More than ever, drinking water utility management and operation is a challenging responsibility in today’s regulatory environment. By the beginning of 2006, the U.S. EPA had implemented 87 primary drinking water standards and 15 secondary standards, according to the National Drinking Water Clearinghouse. Keeping up with all of these rules (as well as all of your day-to-day tasks) can be quite difficult. To help you through the regulatory maze, this article will summarize information from various EPA documents about two of the most recent major rules, the Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBP rule or DBPR, Stage 2) and the Long Term 2 Enhanced Surface Water Treatment Rule (LT2 rule or LT2ESWTR).
Evolution of regulations
Since the passing of the Safe Drinking Water Act (SDWA) in 1974, we have learned that specific microbial pathogens, such as Cryptosporidium, can cause serious illness and are resistant to traditional water disinfection practices. In addition, we have learned that water disinfectants can react with naturally occurring minerals to form disinfection byproducts (DBPs), which also pose health concerns.
To respond to these new threats, amendments to the SDWA in 1996 require the EPA to develop rules to balance the risks between pathogens and disinfection byproducts. As the first phase of this requirement, the Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1 DBP rule) was promulgated in December 1998 to reduce exposure to disinfection byproducts for customers of community water systems and nontransient 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.
The Interim Enhanced Surface Water Treatment Rule (IESWTR) was also promulgated in December 1998, but this rule was made to improve control of microbial contaminants, particularly Cryptosporidium, in systems using surface water, or groundwater under the direct influence (GWUDI) of surface water, that serve 10,000 or more persons. As the small-system counterpart to the IESWTR, the Long Term 1 Enhanced Surface Water Treatment Rule was finalized in January 2002 and strengthens control of microbial contaminants for systems serving fewer than 10,000 people.
The Stage 2 DBP rule and the LT2 rule are the second phase of rules required by Congress to help balance the risks between pathogens and disinfection byproducts. These rules strengthen protection against microbial contaminants, especially Cryptosporidium, and at the same time, reduce potential health risks of DBPs.
Stage 2 DBP rule Building upon the Stage 1 DBP rule, the Stage 2 DBP rule was published in the Federal Register on Jan. 4, 2006. This rule is intended to reduce potential cancer and reproductive and developmental health risks from DBPs in drinking water through more stringent methods for determining compliance.
Requirements. Under the Stage 2 DBP rule, community and nontransient noncommunity water systems that add and/or deliver water that is treated with a primary or residual disinfectant other than ultraviolet light must conduct an evaluation of their distribution systems, called an Initial Distribution System Evaluation (IDSE), to identify locations with high DBP concentrations. These locations must then be used by the systems as the sampling sites for Stage 2 DBP rule compliance monitoring. The rule requires two steps for the IDSE. First, the system must develop a plan of how they will approach the IDSE. There are four options: a very small system waiver, 40/30 certification, standard monitoring program (SMP) or system specific study (SSS). This plan must be submitted to the state or primacy agency with proposed DBP monitoring sites. After receiving approval, the system must conduct the IDSE with one year of DBP monitoring if the standard option is used.
Compliance with the maximum contaminant levels (MCLs) for trihalomethanes and five haloacetic acids will be calculated as an average at each compliance-monitoring location (instead of as a system-wide average as in previous rules). This approach is referred to as the locational running annual average (LRAA).
The Stage 2 DBP rule also establishes operational evaluation levels. A system that exceeds this level must conduct an operational evaluation (a review of operational practices) to determine ways to reduce DBP levels. This provides an early warning of possible future MCL violations, and allows the system to take proactive steps to remain in compliance.
Timeframe. The first step of the Stage 2 DBP rule is a multi-year process for water systems to determine where higher levels of DBPs occur in their distribution systems. These locations will become the new DBP monitoring sites, and corrective action will be taken if DBP levels are above the MCL. These actions could include small operational changes up to major facility construction. Depending on system size and the extent of needed construction, systems will begin the first year of compliance monitoring between 2012 and 2016 and must be in compliance with the Stage 2 DBP rule MCLs at the end of a full year of monitoring. (See Figure 1.)
