EPA Efforts to Control Microbial and Byproduct Risk

United States Environmental Protection Agency
Office of Water 4603
EPA 811-F-96-005
May 1996

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The final Information Collection Rule (ICR) was published in the Federal Register on May 14, 1996. This FR notice finalizes requirements for monitoring microbial contaminants and disinfection byproducts by large public water systems (PWSs). It also requires large PWSs to provide operating data and a description of their treatment plant design. Finally, it requires large PWSs to conduct either bench- or pilot-scale testing of advanced treatment techniques.

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 FR 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:

(1)

- ICR monitoring, divided into microbiological occurrence and DBP occurrence, may begin when noted. Also, some systems will be required to conduct studies (see Information Collection Rule 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.

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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 rules 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 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.

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/l to 0.080 mg/l 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 in 2000.

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(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.

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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 DBPs), measured as percent removal of total organic carbon, unless the system meets specified avoidance criteria.

(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.

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For more information, contact the Safe Drinking Water Hotline, 1-800-426-4791.

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Federal Register Notice on May 14, 1996