12. Nitrate 10 mg/l (as Nitrogen)
(see Note 4 below)
13. Nitrite 1 mg/L (as Nitrogen)
14. Total Nitrate and Nitrite 10 mg/L (as Nitrogen)
15. Selenium 0.05 mg/L
16. Sodium --- (see Note 1 below)
17. Sulfate 1000 mg/L (see Note 2 below)
18. Thallium 0.002 mg/L
19. Total Dissolved Solids 2000 mg/L (see Note 3 below)
NOTE:
(1) No maximum contaminant level has been established for
nickel and sodium. However, these contaminant shall be monitored
and reported in accordance with the requirements of R309-205-5(3).
(2) If the sulfate level of a public (community, NTNC and
non-community) water system is greater than 500 mg/L, the supplier
shall satisfactorily demonstrate that:
(a) No better quality water is available, and
(b) The water shall not be available for human consumption
from commercial establishments.
In no case shall the Director allow the use of water having a
sulfate level greater than 1000 mg/L.
(3) If TDS is greater than 1000 mg/L, the supplier shall
satisfactorily demonstrate to the Director that no better water
is available. The Director shall not allow the use of an inferior
source of water if a better source of water (i.e. lower in TDS)
is available.
(4) In the case of a non-community water systems which
exceed the MCL for nitrate, the Director may allow,
on a case-by-case basis, a nitrate level not to exceed 20 mg/L if
the supplier can adequately demonstrate that:
(a) such water will not be available to children under 6
months of age as may be the case in hospitals, schools and day
care centers; and
(b) there will be continuous posting of the fact that nitrate
levels exceed 10 mg/L and the potential health effect of exposure
in accordance with R309-220-12; and
(c) the water is analyzed in conformance to
R309-205-5(4); and
(d) that no adverse health effects will result.
(5) The maximum contaminant level for arsenic is 0.05 mg/L
until January 23, 2006. The MCL of 0.010 mg/L is effective for the
purposes of compliance on January 23, 2006.
(2) Lead and copper.
(a) The lead action level is exceeded if the concentration of lead in more than 10 percent of tap water samples collected during any monitoring period conducted in accordance with R309-210-6(3) is greater than 0.015 mg/L (i.e., if the "90th percentile" lead level is greater than 0.015 mg/L).
(b) The copper action level is exceeded if the concentration of copper in more than 10 percent of tap water samples collected during any monitoring period conducted in accordance with R309-210-6(3) is greater than 1.3 mg/L (i.e., if the "90th percentile" copper level is greater than 1.3 mg/L).
(c) The 90th percentile lead and copper levels shall be computed as follows:
(i) The results of all lead or copper samples taken during a monitoring period shall be placed in ascending order from the sample with the lowest concentration to the sample with the highest concentration. Each sampling result shall be assigned a number, ascending by single integers beginning with the number 1 for the sample with the lowest contaminant level. The number assigned to the sample with the highest contaminant level shall be equal to the total number of samples taken.
(ii) The number of samples taken during the monitoring period shall be multiplied by 0.9.
(iii) The contaminant concentration in the numbered sample yielded by the calculation in paragraph (c)(ii) above is the 90th percentile contaminant level.
(iv) For water systems serving fewer than 100 people that collect 5 samples per monitoring period, the 90th percentile is computed by taking the average of the highest and second highest concentrations.
(v) For a public water system that has been allowed by the Director to collect fewer than five samples in accordance with R309-210-6(3)(c), the sample result with the highest concentration is considered the 90th percentile value.
(3) Organic Contaminants.
The following are the maximum contaminant levels for organic chemicals. For the purposes of R309-100 through R309-R309-605, organic chemicals are divided into three categories: Pesticides/PCBs/SOCs, volatile organic contaminants (VOCs) and total trihalomethanes.
(a) Pesticides/PCBs/SOCs - The MCLs for organic contaminants listed in Table 200-2 are applicable to community water systems and non-transient, non-community water systems.
TABLE 200-2
PESTICIDE/PCB/SOC CONTAMINANTS