dEPA United States Environmental Protection Agency Comprehensive Surface Water Treatment Rules Quick Reference Guide: Systems Using Slow Sand, Diatomaceous Earth, or Alternative Filtration Overview of the Rules Title Purpose General Description Surface Water Treatment Rule (SWTR) - 40 CFR 141.70-141.75 Interim Enhanced Surface Water Treatment Rule (IESWTR) - 40 CFR 141.170-141.175 Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) - 40 CFR 141.500-141.571 Improve public health protection through the control of microbial contaminants, particularly viruses, Giardia, and Cryptosporidium. The Surface Water Treatment Rules: >• Applies to all public water systems (PWSs) using surface water or ground water under the direct influence of surface water (GWUDI), otherwise known as "Subpart H systems." >. Requires ajj Subpart H systems to disinfect. >. Requires Subpart H systems to filter unless specific filter avoidance criteria are met. >. Applies a treatment technique requirement for control of microbials. Overview of Requirements The purpose of this table is show how the requirements for the IESWTR and LT1 ESWTR build on the existing requirements established in the original SWTR. APPLICABILITY: PWSs that use surface water or ground water under the direct influence of surface water (Subpart H) that practice slow sand, diatomaceous earth or alternative filtration. Population Served Regulated Pathogens Residual Disinfectant Requirements Turbidity Performance Standards Disinfection Profiling & Benchmarking Sanitary Surveys (state requirement) >1 0,000 < 10,000 99.99% (4-log) removal/inactivation of viruses 99.9% (3-log) removal/inactivation of Giardia lamblia 99% (2-log) removal of Cryptosporidium Entrance to distribution system ( > 0.2 mg/L) Detectable in the distribution system Combined Filter Effluent - Slow Sand and Diatomaceous Earth Combined Filter Effluent - Alternative Systems must profile inactivation levels and generate benchmark, if required CWS: Every 3 years NCWS: Every 5 years Covered Finished Reservoirs/Water Storage Facilities (new construction only) Operated by Qualified Personnel as Specified by State Final Rule Dates SWTR 1989 / •/ / ^ ,/ / V V ~ ^ IESWTR 1998 V N/A (except for sanitary survey provisions) Regulated under SWTR Regulated under SWTR V Regulated under SWTR Regulated under SWTR Regulated under SWTR ^ V ^ ^ Regulated under SWTR LT1 ESWTR 2002 ^ Regulated under SWTR Regulated under SWTR ^ Regulated under SWTR Regulated under SWTR Regulated under SWTR ^ ^ Regulated under IESWTR ^ Regulated under SWTR (CWS) Community Water System (NCWS) Non-community Water System ------- Turbidity Turbidity is measured as Combined Filter Effluent (CFE) for slow sand, diatomaceous earth, and alternative filtration. The CFE 95th % value and CFE maximum value for slow sand and diatomaceous earth were not lowered in the IESWTR and LT1ESWTR since these filtration technologies are assumed to provide 2-log Cryptosporidium removal with the turbidity limits established by SWTR. Alternative filtration technologies (defined as filtration technologies other than conventional, direct, slow sand, or diatomaceous earth) must demonstrate to the state that filtration and/or disinfection achieve 3-log Giardia and 4-log virus removal and/or inactivation. The IESWTR and LT1 ESWTR also require alternative filtration technolo- gies to demonstrate 2-log Cryptosporidium removal. Turbidity: Monitoring and Reporting Requirements Turbidity Type and Reporting Requirements (Reports due by the 10th day of the following month the system serves water to the public.) Slow Sand & Diatomaceous Earth Alternative x Membranes x Cartridges x Other CFE 95% CFE Max CFE 95% CFE Max Monitoring/ Recording Frequency At least every 4 hours* At least every 4 hours* At least every 4 hours* At least every 4 hours* SWTR As of June 29, 1993 <1 NTU 5NTU <1 NTU 5 NTU IESWTR >1 0,000 people As of January 1, 2002 Regulated under SWTR Regulated under SWTR Established by state Established by state LT1 ESWTR < 10,000 people As of January 1,2005 Regulated under SWTR Regulated under SWTR Established by state (not to exceed 1 NTU) Established by state (not to exceed 5 NTU) *Monitoring frequency may be reduced by the state to once per day for systems using slow sand or alternative filtration. Monitoring frequency may be reduced by the state to once per day for systems serving 500 or fewer people regardless of type of filtration used. CFE Turbidity: Reporting Requirements Report to State: SWTR Measurements IESWTR Measurements LT1 ESWTR Measurements** Total number of monthly measurements Total number of monthly measurements Total number of monthly measurements Within 10 days after the end of the month: Number and percent less than or equal to designated 95th percent!le turbidity limits Number and percent less than or equal to designated 95th percentile turbidity limits Number and percent less than or equal to designated 95th percentile turbidity limits Date and value exceeding 5 NTU Date and value exceeding 5 NTU for slow sand and diatomaceous earth or maximum level