The LT2 Rule requires water utilities drawing from surface water or groundwater under direct influence of surface water (GWUDI) to monitor and report on treatment efforts and results as they pertain to Cryptosporidium, Giardia lamblia, and/or E. coli. LT2 compliance is meant to control the risk of microbial pathogens while balancing trade-offs with disinfection byproducts (DBPs).
In theory, LT2 compliance is a simple process. Many water treatment plants (WTPs) are able to achieve compliance by adding an LT2 polishing cartridge at the end of the treatment train. However, water systems are anything but simple, and many things can go awry that can cause a once-compliant plant to fall out of compliance. In addition, if the proper steps are not taken in the beginning, a compliance solution may fail at or shortly after startup.