Company Update

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: May 15, 2023   MIDDLESEX WATER COMPANY (Exact name of registrant as specified in its charter)   New Jersey 0-422 22-1114430 (State or other jurisdiction of (Commission (I.R.S. Employer incorporation or organization) File Number) Identification No.)   485C Route 1 South , Suite 400 , Iselin , New Jersey 08830 (Address of Principal Executive Offices) (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: ☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)   ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)   ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))   ☐ 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 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 ☐ 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 Act. ☐       Item. 8.01. Other Events   Announcement regarding Middlesex Water Company filing for a base rate adjustment, and two additional filings which include a plan to recoup Lead Service Line replacement costs and a Foundational Filing to implement a Distribution System Improvement Charge, as set forth in the attached press release.   Item 9.01 – (d) Exhibits Press release dated May 15, 2023 announcing that Middlesex Water Company filed a petition with the New Jersey Board of Public Utilities seeking to increase water rates charged to customers .         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 of the undersigned hereunto duly authorized.         MIDDLESEX WATER COMPANY                       (Registrant)                       /s/A. Bruce O’Connor   A. Bruce O’Connor   Senior Vice President, Treasurer and   Chief Financial Officer     Dated: May 15, 2023   2