United States Office of Water EPA 815-F-98-009
Environmental Protection (4607) December 1998
Agency DRAFT
4>EPA Interim Enhanced Surface Water
Treatment Rule
Disinfection of drinking water is one of the major public health advances in the 20th century.
One hundred years ago, typhoid and cholera epidemics were common through American cities
and disinfection was a major factor in reducing these epidemics. However, the disinfectants
themselves can react with naturally-occurring materials in the water to form unintended
byproducts which may pose health risks.
In the past ten years, however, we have learned that there are specific microbial pathogens, such
as Cryptosporidium, that are highly resistant to traditional disinfection practices. In 1993,
Cryptosporidium caused 400,000 people in Milwaukee to experience intestinal illness. More
than 4,000 were hospitalized, and at least SO deaths have been attributed to the disease. There
have also been cryptosporidiosis outbreaks in Nevada, Oregon, and Georgia over the past several
years. In addition, the disinfectants themselves can react with naturally-occurring materials in the
water to form unintended byproducts which may-pose health risks.
Amendments to SDWA in 1996 require EPA to develop rules to balance the risks. It is important
to strengthen protection against microbial contaminants, especially Cryptosporidium, and at the
same time, reduce potential health risks from disinfection byproducts. The new Interim
Enhanced Surface Water,Treatment Rule and Stage 1 Disinfectants and Disinfection Byproducts
Rule are the first of a sefof rules under the Amendments. This fact sheet focuses on the Interim
Enhanced Surface Water Treatment Rule. A separate fact sheet focuses on the Stage 1
Disinfectants and Disinfection Byproducts Rule (EPA 815-F-98-010).
EPA's Science Advisory Board concluded in 1990 that exposure to microbial contaminants such
as bacteria, viruses, and protozoa (e.g., Giardia lamblia and Cryptosporidium) was likely the
greatest remaining health risk management challenge for drinking water suppliers. Acute health
effects from exposure to microbial pathogens is documented and associated illness can range
from mild to moderate cases lasting only a few days to more severe infections that can last
several weeks and may result in death for those with weakened immune systems.
WHO MUST COMPLY WITH THE
RULE* "-:: . :- \ --, .
The Interim Enhanced Surface Water Treatment Rule applies to public water systems that
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use surface water or ground water under the direct influence of surface water (GWUDI)
and serve at least 10,000 people. In addition, States are required to conduct sanitary
surveys for all surface water and GWUDI systems, including those that serve fewer than
10,000 people.
I J1IIA T DOES- THE RULE REQUIRE? I
The Interim Enhanced Surface Water Treatment Rule amends the existing Surface Water
Treatment Rule to strengthen microbial protection, including provisions specifically to
address Cryptosporidium, and to address risk trade-offs with disinfection byproducts.
The final rule includes treatment requirements for waterbome pathogens, e.g.,
Ciyptosporidium. In addition, systems must continue to meet existing requirements for
Giardia lamblia and viruses. Specifically, the rule includes: -
• Maximum contaminant level goal (MCLG) of zero for Cryptosporidium
• 2-log Cryptosporidium removal requirements for systems that filter
• Strengthened combined filter effluent turbidity performance standards
• Individual filter turbidity monitoring provisions
• Disinfection profiling and benchmarking provisions
• Systems using ground water under the direct influence of surface water
•now subject to the new rules dealing with Crypdosporidium
• Inclusion of Cryptosporidium in the watershed control r quirements for
unfiltered public water systems
• Requirements for covers on new finished water reservoirs
• Sanitary surveys, conducted by States, for all surface water systems
regardless of size
The rule, with tightened turbidity performance criteria and individual filter monitoring
reciuirements, is designed to optimize treatment reliability and to enhance physical
removal efficiencies to minimize the Cryptosporidium levels in finished water. Turbidity
requirements for combined filter effluent will remain at least every four hours, but
continuous monitoring will be required for individual filters. In addition, the rule includes
disinfection profiling and benchmarking provisions to assure continued levels of
microbial protection while facilities take the necessary steps to comply with new DBP
standards. -
I WHAT THE4’COMPEJANCEDEI4DLIES? I
States have two years from publication to adopt and implement the requirements
of this regulation. Simultaneous compliance with the Stage I Disinfection
Byproduct Rule, promulgated at the same time, will be achieved as follows:
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Public water systems that use surface water or ground water under the direct
influence of surface water, either in whole or in part, and serve a population of
10,000 or more generally have three years from Federal promulgation to comply
with requirements of this rule, except for disinfection pm filing and benchmarking,
which require systems to begin sampling after three months. In cases where
capital improvements are needed to comply with the rule, States may grant
systems up to an additional two years to comply.
