| (a) Applicability. All public water systems shall properly
disinfect water before it is distributed to any customer and shall
maintain acceptable disinfectant residuals within the distribution
system.
(b) Minimum and maximum acceptable disinfectant concentrations.
Public water systems shall provide the minimum levels of disinfectants
in accordance with the provisions of this section. Public water systems
shall not exceed the maximum residual disinfectant levels (MRDLs)
provided in this section.
(1) The disinfection process used by public water systems
must ensure that water has been adequately disinfected before it enters
the distribution system.
(A) The disinfection process used by public water systems
treating surface water sources or groundwater sources that are under
the direct influence of surface water must meet the requirements of §290.111(d)
of this title (relating to Surface Water Treatment).
(B) The executive director may require the disinfection
process used by public water systems treating groundwater sources
that are not under the direct influence of surface water to meet the
requirements of §290.116 of this title (relating to Groundwater
Corrective Actions and Treatment Techniques).
(C) The disinfection process at other types of treatment
plants shall provide the level of disinfection required by the executive
director.
(2) The residual disinfectant concentration in the
water entering the distribution system shall be at least 0.2 milligram
per liter (mg/L) free chlorine or 0.5 mg/L chloramine.
(3) The chlorine dioxide residual of the water entering
the distribution system shall not exceed an MRDL of 0.8 mg/L.
(4) The residual disinfectant concentration in the
water within the distribution system shall be at least 0.2 mg/L free
chlorine or 0.5 mg/L chloramine.
(5) The running annual average of the free chlorine
or chloramine residual of the water within the distribution system
shall not exceed an MRDL of 4.0 mg/L.
(c) Monitoring requirements. Public water systems shall
monitor the performance of the disinfection facilities to ensure that
appropriate disinfectant levels are maintained. All monitoring conducted
pursuant to the requirements of this section must be conducted at
sites designated in the public water system's monitoring plan.
(1) Public water systems that treat surface water or
groundwater under the direct influence of surface water must verify
that they meet the disinfection requirements of subsection (b)(2)
of this section.
(A) Public water systems that treat surface water or
groundwater under the direct influence of surface water and sell treated
water on a wholesale basis or serve more than 3,300 people must continuously
monitor and record the disinfectant residual of the water entering
the distribution system. If there is a failure in the continuous monitoring
equipment, grab sampling every four hours may be conducted in lieu
of continuous monitoring, but for no more than five working days following
the failure of the equipment.
(B) Public water systems that treat surface water or
groundwater under the direct influence of surface water, serve 3,300
or fewer people and do not sell treated water on a wholesale basis
must monitor and record the disinfectant residual of the water entering
the distribution system with either continuous monitors or grab samples.
(i) If a system uses grab samples, the samples must
be collected on an ongoing basis at the frequency prescribed in the
following table.
Attached Graphic
(ii) The grab samples cannot be taken at the same time
and the sampling interval is subject to the executive director's review
and approval.
(iii) Treatment plants that use grab samples and fail
to detect an appropriate disinfectant residual must repeat the test
at four-hour or shorter intervals until compliance has been reestablished.
(2) Public water systems that treat groundwater or
that purchase and resell treated water must, upon the request of the
executive director, verify that they meet the disinfection requirements
of subsection (b)(2) of this section.
(3) Each treatment plant using chlorine dioxide must
monitor and record the chlorine dioxide residual of the water entering
the distribution system at least once each day. If the chlorine dioxide
residual in the water entering the distribution system exceeds the
MRDL contained in subsection (b)(3) of this section, the treatment
plant must conduct additional tests.
(A) If the public water system does not have additional
chlorination facilities in the distribution system, it must conduct
three additional tests at the service connection nearest the treatment
plant where an elevated chlorine dioxide residual was detected. The
first additional test must be conducted within two hours after detecting
an elevated chlorine dioxide residual at the entry point to the distribution
system. The two subsequent tests must be conducted at six-hour to
eight-hour intervals thereafter.
(B) If the public water system has additional chlorination
facilities in the distribution system, it must conduct an additional
test at the service connection nearest the treatment plant where an
elevated chlorine dioxide residual was detected, an additional test
at the first service connection after the point where the water is
rechlorinated, and an additional test at a location in the far reaches
of the distribution system. The additional test at the location nearest
the treatment plant must be conducted within two hours after detecting
an elevated chlorine dioxide residual at the entry point to the distribution
system. The two other tests must be conducted at six-hour to eight-hour
intervals thereafter.
(4) Public water systems shall monitor the disinfectant
residual at various locations throughout the distribution system.
(A) Public water systems that use groundwater or purchased
water sources only and serve fewer than 250 connections and fewer
than 750 people daily, must monitor the disinfectant residual at representative
locations in the distribution system at least once every seven days.
(B) Public water systems that serve at least 250 connections
or at least 750 people daily, and use only groundwater or purchased
water sources must monitor the disinfectant residual at representative
locations in the distribution system at least once per day.
(C) Public water systems using surface water sources
or groundwater under the direct influence of surface water must monitor
the disinfectant residual tests at least once per day at representative
locations in the distribution system.
