Company: MSEX
Filing Date: 2025-07-29
Form Type: 424B5
Source: 0001104659-25-071727
Chunk: 0

Company: MIDDLESEX WATER CO
Filing Date: 2025-07-29
Form: 424B5
Chunk 0
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Filed Pursuant to Rule 424(b)(5)

Registration Statement No. 333-287177

PROSPECTUS SUPPLEMENT(To Prospectus Dated May 12, 2025)

<div align='center'>712,353 Shares

Middlesex Water Company
Investment Plan

A Direct Share Purchase and Sale and Dividend Reinvestment Plan for
Middlesex Water Company Common Stock, no Par Value</div>

This prospectus supplement
relates to shares of common stock, no par value (“Middlesex Common Stock”), of Middlesex Water Company (“Middlesex”
or the “Company”) that we may offer and sell from time to time according to the terms of the Middlesex Water Company Investment
Plan (the “Plan”). Middlesex filed a Registration Statement on Form S-3 (File No. 333-266482) on August 3, 2022, which was supplemented with prospectus supplements filed on August 3, 2022 and July 25, 2023, which registering or sale
pursuant to the Plan 911,201 shares of Middlesex Common Stock (such shares, the “Previously Registered Shares”). As of the
date hereof, 712,353 of the Previously Registered Shares remain unsold (such unsold Previously Registered Shares, the “Remaining
Shares”). This prospectus supplement is being filed to continue the offering of the Remaining Shares under Middlesex’s Registration
Statement on Form S-3 (File No. 333-287177) filed on May 12, 2025 (the “Form S-3”). This supplement should
be read in conjunction with the base prospectus included in the Form S-3 and any other filings incorporated therein or herein by
reference.

Middlesex is offering up
to 712,353 shares of Middlesex Common Stock under the Plan, a direct share purchase, sale and dividend reinvestment plan that is designed
to provide investors with a convenient method to purchase shares of Middlesex Common Stock and to reinvest cash dividends in the purchase
of additional shares. First time investors and existing registered shareholders who hold freely tradable shares of Middlesex Common Stock
can submit requests to buy shares of Middlesex Common Stock without opening up a brokerage account. Although the Plan contemplates the
continued payment of quarterly dividends, the Company can make no assurances in that regard.

Middlesex Common Stock is
listed on the NASDAQ Global Select Market under the symbol “MSEX.” On July 28, 2025 the