Amendment, dated December 6, 2018, to Letter Agreement between Michael A. Sgro and American Water Works Company, Inc

You shall be eligible to participate in the Company’s Long-Term Performance Plan (“LTPP”), as it may be established or maintained from time to time. Your 2019 aggregate LTPP award opportunity is targeted to be 125% of your Base Salary for the 2019 calendar year, and is subject to increase or decrease as determined thereafter by the Executive Development and Compensation Committee of American Water’s Board of Directors (the “Committee”). The terms of any LTPP awards, if and when granted to you by the Committee, shall be governed by and subject to all of the terms and conditions of the Company’s 2017 Omnibus Equity Compensation Plan (the “Omnibus Plan”), as it may be amended from time to time, and the relevant LTPP plan documents and applicable LTPP award documents or agreements, and the Company shall recommend your LTPP awards to be considered for approval each year by the Committee to include terms and conditions consistent with those described in this letter. Subject in each case to approval and grant by the Committee, you will be eligible to receive grants of equity-based awards under the LTPP, subject in all respects to the terms of the Omnibus Plan and applicable award documents or agreements, with the following special vesting terms: (i) 2020 grants will vest 1/3rd on January 31, 2021 and 2/3rds on January 31, 2022; and (ii) 2021 grants will vest in full on January 31, 2022; provided, that, in each case, any grants subject to performance-based vesting shall be subject to distribution and payment based on the determination by the Committee of actual performance achieved following the completion of the applicable performance period for each such award.