Costs. As with most new regulations, the Stage 2 DBP rule will result in increased costs to public water systems and states. Although the rule applies to nearly 75,000 systems, only a small portion will be required to make treatment changes. The average cost of the rule is estimated at $79 million annually (using a 3% discount rate), according to the EPA.
LT2 rule
The LT2 rule was published in the Federal Register on Jan. 5, 2006. This rule is intended to improve public health by reducing illness due to Cryptosporidium and other disease-causing microorganisms in drinking water. Consumption of water that contains Cryptosporidium can cause gastrointestinal illness that can be fatal for people with weakened immune systems.
Requirements. The LT2 rule requires large public water systems (serving at least 10,000 people) that are supplied by surface water or GWUDI of surface water to conduct two years of monthly sampling for Cryptosporidium (and E. coli and turbidity for filtered systems). To reduce the cost of this monitoring, small water systems will monitor for E. coli for one year because it is less expensive to analyze. The systems will only monitor for Cryptosporidium if their E. coli results exceed specified concentration levels.
After monitoring is complete, filtered water systems will be classified in one of four treatment categories (bins) based on their monitoring results. The EPA expects the majority of systems to be placed in the lowest bin, and require no additional treatment. Systems placed in the higher bins will be required to provide additional treatment to reduce Cryptosporidium levels. Water systems in the higher bins and systems that do not filter their water will choose additional treatment options from a “microbial toolbox” of treatment and management processes.
Because of contamination risks, the LT2 rule also addresses uncovered finished water storage facilities, such as reservoirs. The rule requires systems that store treated water in uncovered facilities to either cover the facility or treat discharge to inactivate 4-log virus, 3-log Giardia lamblia and 2-log Cryptosporidium.
The LT2 rule also establishes disinfection benchmarking, in which systems are required to review their current level of microbial treatment before making significant changes in disinfection practices. This will help systems maintain protection against microbial pathogens as they strive to reduce DBPs under the Stage 2 DBP rule.
Timeframe. System monitoring start dates correspond to system size. Approximately three months before the monitoring start date, systems must submit a sampling schedule and sampling location description. Systems serving at least 100,000 people will begin monitoring in October 2006. Those serving 50,000 to 99,000 people will begin monitoring in April 2007. Systems serving 10,000 to 49,000 people will begin in April 2008. The smallest systems (serving less than 10,000 people) will begin monitoring for E. coli in October 2008 and Cryptosporidium in April 2010.
When these two years of monitoring are complete and bin classification is determined, systems will have approximately three years to implement any additional treatment requirements. Systems will then conduct a second round of monitoring six years after completing the initial round to determine if source water conditions have changed significantly. (See Figure 1.)
Costs. As with the Stage 2 DBP rule, the LT2 rule will result in increased costs to public water systems and states. The EPA estimates that the average annualized present value costs of the LT2 rule range from $92 to $133 million (using a 3% discount rate). Public water systems will be responsible for nearly all of the total cost (99%), and states will pick up the remaining 1%. The LT2 rule will also result in increased costs for households, with the EPA estimating an average annual household cost of $1.67 to $2.59.
Conclusion
Although there are many more details involved with these new rules, it is most important to understand the immediate requirements and the overall purpose of the Stage 2 DBP rule and the LT2 rule.
“Clean drinking water is a key ingredient to keeping people healthy and our economy strong,” said EPA Administrator Stephen L. Johnson in a press release about the new regulations. “Over the past seven years, EPA has worked collaboratively with stakeholders to develop regulations that will provide a balance between the need to disinfect drinking water and protect citizens from potentially harmful contaminants.”
More information about EPA drinking water regulations can be found at www.epa.gov/OGWDW/regs.html. This site, developed by the EPA’s Office of Ground Water and Drinking Water, lists current drinking water rules, proposed rules, the code of federal regulations, drinking water standards, and a wealth of other information, such as fact sheets, guidance manuals and more.