(D) All public water systems must monitor the residual
disinfectant concentration each time that a bacteriological sample
is collected, as specified in §290.109 of this title (relating
to Microbial Contaminants).
(d) Analytical requirements. All monitoring required
by this section must be conducted at a facility approved by the executive
director and using methods that conform to the requirements of §290.119
of this title (relating to Analytical Procedures).
(1) The free chlorine or chloramine residual must be
measured to a minimum accuracy of plus or minus 0.1 mg/L. Samples
tested using a colorimetric method must be analyzed using a colorimeter;
spectrophotometer; or, with the written permission of the executive
director, a color comparator.
(2) The chlorine dioxide residual must be measured
to a minimum accuracy of plus or minus 0.05 mg/L using one of the
following methods:
(A) the amperometric titration method using a titrator
with platinum-platinum electrodes;
(B) the spectrophotometric Lissamine Green B method;
or
(C) with the written permission of the executive director,
the DPD-glycine method using a colorimeter or spectrophotometer.
(e) Reporting requirements. Any owner or operator of
a public water system subject to the provisions of this section is
required to report to the executive director the results of any test,
measurement, or analysis required by this section.
(1) Systems exceeding the MRDL for chlorine dioxide
in subsection (b)(3) of this section must report the exceedance to
the executive director within 24 hours of the event.
(2) Public water systems that use surface water sources
or groundwater sources under the direct influence of surface water
must submit a Surface Water Monthly Operating Report (commission Form
0102C) or a Surface Water Monthly Operating Report for 2-Filter Plants
(commission Form 0103) each month.
(3) Public water systems that use chlorine dioxide
must submit a Chlorine Dioxide Monthly Operating Report (commission
Form 0690) each month.
(4) Public water systems that use purchased water or
groundwater sources only must complete a Disinfection Level Quarterly
Operating Report (DLQOR, commission Form 20067) each quarter.
(A) Community and nontransient noncommunity public
water systems must submit the Disinfection Level Quarterly Operating
Report each quarter, by the tenth day of the month following the end
of the quarter.
(B) Transient noncommunity public water systems must
retain the Disinfection Level Quarterly Operating Reports and must
provide a copy if requested by the executive director.
(5) Monthly and quarterly reports required by this
section must be submitted to the Water Supply Division, MC 155, Texas
Commission on Environmental Quality, P.O. Box 13087, Austin, Texas
78711-3087 by the tenth day of the month following the end of the
reporting period.
(f) Compliance determinations. Compliance with the
requirements of this section shall be determined using the following
criteria.
(1) All samples used for compliance must be obtained
at sampling sites designated in the monitoring plan.
(A) All samples collected at sites designated in the
monitoring plan as microbiological and disinfectant residual monitoring
sites shall be included in the compliance determination calculations.
(B) Samples collected at sites in the distribution
system not designated in the monitoring plan shall not be included
in the compliance determination calculations.
(2) A public water system that fails to conduct the
monitoring tests required by this section commits a monitoring violation.
(3) A public water system that fails to report the
results of the monitoring tests required by this section commits a
reporting violation.
(4) A public water system that uses surface water sources
or groundwater sources under the direct influence of surface water
and fails to meet the requirements of subsection (b)(2) of this section
for a period longer than four consecutive hours commits a nonacute
treatment technique violation. A public water system that fails to
conduct the additional testing required by subsection (c)(1)(B)(iii)
of this section also commits a nonacute treatment technique violation.
(5) A public water system that uses chlorine dioxide
and exceeds the level specified in subsection (b)(3) of this section
violates the MRDL for chlorine dioxide.
(A) If a public water system violates the MRDL for
chlorine dioxide and any of the three additional distribution samples
exceeds the MRDL, the system commits an acute MRDL violation for chlorine
dioxide.
(B) If a public water system violates the MRDL for
chlorine dioxide and fails to collect each of the three additional
distribution samples required by subsection (c)(3) of this section,
the system commits an acute MRDL violation for chlorine dioxide.
(C) If a public water system violates the MRDL for
chlorine dioxide but none of the three additional distribution samples
violates the MRDL, the system commits a nonacute MRDL violation for
chlorine dioxide.
(6) A public water system that fails to meet the requirements
of subsection (b)(4) of this section, in more than 5.0% of the samples
collected each month, for any two consecutive months, commits a nonacute
treatment technique violation. Specifically, the system commits a
nonacute violation if the value "V" in the following formula exceeds
5.0% per month for any two consecutive months:
Attached Graphic
(7) A public water system violates the MRDL for chlorine
or chloramine if, at the end of any quarter, the running annual average
of monthly averages exceeds the level specified in subsection (b)(5)
of this section.
(8) Notwithstanding the MRDLs listed in subsection
(b) of this section, operators shall increase residual disinfectant
levels of chlorine or chloramines (but not chlorine dioxide) in the
distribution system to a level and for a time necessary to protect
public health to address specific microbiological contamination problems
caused by circumstances such as distribution line breaks, storm runoff
events, source water contamination, or cross-connections.
(9) If a public water system's failure to monitor makes
it impossible to determine compliance with the MRDL for chlorine or
chloramines, the system commits an MRDL violation for the entire period
covered by the annual average.
Cont'd... |
