Second Quarter/YTD 2023 Results

Revenue Growth and Customer Growth Help Drive Operating Cost Efficiency AMERICAN WATER 46.1% 41.0% 39.1% Regulated O&M Efficiency Ratio* 36.6% 35.6% 34.3% 34.1% 33.7% < 30.0% ** 2010 2012 2014 2016 2018 2020 2021 2022 2027 Target • Efficiency Drivers: Growing Revenues & Controlling Costs In early years (thru 2016), efficiency gains were steeper as culture of cost management formed Recently, more incremental efficiency gains driven by revenue growth, cost management and technology * Non-GAAP Measure - O&M Efficiency Ratio = Adjusted Regulated O&M Expenses (O&M Expenses is most comparable GAAP measure) / Adjusted Regulated Operating Revenues (Operating Revenues is most comparable GAAP measure). This calculation assumes purchased water revenues approximate purchased water expenses. ** A reconciliation to a most comparable forward-looking GAAP measure is not available without unreasonable effort 13

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