Illinois Administrative Code › Title 35 - ENVIRONMENTAL PROTECTION › Part 611 - PRIMARY DRINKING WATER STANDARDS › Subpart L - MICROBIOLOGICAL MONITORING AND ANALYTICAL REQUIREMENTS › Section 611.532 - Unfiltered PWSs

Current through Register Vol. 48, No. 28, July 12, 2024
If the Agency determines that filtration is required, it must
				  specify alternative monitoring requirements, as appropriate, until filtration
				  is in place. A supplier using a groundwater source under the direct influence
				  of surface water not providing filtration treatment must monitor as the Agency
				  directs in a SEP after determining under Section
				  611.212 that the supplier's
				  groundwater source is under the direct influence of surface water, requiring
				  the supplier to install and apply filtration treatment, and specifying
				  appropriate monitoring requirements until filtration is in place.
a) The supplier must sample and analyze for
				fecal coliform or total coliform as Section
				611.231(a)
				requires on representative source water samples it collects immediately prior
				to the first or only point of applying disinfectant. The supplier must sample
				for fecal or total coliforms no less frequently than Table B specifies each
				week the supplier serves water to the public. The supplier must also sample and
				analyze once for fecal or total coliform density every day the supplier serves
				water to the public and the turbidity of its source water exceeds 1 NTU (these
				samples count towards the weekly coliform sampling requirement), unless the
				Agency issues a SEP determining that the supplier cannot analyze within 30
				hours after collecting the sample for logistical reasons outside the supplier's
				control.
b) The supplier must
				measure turbidity as Section
				611.231(b)
				requires on representative grab samples of source water it collects immediately
				prior to the first or only point of applying disinfectant no less frequently
				than every four hours when the supplier serves water to the public. A supplier
				may substitute continuous turbidity monitoring for grab sample monitoring after
				validating the accuracy of regular the continuous measurement for accuracy
				using a protocol the Agency approved in a SEP.
c) The supplier must determine its total
				inactivation ratio for each day it operates based on the appropriate
				CT99.9
									 values in
				Appendix B. The supplier must monitor the parameters necessary to determine its
				total inactivation ratio using specific procedures:
1) The supplier must measure temperature of
				the disinfected water at least once per day at each RDC sampling
				point.
2) If using chlorine, the
				supplier must measure the pH of the disinfected water at least once per day at
				each chlorine RDC sampling point.
3) The supplier must determine the
				disinfectant contact times ("T") for each day during peak hourly
				flow.
4) The supplier must measure
				the RDCs ("C") of the water before or at the first customer each day during
				peak hourly flow.
5) A supplier
				using a disinfectant other than chlorine may monitor by other Agency-approved
				methods under Section
				611.241(a).