set by state for alternative filtration Date and value exceeding 5 NTU for slow sand and diatomaceous earth or maximum level set by state for alternative filtration Within 24 hours: Exceedances of 5 NTU for CFE Exceedances of 5 NTU for slow sand and diatomaceous earth or maximum CFE level set by state for alternative filtration Exceedances of 5 NTU for slow sand and diatomaceous earth or maximum CFE level set by state for alternative filtration Systems serving fewer than 10,000 people must begin complying with these requirements beginning January 1, 2005. ------- Disinfection Disinfection must be sufficient to ensure that the total treatment process (disinfection plus filtration) of the system achieves at least: >• 99.9% (3-log) inactivation and/or removal of Giardia lamblia. >- 99.99% (4-log) inactivation and/or removal of viruses. Cryptosporidium must be removed by filtration and no inactivation credits are currently given for disinfection. Systems must also comply with the maximum residual disinfectant level (MRDL) requirements specified in the Stage 1 Disinfectants/ Disinfection Byproducts Rule (Stage 1 DBPR). Residual Disinfectant Monitoring and Reporting Requirements Location Concentration Monitoring Frequency Reporting (Reports due 10th of the following month) Entry to distribution system. Residual disinfectant concentration cannot be < 0.2 mg/L for more than 4 hours. Continuous, but states may allow systems serving 3,300 or fewer persons to take grab samples from 1 to 4 times per day, depending on system size. Lowest daily value for each day, the date and duration when residual disinfectant was < 0.2 mg/L, and when state was notified of events where residual disinfectant was < 0.2 mg/L. Distribution system - same location as total coliform sample location(s). Residual disinfectant concentration cannot be undetectable in greater than 5% of samples in a month, for any 2 consecutive months. Heterotrophic plate count (HPC) < 500/mL is deemed to have detectable residual disinfectant. Same time as total coliform samples. Number of residual disinfectant or HPC measurements taken in the month resulting in no more than 5% of the measurements as being undetectable in any 2 consecutive months. ------- Disinfection Profiling and Benchmarking Requirements A disinfection profile is the graphical representation of a system's microbial inactivation over 12 consecutive months. A disinfection benchmark is the lowest monthly average microbial inactivation value. The disinfection benchmark is used as a baseline of inactivation when considering changes in the disinfection process. Disinfection Profiling and Benchmarking Requirements Under IESWTR & LT1ESWTR The purpose of disinfection profiling and benchmarking is to allow systems and states to assess whether a change in disinfection practices creates a microbial risk. Systems should develop a disinfection profile that reflects Giardia lamblia inactivation (systems using ozone or chloramines must also calculate inactivation of viruses), calculate a benchmark (lowest monthly inactivation) based on the profile, and consult with the state prior to making a significant change to disinfection practices. REQUIREMENT IESWTR LT1ESWTR AFFECTED SYSTEMS: Community, non-transient non-community, and transient systems. Community and non-transient non-community systems only. BEGIN PROFILING BY: April 1,2000 > July 1, 2003 for systems serving 500-9,999 people. > January 1, 2004 for systems serving fewer than 500 people. FREQUENCY & DURATION: Daily monitoring for 12 consecutive calendar months to determine the total logs of Giardia lamblia inactivation (and viruses, if necessary) for each day in operation. Weekly inactivation of Giardia lamblia (and viruses, if necessary), on the same calendar day each week over 12 consecutive months. STATES MAY WAIVE DISINFECTION PROFILING REQUIREMENTS IF: TTHM annual average <0.064 mg/L and HAA5 annual average <0.048 mg/L: > Collected during the same period. > Annual average is arithmetic average of the quarterly averages of four consecutive quarters of monitoring. > At least 25% of samples at the maximum residence time in the distribution system. > Remaining 75% of samples at representative locations in the distribution system. One TTHM sample <0.064 mg/L and one HAA5 sample <0.048 mg/L: > Collected during the month of warmest water temperature; AND > At the maximum residence time in the distribution system. Samples must have been collected after January 1, 1998. DISINFECTION BENCHMARK MUST BE CALCULATED IF: Systems required to develop a disinfection profile and are considering any of the following: > Changes to the point of disinfection. > Changes to the disinfectant(s) used. > Changes to the disinfection process. > Any other modification identified by the state. Systems must consult the state prior to making any modifications to disinfection practices. Same as IESWTR, and systems must obtain state approval prior to making any modifications to disinfection practices. Office of Water (4606) EPA816-F-04-002 www.epa.gov/safewater August 2004 ------- |