Current through March 20, 2024
014.01
Determination of Mean Cryptosporidium Level
25-014.01A Following completion of the source
water monitoring, unfiltered systems must calculate the arithmetic mean of all
Cryptosporidium sample concentrations. Systems must report
this value to the Department for approval no later than six months after the
month the system is required to complete source water monitoring.
25-014.01B If the monthly
Cryptosporidium sampling frequency varies, systems must first
calculate a monthly average for each month of monitoring. Systems must then use
these monthly average concentrations, rather than individual sample
concentrations, in the calculation of the mean Cryptosporidium
level.
25-014.01C The
report to the Department of the mean Cryptosporidium levels
must include a summary of the source water monitoring data used for the
calculation.
25-014.01D Failure to
comply with the conditions of 179 NAC 25-014.01 is a violation of the treatment
technique requirement.
014.02 Cryptosporidium Inactivation
Requirements
Unfiltered systems must provide the level of inactivation for
Cryptosporidium specified in this paragraph, based on their
mean Cryptosporidium levels and according to the schedule for
compliance.
25-014.02A Unfiltered
systems with a mean Cryptosporidium level of 0.01 oocysts/L or
less must provide at least 2-log Cryptosporidium
inactivation.
25-014.02B
Unfiltered systems with a mean Cryptosporidium level of
greater than 0.01 oocysts/L must provide at least 3-log Cryptosporidium
inactivation.
014.03 Inactivation Treatment Technology
Requirements
Unfiltered systems must use chlorine dioxide, ozone, or UV to
meet the Cryptosporidium inactivation requirements.
25-014.03A Systems that use chlorine dioxide
or ozone and fail to achieve the required Cryptosporidium
inactivation on more than one day in the calendar month are in
violation of the treatment technique requirement.
25-014.03B Systems that use UV light and fail
to achieve the required Cryptosporidium inactivation by
meeting the criteria in 179 NAC
25-022.04C2 are
in violation of the treatment technique requirement.
014.04 Use of Two Disinfectants
Unfiltered systems must meet the combined
Cryptosporidium inactivation requirements of this section and
Giardia lamblia and virus inactivation requirements of 179 NAC
13-005.01 using a minimum of two disinfectants, and each of two disinfectants
must separately achieve the total inactivation required for either
Cryptosporidium, Giardia lamblia, or
viruses.
