2005 Long-Term 2 Enhanced Surface Treatment Rule under the SDWA's requirement to review rules every six years. The agency is assessing and analyzing information regarding occurrence, treatment, analytical methods, health effects and risk from all relevant waterborne pathogens to evaluate whether there are new or additional ways to manage risk while assuring equivalent or improved protection.

Through 2012, EPA has held three public meetings on the rule review, and AWWA has been at the table for all of them. The agency plans to complete this review no later than 2016. Look for more details here in the near future.

regulatory details and resources

Surface Water Treatment Rules


EPA regulations


Surface Water TreaTment Rule

The original SWTR published in 1989 applies to all public water systems that use surface water or ground water under direct influence (GWUDI). It establishes a treatment technique that requires filtration unless certain criteria are met and it sets minimum disinfection requirements for Giardia lamblia and viruses.

Interim Enhanced SWTR and Stage 1 disinfectants/disinfection byproducts rule

The Interim Enhanced SWTR of December 1998 applies to public water systems that use surface water or groundwater under the direct influence of surface water (GWUDI) and serve at least 10,000 people. It requires states to conduct sanitary surveys for all surface water and GWUDI systems, including those that serve fewer than 10,000 people. The IESWTR amended the SWTR to strengthen microbial protection, including provisions specifically to address Cryptosporidium.

It was promulgated along with the Stage 1 Disinfectants/Disinfection Byproducts Rule, which reduced exposure to DBPs for customers of community water systems and non-transient noncommunity systems, including those serving fewer than 10,000 people, that add a disinfectant to the drinking water during any part of the treatment process.

Long-term 1 Enhanced SWTR

The Long-Term 1 ESWTR of January 2002 is a companion rule to the IESWTR and Stage 1 D/DBPR, providing parallel provisions for systems that serve fewer than 10,000 persons.

Long-term 2 ESWTR and stage 2 d/dbpr

The Long-Term 2 ESWTR of December 2005 applies to all public water systems that use surface water or GWUDI. In order to comply with the rule, water treatment plants that employ filtration must monitor their influent water and determine what Cryptosporidium occurrence “bin” the water treatment plant falls in. If classified in a higher bins, the plant must provide additional water treatment to further reduce Cryptosporidium levels by 1.0 - 2.5 log, depending on the bin.

It was promulgated along with the Stage 2 D/DBPR, which builds upon the Stage 1 D/DBPR by tightening compliance monitoring requirements for two groups of DBPs: total trihalomethanes (TTHM) and five haloacetic acids (HAA5). The rule targets systems with the greatest risk.

Most recently, EPA has begun reviewing the Long-Term 2 ESWTR under the SDWA's requirement to review rules every six years. The agency is assessing and analyzing information regarding occurrence, treatment, analytical methods, health effects and risk from all relevant waterborne pathogens to evaluate whether there are new or additional ways to manage risk while assuring equivalent or improved protection.

Through 2012, EPA has held three public meetings on the rule review, and AWWA has been at the table for all of them. The agency plans to complete this review no later than 2016. Look for more details here in the near future.

AWWA activities

AWWA was actively involved as a stakeholder in all phases of the development of these regulations, including providing the following formal comments that helped to formulate the final rules and companion guidance.

 



Ground Water Rule


The Ground Water Rule of October 2006 aims to provide increased protection against microbial pathogens in public water systems that use groundwater sources, especially those susceptible to fecal contamination.

It applies to public water systems that serve groundwater and any system that mixes surface and groundwater if the groundwater is added directly to the distribution system and provided to consumers without treatment.

AWWA Activities


AWWA Comments on GWR Triggered and Representative Source Water (PDF)
AWWA Comments on GWR notice of data (PDF)
AWWA Comments on GWR CT and Profiling/Benchmarking Calculators (PDF)
AWWA Comments on GWR Corrective Actions Guidance (PDF)
AWWA Comments on GWR Implementation Guidance (PDF)

Canadian Guidelines


Drinking Water Guidelines from Health Canada assert that, "Barring system specific exemptions, all public water systems, regardless of source water type, should be disinfected to produce microbiologically safe water and should maintain a disinfectant residual throughout the system at all times."