WE4TARE THE COSISAND BENEFI7S
OF THE RULEt: - -. -
EPA estimates that implementation of the Interim Enhanced Surface Water Treatment
Riile will:
Improve public health by mcreasing the level of protection from exposure
to Cryptosporidium and other pathogens (i.e., Giardia, or other
waterborne bacterial or viral pathogens) in drinking water supplies through
improvements in filtration at water, systems;
• Significantly reduce the level of Cryptosporidium in finished drinking
water supplies through improvements in filtration at water systems (i.e.,
revised turbidity requirements);’
• Decrease the likelihood of endemic (constant low-level presence of a
disease or infection) illness from Ci tosporidium by 110,000 to 463,000
cases annually and related health costs, as well as incidences of illness
from Giardia and other waterborne pathogens; and
• Reduce the likelihood of the occurrence of outbreaks of cryptosporidiosis
(illness from Cryptosporidium) and their associated economic costs by
providing a larger margin of safety against such outbreaks for some
systems.
The total annualized national cost for implementing the Interim Enhanced Surface Water
Treatment Rule is $307 million. EPA believes that the benefits exceed the costs. The
rule will result in increased costs to public water systems for improved turbidity
treatment, monitoring, disinfection benchmarking and covering new finished water
reservoirs, as well as State implementation costs.
EPA estimates that 92 percent of households (60 million) will incur an increase in their
water bill of less than $1 per month; 7 percent of households (5 million) will incur an
increase in their water bills of between $1 - $5 per month; and less than 1 percent (23,000
households) will incur an increase of more than $5 per month (about $8 per month).
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A series of guidance manuals is planned to support the Interim Enhanced Surface Water
Treatment Rule and the Stage I Disinfectants/Disinfection Byproducts Rule. The
manuals will aid EPA, State agencies and affected public water systems in implementing
the two interrelated rules, and will help to ensure that implementation among these
groups is consistent. EPA anticipates that the manuals will be available for review in
early 1999.
The manuals will include:
Disinfection Benchmarking Guidance Manual
Objective: To help determine if a disinfection profile (an evaluation of current
disinfection practice) is required and how to do one; when a disinfection benchmark must
be determined and how to extract it from the profile; and how a public water system must
use the benchmark, in consultation with the State, to assure protection from microbial
risk is maintained when the system changes disinfection practice.
Contents: The manual provides detailed information on the following subjects:
applicability of the profiling and benchmarking requirements to public water systems;
procedures for generating a disinfection profile, including example profiles; methods for
calculating the disinfection benchmark, including example calčulations; the use of the
benchmark in modifying disinfection practices, communicating with the state, and
assessing significant changes to disinfection practices; te development of the profiling
and benchmarking regulations; the significance of the log inactivation concept and CT
values for inactivations achieved by various disinfectants; and the determination of
contact time.
Turbidity Guidance Manual
Objective: The first section provides technical information regarding specific
requirements of the Interim Enhanced Surface Water Treatment Rule relating to turbidity
and is intended for experienced operators and others in the regulated comn unity. The
second section of the document provides background on concepts surrounding turbidity
and serves as a primer for less experienced operators and individuals.
