Throughout the ’80s and ’90s, the Environmental Protection Agency (EPA) increased the number of regulated drinking water contaminants to 91. Most of these regulations were relatively simple to understand, as EPA set a Maximum Contaminant Level (MCL) for each contaminant. Compliance was typically based on an annual average of quarterly samples at the entry point to the distribution system.

A few of these regulations were a tad more complicated. In 1991, the Surface Water Treatment Rule (SWTR) and the Total Coliform Rule (TCR) established treatment techniques for microbial protection for surface water systems and groundwater under the direct influence of surface water.
In 1993, the Lead and Copper Rule (LCR) incorporated not only optimized corrosion control, but also lead service line replacement and public education for compliance with this regulation. Most utilities were able to figure out these regulations, but the recent experience with lead in the District of Columbia shows that the drinking water community still has a lot of learn about corrosion control and research should not stop once a regulation is finalized.

Future regulations

So what does the future hold for drinking water regulations?
The SWTR, the TCR and the LCR were the start of a trend towards much more complicated regulations. The Stage 1 Disinfectants/Disinfection By-Products Rule (D/DBPR) and the Interim Enhanced Surface Water Treatment Rule that were finalized in 1998 have over twenty different violation codes (i.e., different ways to violate these regulations).
The Stage 2 Disinfection By-Products Rule and Long-Term 2 Enhanced Surface Water Treatment Rule that were proposed in 2003 are equally as complicated.
Even a regulation with a simple MCL will likely be targeting a “hard-to-treat” contaminant in the future. Arsenic is the current “poster child” for a “hard-to-treat” contaminant and many systems, both large and small, in the west will struggle to comply with this regulation in the very near future.
Systems are supposed to be in compliance with the arsenic regulation in January 2006 and that deadline is coming up fast. Other “hard-to-treat” contaminants that will likely be regulated in the future include perchlorate and Chromium-VI. Others will likely be found as new analytical techniques are developed and who knows what the next “contaminant du jour” will be?

Compliance struggles

Drinking water systems will continue to struggle with simultaneous compliance with all of these regulations.
The recent experience with lead in Washington, D.C. is one example of a lack of a complete understanding of the impact that one regulation may have on another. Without having all of the data needed for a definitive analysis, it appears that the treatment changes (enhanced coagulation and switching to chloramines) the utility instituted to comply with the Stage 1 D/DBPR contributed to the sudden increase in lead levels.
Finally, future regulations will start to shift from long-term endpoints such as cancer based on 70 years of exposure to shorter-term endpoints. Atrazine is the first contaminant in which the regulated endpoint is shifting to reproductive and development endpoints such as altered pregnancy maintenance and alteration of the estrous cycle. These are not the types of issues that many utilities would want to mention in their Consumer Confidence Reports. The reproductive health effects data from Disinfection By-Products is much more debatable, but the potential exposure is large. Many traditional MCLs that were based on cancer endpoints will likely be reexamined in the future from a reproductive and developmental perspective.

What does this mean for the standards?

Utilities will likely have to monitor more frequently and compliance will likely be based on a shorter timeframe, maybe even a single sample. For compliance with a single sample to be practical, online monitoring tools will be needed and these just don’t exist for almost all of the regulated contaminants at this time.
In addition to these shorter timeframes, utilities will have to learn to comply with more complex regulations and still maintain simultaneous compliance with all of the existing regulations.