Illinois Administrative Code
Title 35 - ENVIRONMENTAL PROTECTION
Part 611 - PRIMARY DRINKING WATER STANDARDS
Subpart L - MICROBIOLOGICAL MONITORING AND ANALYTICAL REQUIREMENTS
Section 611.533 - Filtered PWSs
Current through Register Vol. 48, No. 38, September 20, 2024
A supplier using a surface water source or a groundwater source under the direct influence of surface water and providing filtration treatment must monitor in accordance with this Section.
a) The supplier must perform turbidity measurements Section 611.250 requires on representative samples of the PWS's filtered water every four hours (or more frequently) when the supplier serves water to the public. A supplier may substitute continuous turbidity monitoring for grab sample monitoring if it validates the continuous measurement for accuracy on a regular basis using a protocol the Agency approved in a SEP. For a supplier using slow sand filtration or filtration treatment other than conventional treatment, direct filtration, or diatomaceous earth filtration, the Agency must reduce the sampling frequency to once per day in a SEP if the Agency determines that less frequent monitoring is sufficient to indicate effective filtration performance. For a supplier serving 500 or fewer persons, the Agency must reduce the turbidity sampling frequency to once per day in a SEP if the Agency determines that less frequent monitoring is sufficient to indicate effective filtration performance regardless of the type of filtration treatment used.
b) RDC Entering Distribution System
c) Points of Measurement
BOARD NOTE: This Section derives from 40 CFR 141.74(c).