Contents: The first section contains key regulatory requirements including combined
filter effluent monitoring and individual filter monitoring; recordkeeping and reporting
requirements; additional compliance issues such as compliance schedule, public
notification, variances/exemptions, and follow-up action requirements; approved
methods and additional measurement and calibration issues; components and description
of an alter self-assessment; and components and description of a Comprehensive
Performance Evaluation.The second section of the manual includes more basic
information on turbidity; description of the particles (both natural and man-made) which
typically contribute to turbidity; discussion of typical steps in a treatment process and
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how turbidity is removed or created in each step; discussion of turbidity in different
source waters with an emphasis of how changes in source water effect turbidity; and
basic turbidimeter design.
Alternative Disinfectants and Oxidants Guidance Manual
Objective: To provide technical data and engineering information on disinfectants and
oxidants that are not as commonly used as chlorine, so that systems can evaluate their
options for developing disinfection schemes to control water quality problems such as
zebra mussels and Asiatic clams, and oxidation to control water quality problems
associated with iron and manganese.
Contents: The manual discusses six disinfectants and oxidants: ozone, chlorine dioxide,
potassium permanganate, chioramines, ozone/hydrogen peroxide combinations, and
ultraviolet light. A decision tree is provided to assist in evaluating which disinfectant(s)
is most appropriate given certain site-specific conditions (e.g., water quality conditions,
existing treatment and operator skill). The manual also contains a summary of existing
alternative disinfectants use in the United States and cost estimates for the use of
alternative disinfectants.
MIDBP Simultaneous Compliance Manual
Objective: To assist public water systems on complying simultaneously with various
drinking water regulations (e.g., Stage I Disinfectants and Disinfection Byproducts Rule,
Interim Enhanced Surface Water Treatment Rule, Lead and Copper Rule and the Total
Coliform Rule). The manual discusses operational problems systems may encounter
when implementating these rules.
Contents: The manual provides detailed information on the requirements in the Stage 1
Disinfectants and Disinfection Byproducts Rule and the Interim Enhanced Surface Water
Treatment Rule.
Guidance Manual for Conducting Sanitary Surveys of Public Water Systems
Objective: The guidance manual provides an overview of how to conduct a sanitary
survey of all water systems using surface water and ground water under the direct
influence of surface water. It is intended to help state agencies improve their sanitary
survey programs where needed.
Contents: The manual provides information about the objective and regulatory context
of sanitary surveys. It covers four’principal stages of a sanitary survey: planning,
including preparatory steps to be taken by inspectors before conducting the onsite
portion; conducting the onsite survey; compiling a sanitary survey report; and performing
follow-up activities.
Unfiltered Water Supply Guidance Manual
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Objective: To supplement the existing Interim Surface Water Treatment Rule guidance
for unfiltered surface water supplies and to identify the issues and requirements
associated with the new regulations.
Contents: This manual discusses provisions of the Interim Enhanced Surface Water
Treatment Rule that will impact unfiltered surface water and; provides guidance on the
development of watershed control programs or enhancements of existing watershed
control programs to address Cryptosporidium. In addition, it provides information and
guidance on monitoring for Cryptosporidium.
Uncovered Finished Water Reservoirs
Contents: The manual provides detailed information on the following subjects:
developing and implementing comprehensive open finished water reservoir management
plans based on site-specific conditions; identifying potential sources of contamination in
open finished water reservoirs and potential mitigation measures; employing different
methods to control the degradation of water quality while it resides in the reservoir;
monitoring schemes that can be used to characterize water quality and identify water
quality degradation before it becomes severe and is difficult to correct. -
For more information, contact EPA’s Safe Drinking Water Hotline, 1 (800) 426-4791, or
see the Office of Ground Water and Drinking Water web page at
http://www.epa.gov/safewater/ standards.html.
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