| (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.
All 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 (measured as
total chlorine).
(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 (measured as total chlorine).
(5) The running annual average of the free chlorine
or chloramine residual (measured as total chlorine) of the water within
the distribution system shall not exceed an MRDL of 4.0 mg/L.
(c) Monitoring requirements. All 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) Entry point compliance monitoring for surface water
and groundwater under the direct influence of surface water. 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 at each
entry point. 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 at
each entry point 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.
(C) Continuous monitors must record the disinfectant
residual of the water every 30 minutes.
(2) Entry point compliance monitoring for groundwater
and purchased water. 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.
(A) A public water system that uses free chlorine must
measure free chlorine.
(B) A public water system that has a chloramine residual
must measure total chlorine.
(3) Chlorine dioxide compliance monitoring. 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) Distribution system compliance monitoring. All
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 at the same time and at the same sampling
site a bacteriological sample is collected, as specified in §290.109
of this title (relating to Microbial Contaminants) in addition to
the residual disinfectant concentration monitoring requirements as
described in this subsection and chapter.
(E) All public water systems with a chloramine residual
must monitor the total chlorine residual downstream of any chlorine
and ammonia injection points, in conjunction with the chloramine effectiveness
sampling in paragraph (5)(C) of this subsection, in the distribution
system weekly and whenever the chemical dose is changed.
(5) Chloramine effectiveness sampling. Public water
systems with a chloramine residual shall monitor to ensure that monochloramine
is the prevailing chloramine species and that nitrification is controlled.
Sample sites and procedures used for chloramine effectiveness sampling
must be documented in the system's nitrification action plan (NAP)
required by §290.46(z) of this title (relating to Minimum Acceptable
Operating Practices for Public Drinking Water Systems). Sample results
determined by monitoring required under this paragraph will not be
used to determine compliance with the maximum contaminant levels,
MRDLs, action levels, or treatment techniques of this subchapter.
Cont'd... |
