[Code of Federal Regulations]
[Title 40, Volume 21]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR141.63]

[Page 440]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 141_NATIONAL PRIMARY DRINKING WATER REGULATIONS--Table of Contents
 
     Subpart G_National Primary Drinking Water Regulations: Maximum 
       Contaminant Levels and Maximum Residual Disinfectant Levels
 
Sec. 141.63  Maximum contaminant levels (MCLs) for microbiological 
contaminants.

    (a) The MCL is based on the presence or absence of total coliforms 
in a sample, rather than coliform density.
    (1) For a system which collects at least 40 samples per month, if no 
more than 5.0 percent of the samples collected during a month are total 
coliform-positive, the system is in compliance with the MCL for total 
coliforms.
    (2) For a system which collects fewer than 40 samples/month, if no 
more than one sample collected during a month is total coliform-
positive, the system is in compliance with the MCL for total coliforms.
    (b) Any fecal coliform-positive repeat sample or E. coli-positive 
repeat sample, or any total coliform-positive repeat sample following a 
fecal coliform-positive or E. coli-positive routine sample constitutes a 
violation of the MCL for total coliforms. For purposes of the public 
notification requirements in subpart Q, this is a violation that may 
pose an acute risk to health.
    (c) A public water system must determine compliance with the MCL for 
total coliforms in paragraphs (a) and (b) of this section for each month 
in which it is required to monitor for total coliforms.
    (d) The Administrator, pursuant to section 1412 of the Act, hereby 
identifies the following as the best technology, treatment techniques, 
or other means available for achieving compliance with the maximum 
contaminant level for total coliforms in paragraphs (a) and (b) of this 
section:
    (1) Protection of wells from contamination by coliforms by 
appropriate placement and construction;
    (2) Maintenance of a disinfectant residual throughout the 
distribution system;
    (3) Proper maintenance of the distribution system including 
appropriate pipe replacement and repair procedures, main flushing 
programs, proper operation and maintenance of storage tanks and 
reservoirs, and continual maintenance of positive water pressure in all 
parts of the distribution system;
    (4) Filtration and/or disinfection of surface water, as described in 
subpart H, or disinfection of ground water using strong oxidants such as 
chlorine, chlorine dioxide, or ozone; and
    (5) For systems using ground water, compliance with the requirements 
of an EPA-approved State Wellhead Protection Program developed and 
implemented under section 1428 of the SDWA.

[54 FR 27566, June 29, 1989; 55 FR 25064, June 19, 1990, as amended at 
65 FR 26022, May 4, 2000]

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