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C A RY, N O RT H C A R O L I N A A N N U A L WAT E R Q U A L I T Y R E P O R T 2 0 2 3 8 D R I N K I N G WAT E R T E ST R E S U L T S M I C R O B I O LO G I C A L C O N TA M I N A N T S Each month, Cary tests for Total Coliform and E. coli bacteria from approximately 137 different sample points from throughout the service area. In 2023, we had a Total Coliform-positive repeat sample following an E. coli-positive routine sample from a single sample site. For more information, see page 12. SUBSTANCE (UNIT OF MEASURE) YEAR SAMPLED HIGHEST LEVEL ALLOWED (MCL) HIGHEST LEVEL GOAL (MCLG) AMOUNT DETECTED VIOLATION TYPICAL SOURCE Total Coliform Bacteria (presence or absence) 2023 TT* N/A N/A N/A Naturally present in the environment E. coli (presence or absence) 2023 Routine and repeat samples are total coliform- positive and either is E. coli-positive or system fails to take repeat samples following E. coli- positive routine sample or system fails to analyze total coliform-positive repeat sample for E. coli Note: If either an original routine sample and/or its repeat samples(s) are E. coli positive, a Tier 1 violation exists. 0 1 Yes Human and animal fecal waste *If a system collecting 40 or more samples per month finds greater than 5% of monthly samples are positive in one month, an assessment is required. T U R B I D I T Y Turbidity is a measure of the clarity of the water. We monitor it because it is a good indicator of the effectiveness of our filtration system. The turbidity rule requires that 95% or more of our monthly samples must be less than or equal to 0.3 NTU. Our water meets this requirement. SUBSTANCE (UNIT OF MEASURE) YEAR SAMPLED HIGHEST LEVEL ALLOWED (MCL) HIGHEST LEVEL GOAL (MCLG) AMOUNT DETECTED RANGE VIOLATION TYPICAL SOURCE Turbidity (NTU) 2023 TT = 1 NTU and 95% of samples < 0.3 NTU N/A 0.09 NTU AND 100% of samples < 0.3 NTU 0.03–0.09 No Soil runoff One of the 137 biological samples collected from Cary's distribution system each month.

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