Treatment guidelines have been established for protozoa and enteric viruses as well as monitoring guidelines regarding occurrence of E. coli, total coliforms, heterotrophic plate count and current and emerging microbial contaminants of concern.

In addition, Health Canada has established a guideline for chlorine in drinking water.

Selecting disinfectants


One resource that can inform disinfectant selection is AWWA's guide for drinking water and wastewater systems titled, Selecting Disinfectants in a Security Conscious Environment.

This guide, published in 2009, describes a step-by-step process to evaluate disinfection options that meets the unique needs of each water, wastewater and reuse system. Available in the AWWA Store, the product builds on existing water sector engineering practices, manuals of practice, costing tools and public communication techniques to:

  • address federal and local statutory and regulatory disinfection objectives;
  • reflect local circumstances;
  • compare disinfection options consistently;
  • consider operational, process and supply-chain reliability as well as environmental, operator and community safety considerations;
  • provide transparency in the decision-making process; and
  • incorporate appropriate risk communication within the decision-making process and the community.

5-Step Process

The guide details a 5-step process for selecting disinfectants:

  1. Assess Current Situation. Identify existing and future disinfection requirements and regulations and the ability of the existing disinfection process to meet them. Review past water quality and security assessments and recommendations and determine which recommendations have been or are planned to be implemented. Use the information gathered to establish system disinfection goals and objectives.
  2. Identify Options. Use a screening process to determine which disinfection options are feasible to carry forward for detailed evaluation.
  3. Evaluate Options. Evaluate each disinfection option identified as feasible in Step 2 by defining and then comparing and contrasting the attributes, costs, advantages and disadvantages of each option. This evaluation can reflect on design considerations such as reducing the quantity of hazardous substances stored on-site; the reliability and efficiency of potential disinfectant system options; and simplifying treatment processes where possible.
  4. Select Option. Use the results of the evaluation along with decision-making tools to select the preferred disinfection method.
  5. Implement Selected Option. Design, install, construct and start up the facilities and equipment required to implement the preferred disinfection method.

TOOLS

This resource also illustrates the use of two such tools: multi-attribute utility analysis (MAUA), and expanded social cost effectiveness analysis (ESCEA). CH2M Hill and Stratus Consulting prepared the following two spreadsheet tools that users can adapt to their own circumstances.

Tools

Hypochlorite Assessment Model

This predictive modeling tool, available exclusively to AWWA utility members, provides guidance on the expected levels of perchlorate and chlorate in stored bulk hypochlorite solutions.

AWWA developed this resource based on the findings of a report titled, Hypochlorite - An Assessment of Factors that Influence the Formation of Perchlorate and Other Contaminants (PDF, 1.7MB). Stanford et al also addressed the foundations of this tool in the June 2011 issue of Journal - American Water Works Association. That article, titled "Perchlorate, Bromate, and Chlorate in Hypochlorite Solutions: Guidelines for Utilities" is available for download (free to AWWA Members) in the AWWA Store.

Learn more about and access the tool.

Risk Communication Tools

Risk communication for a specific activity such as disinfectant selection is most effective if coordinated within a water system’s existing public communication program. Building a risk communication plan for disinfectant selection that is aligned with the system’s other ongoing stakeholder communication activities builds credibility and improves effectiveness.

  • AWWA Public Communications Toolkit provides several useful references and tips for strategic communication planning, risk communication and stakeholder outreach.
  • Message Mapping is illustrated in Effective Risk and Crisis Communication During Water Security Emergencies (EPA/600/R-07/027). This preparatory tool is a useful approach to improving communication effectiveness. 
  • Public Involvement: Making it Work. This Water Research Foundation report provides a proven process for developing project-specific public involvement programs, integrating them into a utility's decision-making process, and sustaining them for the project duration. It presents a streamlined public involvement process for gaining stakeholder support and producing viable water resource solutions.