In last month’s Ampersand, we briefly discussed the Stage 2 Disinfection By-Product Rule and measures that drinking water utilities can take to successfully comply with the DBPR2. This article focuses on the final Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR or LT2). This rule will impact all systems that have surface water or groundwater under the influence of surface water as the primary source.

The LT2 rule is intended to protect drinking water supplies from microbial pathogens, such as bacteria, protozoa, and viruses. It builds upon earlier rules issued by the EPA that balance treatment for removal of microbial pathogens and the formation of Disinfection By-Products. Some of the earlier rules included the Long-Term 1 Enhanced Surface Water Treatment Rule, and the Surface Water Treatment and Interim Enhanced Surface Water Treatment Rules. Many of the requirements were a result of the 1993 cryptosporidiosis (the illness caused by Cryptosporidium) outbreak in Milwaukee, WI, that caused more than 400,000 people to experience intestinal illness, with some 4,000 hospitalizations and at least 50 deaths attributed.

The LT2 rule is more complex than the previously discussed DBP2R. The main requirements of the rule include monitoring for microbial pathogens in the source water, treatment for Cryptosporidium removal, requirements for open storage reservoirs, and optimization of treatment and disinfection practices.

The first of two required rounds of monitoring is the most immediate impact of this rule to utilities. The above table summarizes the requirements for each category of system defined in the LT2 rule.

There are four ways in which a system may avoid monitoring. These are:

1. Filtered systems must demonstrate at least 5.5 log inactivation of Cryptosporidium

2. Unfiltered systems must demonstrate at least 3.0 log inactivation of Cryptosporidium

3. Systems can agree to upgrade to provide these levels

4. Systems can submit "grandfathered" data that meets the QA/QC requirements of the LT2 rule and began no earlier than January 1999.

After the initial round of monitoring, systems will receive a classification that determines what, if any, additional treatment levels for Cryptosporidium removal may be required beyond conventional treatment. It is important to note that states may have more stringent requirements than the Federal rules we have summarized. You should check with you state’s contact as listed in the following table.