Company: MSEX
Filing Date: 2025-07-29
Form Type: 424B5
Source: 0001104659-25-071727
Chunk: 1

Company: MIDDLESEX WATER CO
Filing Date: 2025-07-29
Form: 424B5
Chunk 1
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 closing price of Middlesex Common
Stock on the NASDAQ Global Select Market was $51.52 per share.

Investing in Middlesex Common
Stock involves risks. Before making a decision to invest in Middlesex Common Stock, you should carefully consider the risks described
in Part I, Item 1A of the Company’s most recent Annual Report on Form 10-K (“Form 10-K”) under
the heading “Risk Factors,” Part II, Item 1A of the Company’s most recent Quarterly Report on Form 10-Q
(“Form 10-Q”) under the heading “Risk Factors,” and under the headings “Risk Factors” of this
prospectus supplement and the accompanying prospectus. The Form 10-K and Form 10-Q are incorporated by reference in this prospectus
supplement and the accompanying prospectus.

Neither the Securities and Exchange Commission (“SEC”) nor any other regulatory body has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement or the related prospectus. Any representation to the contrary is a criminal offense.

No person has been authorized to give any information or to make any representations other than those contained in this prospectus supplement. If any other information or representations are given or made, you must not rely on them as having been authorized.

<div align='center'>This Prospectus Supplement is dated July 29,
2025

TABLE OF CONTENTS

Prospectus Supplement</div>

|                                                           | Page |
| ABOUT THIS PROSPECTUS SUPPLEMENT                          | S-i  |
| SUMMARY                                                   | S-1  |
| RISK FACTORS                                              | S-2  |
| MIDDLESEX WATER COMPANY                                   | S-3  |
| CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS | S-5  |
| INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE           | S-7  |
| THE MIDDLESEX WATER COMPANY INVESTMENT PLAN               | S-9  |
| PURPOSE                                                   | S-9  |
| PLAN ADVANTAGES                                           | S-9  |
| ADMINISTRATION                                            | S-10 |
| ELIGIBILITY AND ENROLLMENT                                | S-11 |
| OPTIONAL CASH INVESTMENTS                                 | S-13 |
| PURCHASE OF COMMON STOCK                                  | S-16 |
| DIVIDEND REINVESTMENT                                     | S-17 |
| GIFTS AND TRANSFERS OF SHARES                             | S-19 |
| SALE OF