TITLE 35: ENVIRONMENTAL PROTECTION
SUBTITLE F: PUBLIC WATER SUPPLIES
CHAPTER I: POLLUTION CONTROL BOARD
PART 611 PRIMARY DRINKING WATER STANDARDS
SECTION 611.560 TURBIDITY
Section 611.560 Turbidity
The requirements in this Section apply to unfiltered PWSs until filtration is installed.
a) Suppliers must take samples at representative entry points to the distribution system at least once per day, for the purposes of making turbidity measurements to determine compliance with Section 611.320.
1) If Public Health determines that a reduced sampling frequency in a non-CWS will not pose a risk to public health, it may reduce the required sampling frequency. The option of reducing the turbidity frequency will be permitted only in those suppliers that practice disinfection and which maintain an active RDC in the distribution system, and in those cases where Public Health has indicated in writing that no unreasonable risk to health existed under the circumstances of this option.
2) The turbidity measurements must be made in accordance with one of the methods set forth in Section 611.531(a).
b) If the result of a turbidity analysis indicates that the maximum allowable limit has been exceeded, the sampling and measurement must be confirmed by resampling as soon as practicable and preferably within one hour. If the repeat sample confirms that the maximum allowable limit has been exceeded, the supplier of water must report to the Agency within 48 hours. The repeat sample must be the sample used for the purpose of calculating the monthly average. If the monthly average of the daily samples exceeds the maximum allowable limit, or if the average of two samples taken on consecutive days exceeds 5 NTU, the supplier of water must report to the Agency and notify the public as directed in Subpart V of this Part.
c) This subsection (c) corresponds with 40 CFR 141.22(c), which states a past effective date for CWSs.
d) This Section applies only to suppliers that use water obtained in whole or in part from surface sources.
BOARD NOTE: Derived from 40 CFR 141.22 (2002).
(Source: Amended at 27 Ill. Reg. 16447, effective October 10, 2003)