Current through August 26, 2024
Section
NR
811.42 requires filtration for all surface water
sources. The following applies only to GWUDI systems not required to
filter.
(1) DETERMINATION OF MEAN
CRYPTOSPORIDIUM LEVEL.
(a) Following
completion of the initial source water monitoring required under s.
NR 809.331(1), water suppliers for
unfiltered systems shall calculate the arithmetic mean of all Cryptosporidium
sample concentrations reported under s.
NR 809.331(1). Water suppliers shall
report this value to the department for approval no later than 6 months after
the month the system is required to complete initial source water monitoring
based on the schedule in s.
NR 809.331(3).
(b) Following completion of the second round
of source water monitoring required under s.
NR 809.331(2), water suppliers for
unfiltered systems shall calculate the arithmetic mean of all Cryptosporidium
sample concentrations reported under s.
NR 809.331(2). Water suppliers shall
report this value to the department for approval no later than 6 months after
the month the system is required to complete the second round of source water
monitoring based on the schedule in s.
NR 809.331(3).
(c) If the monthly Cryptosporidium sampling
frequency varies, water suppliers shall first calculate a monthly average for
each month of monitoring. Systems shall then use these monthly average
concentrations, rather than individual sample concentrations, in the
calculation of the mean Cryptosporidium level in par. (a) or (b).
(d) The report to the department of the mean
Cryptosporidium levels calculated under pars. (a) and (b) shall include a
summary of the source water monitoring data used for the calculation.
(e) Failure to comply with the
conditions of this subsection is a violation of the treatment technique
requirement.
(2)
CRYPTOSPORIDIUM INACTIVATION REQUIREMENTS. Unfiltered systems shall provide the
level of inactivation for Cryptosporidium specified in this subsection, based
on their mean Cryptosporidium levels as determined under sub. (1) and according
to the schedule in s.
NR 810.37.
(a)
Unfiltered systems with a mean Cryptosporidium level of 0.01 oocysts/L or less
shall provide at least 2-log Cryptosporidium inactivation.
(b) Unfiltered systems with a mean
Cryptosporidium level of greater than 0.01 oocysts/L shall provide at least
3-log Cryptosporidium inactivation.
(3) INACTIVATION TREATMENT TECHNOLOGY
REQUIREMENTS. Unfiltered systems shall use chlorine dioxide, ozone, or UV as
described in s.
NR 810.46 to meet the Cryptosporidium inactivation
requirements of this section.
(a) Unfiltered
systems that use chlorine dioxide or ozone and fail to achieve the
Cryptosporidium inactivation required in sub. (2) on more than one day in the
calendar month are in violation of the treatment technique
requirement.
(b) Unfiltered systems
that use UV light and fail to achieve the Cryptosporidium inactivation required
in sub. (2) by meeting the criteria in s.
NR 810.46 are inviolation of the treatment technique
requirement.
(4) USE OF
TWO DISINFECTANTS. Unfiltered systems shall use a minimum of 2 disinfectants to
meet the combined Cryptosporidium inactivation requirements of this section
along with the Giardia lamblia and virus inactivation requirements of s.
NR 810.31(1). Each of the 2
disinfectants shall separately achieve the total inactivation required for
either Cryptosporidium, Giardia lamblia, or viruses.
