United States
Environmental Protection
Agency
Office of Water
4603
EPA811-F-96-005
May 1996
vvEPA
EPA EFFORTS TO CONTROL
MICROBIAL AND BYPRODUCT RISK
Three new rules [Disinfectants/Disinfection Byproducts Rule (D/DBPR) - proposed 7/94 (59 FR 38668), Enhanced Surface
Water Treatment Rule (ESWTR) - proposed 7/94 (59 FR 38832), Information Collection Rule (ICR) - proposed 2/94 (59
PR 6332) and promulgated 5/96] have been developed in a regulatory negotiation, with participation from State and local
health and regulatory agencies and elected officials, consumer groups, environmental groups, and the drinking water
industry. The tentative implementation schedule is as follows:
PROJECTED EFFECTIVE DATES FOR ICR, D/DBPR, AND ESWTR
SYSTEM TYPE
Surface water
systems2
Ground water
systems2
POPULATION
SERVED
;> 100,000
10,000-99,999
< 10,000
;> 100,000
10,000-99,999
< 10,000
ICR1
micro
2/97
NA
NA
NA
NA
NA
DBP
2/97
NA
NA
2/97
NA
NA
duration
18 mos.
NA
NA
18 mos.
12 mos.3
NA
D/DBPR
Stage 1
?
?
?
7
?
?
Interim
ESWTR
?
7
NA
NA
NA
NA
(1) -.ICR monitoring, divided into microbiological occurrence and DBP occurrence, may begin when noted.
Also, some systems will be required to conduct studies (see below for details).
(2) - Surface water systems include those which use ground water under the direct influence of surface water.
Ground water systems are those which use only ground water not under the direct influence of surface water.
(3) - Limited requirements for treatment studies apply only to systems serving £50,000 people.
Under these rules, the following contaminants and disinfectants will be regulated for the first time: (ESWTR) -
Cryptosporidium; (D/DBPR) - chloroform, bromoform, bromodichloromethane, dibromochloromethane, dichloroacetic
acid, trichloroacetic acid, bromate, chlorite, chloral hydrate, chlorine, chloramines, and chlorine dioxide. The rales will
apply to community water systems and nontransient noncommunity water systems. The ESWTR will also apply to
transient noncommunity water systems.
Information Collection Rule
The proposed ICR would require collection of occurrence and treatment data and characterization for disinfectants,
disinfection byproducts, and microorganisms (including Giardia, Cryptosporidium, and viruses). Also, some surface water
systems serving ^ 100,000 and ground water systems serving z 50,000 must complete bench- or pilot-scale studies of
disinfection byproduct precursor removal by activated carbon or membranes by 7/99. These data, in addition to concurrent
health effects and technology research, will be used to develop the ESWTR and Stage 2 of the D/DBPR.
Interim Enhanced Surface Water Treatment Rule
The proposed interim ESWTR included options to be refined based on ICR microbiological data. Generally, these include
1) requirements that surface water systems with poorer quality source waters remove microbiological contaminants above
levels currently required by the SWTR (99.9% for Giardia and 99.99% for viruses); and 2) making no changes if the
current SWTR is determined adequate. In addition, systems would be subject to sanitary surveys and may be required to
treat for Cryptosporidium. EPA plans to publish a Notice of Availability containing ICR microbial occurrence data and
EPA's preferred ESWTR option for public comment in mid- to late-1998. A long-term ESWTR will be developed for
systems serving < 10,000 and may include revisions to the interim ESWTR for systems ^ 10,000.
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Disinfectants/Disinfection Byproducts Rule
This rule will be promulgated in two stages. The proposed Stage 1 D/DBPR would lower the existing maximum
contaminant level (MCL) for total trihalomethanes from 0.10 mg/1 to 0.080 mg/1 and extend the MCL to all system sizes,
establish six new MCLs and maximum residual disinfectant levels (MRDL), and require enhanced coagulation or enhanced
precipitative softening for certain systems. Stage 2, which will incorporate ICR data and new research data, will be
developed by regulatory negotiation or a similar consensus process to begin hi 2000.
PROPOSED D/DBPR STAGE tREdyiRElVlEISITS8
Compound
Total trihalomethanes (TTHM)3
Haloacetic acids (five) (HAA5)4
Bromate5
Chlorite6
Chlorine7
Chloramines7
Chlorine dioxide7
MCL/MRDL1
0.080 mg/l
0.060 mg/l
0.010 mg/l
1 .0 mg/l
4.0 mg/l
4.0 mg/l
0.8 mg/l
Compliance Based On2
running annual average
running annual average
running annual average
monthly average
running annual average
running annual average
daily sampling
(1) - Both MCLs and MRDLs are enforceable.
(2) - Samples for all compounds except chlorine dioxide and bromate taken at specified distribution system
locations. Chlorine dioxide and bromate taken at entrance to distribution system.
(3) - Sum of chloroform, bromodichloromethane, dibromochloromethane, and bromoform concentrations.
(4) - Sum of mono-, di-, and trichloroacetic acids and mono- and dibromoacetic acid concentrations.
(5) - Required only for systems using ozone.
(6) - Required only for systems using chlorine dioxide.
(7) - Required only for systems using this disinfectant.
(8) - Stage 2 MCLs of 0.040 mg/l for TTHMs and 0.030 mg/l for HAA5 were proposed in Stage 1.
In addition to the above, the proposed Stage 1 D/DBPR would require systems using surface water (or ground water under
the direct influence of surface water) and conventional filtration treatment to meet a treatment technique for removal of
disinfection byproduct precursors (compounds that react with disinfectants to form DBFs), measured as percent removal of
total organic carbon, unless the system meets specified avoidance criteria.
ESTIMATED COSTS FOR THE ICR, D/DBPR,(Stage 1), AND ESWTR
RULE
ICR2
D/DBPR
Stage 1
ESWTR
CAPITAL
(?)
$57 mil
$4.4 bil
$3.7 bil3
OPERATIONS &
MAINTENANCE
$0
$489 mil/yr
TBD
TOTAL1
($/yr)
NA
$1.035 bil
$400 mil3
MONITORING
$72 mil
$58 mil/yr
TBD
STATE
IMPLEMENTATION
$0
$23 mil/yr
$3 mil/yr
(1) - Total annual costs are the sum of annualized capital costs plus annual operations and maintenance costs.
(2) - ICR capital costs are for bench- and pilot-scale studies. ICR monitoring costs are total, not annual, costs.
(3) - Insufficient data for accurate estimate. Costs indicated are. only for one proposed option that is capital
cost intensive. Total costs only include amortized capital costs.
TBD - to be determined.
For more information, contact the Safe Drinking Water Hotline, 1-800-426-4791.
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