Executive Change

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 26, 2026 MIDDLESEX WATER COMPANY (Exact Name of Registrant as Specified in Charter) New Jersey 0-422 22-1114430 (State or other jurisdiction of incorporation or organization) (Commission File Number) (I.R.S. Employer Identification No.) 485C Route 1 South , Suite 400 , Iselin , New Jersey 08830 (Address of Principal Executive Offices, and Zip Code) 732 - 634-1500 Registrant’s Telephone Number, Including Area Code Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below): o     Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) o     Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) o     Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) o     Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each class Trading Symbol(s) Name of each exchange on which registered Common Stock, No Par Value MSEX The Nasdaq Stock Market, LLC Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company o If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Ac t. o Item 5.02 DEPARTURE OF DIRECTORS OR PRINCIPAL OFFICERS; ELECTION OF DIRECTORS; APPOINTMENT OF PRINCIPAL OFFICERS On March 26, 2026, Middlesex Water Company announced the appointment of Tatyana Kaplan as Vice President and Chief Accounting Officer, effective March 26, 2026, as per the attached release. Middlesex Water Company also announced the departure of Robert J. Capko as Principal Accounting Officer, effective March 26, 2026, with Mr. Capko remaining an employee of the Company as the Corporate Controller. Press Release Middlesex Water Company has announced the appointment of Tatyana Kaplan as Vice President and Chief Accounting Officer, effective March 26, 2026. A copy of the Company’s press release dated March 26, 2026, is filed herewith as Exhibit 99.1 and is hereby incorporated by reference. Middlesex Water Company has announced the departure of Robert J. Capko as Principal Accounting Officer, effective March 26, 2026 with Mr. Capko remaining an employee of the Company as the Corporate Controller. A copy of the Company’s press release dated March 26, 2026, is filed herewith as Exhibit 99.1 and is hereby incorporated by reference.. Item 9.01 Financial Statements and Exhibits Exhibit Number Description of Document 99.1 Press Release, dated March 26, 2026. 99.2 Change in Control Agreement between Middlesex Water Company and Tatyana Kaplan. SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. MIDDLESEX WATER COMPANY By: /s/ Jay L. Kooper       Jay L. Kooper      Vice President, General Counsel and Secretary Date: March 26, 2026