Current through September 17, 2024
A public water system that uses a surface water source must
provide treatment consisting of both disinfection, as specified in 179 NAC
13-005.02 and filtration treatment
which complies with the requirements of 179 NAC 13-006.01 to 13-006.04 by June
29, 1993. A public water system that uses a ground source which is under the
direct influence of surface water and does not meet all the criteria in 179 NAC
13-004 for avoiding filtration, must
provide treatment consisting of both disinfection, as specified in 179 NAC
13-005.02 and filtration which
complies with the requirements of 179 NAC 13-006.01 to 13-006.04 within 18
months of the failure to meet any one of the criteria for avoiding filtration
in 179 NAC
13-004. Failure to meet any
requirement of 179 NAC 13-006 is a treatment technique violation.
006.01 Conventional Filtration Treatment or
Direct Filtration
13-006.01A For systems
using conventional filtration or direct filtration, the turbidity level of
representative samples of a system's filtered water must be less than or equal
to 0.5 NTU in at least 95% of the measurements taken each month, measured as
specified in 179 NAC
13-007.01A and
13-007.03A,
except that if the Director determines that the system is capable of achieving
at least 99.9% removal and/or inactivation of Giardia lamblia
cysts at some turbidity level higher than 0.5 NTU in at least 95% of
the measurements taken each month, the Director may substitute this higher
turbidity limit for that system. However, in no case may the Director approve a
turbidity limit that allows more than 1 NTU in more than 5% of the samples
taken each month, measured as specified in 179 NAC
13-007.01A and
13-007.03A.
13-006.01B The turbidity level of
representative samples of a system's filtered water must at no time exceed 5
NTU, measured as specified in 179 NAC
13-007.01A and
13-007.03A.
13-006.01C Beginning January 1, 2002, systems
serving at least 10,000 people must meet the turbidity requirements in 179 NAC
17-006.01.
13-006.01D Beginning
January 14, 2005, systems serving fewer than 10,000 people must meet the
turbidity requirements in 179 NAC 19-009.01 through 19-009.04.
006.02 Slow Sand Filtration
13-006.02A For systems using slow sand
filtration, the turbidity level of representative samples of a system's
filtered water must be less than or equal to 1 NTU in at least 95% of the
measurements taken each month, measured as specified in 179 NAC
13-007.01A and
13-007.03A,
except that if the Director determines there is no significant interference
with disinfection at a higher turbidity level, the Director may substitute this
higher turbidity limit for that system.
13-006.02B The turbidity level of
representative samples of a system's filtered water must at no time exceed 5
NTU, measured as specified in 179 NAC
13-007.01A and
13-007.03A.
006.03 Diatomaceous Earth
Filtration
13-006.03A For systems using
diatomaceous earth filtration, the turbidity level of representative samples of
a system's filtered water must be less than or equal to 1 NTU in at least 95%
of the measurements taken each month, measured as specified in 179 NAC
13-007.01A and
13-007.03A.
13-006.03B The turbidity level of
representative samples of a system's filtered water must at no time exceed 5
NTU, measured as specified in 179 NAC
13-007.01A to
13-007.03A.
006.04 Other Filtration
Technologies
: A public water system may use a filtration technology not
listed in 179 NAC 13-006.01 to 13-006.03 if it demonstrates to the Director
using pilot plant studies or other means, that the alternative filtration
technology, in combination with disinfection treatment that meets the
requirements of 179 NAC
13-005.02, consistently achieves
99.9% removal and/or inactivation of Giardia lamblia cysts and
99.99% removal and/or inactivation of viruses. For a system that makes this
demonstration, the requirements of 179 NAC 13-006.02 apply. Beginning January
1, 2002, systems serving at least 10,000 people must meet the requirements for
other filtration technologies in 179 NAC 17-005.02. Beginning January 14, 2005,
systems serving fewer than 10,000 people must meet the requirements for other
filtration technologies in 179 NAC 19-009.01 through
19-009.04.
