EXHIBIT 5.1


                        [GOODWIN PROCTER LLP LETTERHEAD]


                                  June 3, 2003



Watts Industries, Inc.
815 Chestnut Street
North Andover, Massachusetts  01845

      Re:   Legality of Securities to be Registered Under Registration Statement
            on Form S-8

Ladies and Gentlemen:

      This opinion is furnished in connection with the registration statement on
Form S-8 (the "Registration Statement") pursuant to the Securities Act of 1933,
as amended (the "Securities Act"), relating to the registration of the sale of
up to an aggregate of 85,000 shares (the "Shares") of class A common stock, par
value $0.10 per share, of Watts Industries, Inc., a Delaware corporation (the
"Company"), which may be issued under the Watts Industries, Inc. 2003
Non-Employee Director Stock Option Plan.

      In connection with rendering this opinion, we have examined (i) the
Restated Certificate of Incorporation of the Company, as amended, as on file
with the Secretary of State of the State of Delaware, (ii) the Amended and
Restated By-laws of the Company, as amended, (iii) such records of the corporate
proceedings of the Company as we deemed material, (iv) the Registration
Statement and the exhibits thereto, and (v) such other certificates, receipts,
records and documents as we considered necessary for the purposes of this
opinion. In our examination, we have assumed the genuineness of all signatures,
the legal capacity of natural persons, the authenticity of all documents
submitted to us as certified, photostatic or facsimile copies, the authenticity
of the originals of such copies and the authenticity of telephonic confirmations
of public officials and others. As to facts material to our opinion, we have
relied upon certificates or telephonic confirmations of public officials and
certificates, documents, statements and other information of the Company or
representatives or officers thereof.

      We are attorneys admitted to practice in The Commonwealth of
Massachusetts. We express no opinion concerning the laws of any jurisdictions
other than the laws of the United States of America and The Commonwealth of
Massachusetts and the Delaware General Corporation Law (which includes
applicable provisions of the Delaware General Corporation Law and reported
judicial decisions interpreting the Delaware General Corporation Law and
applicable provisions of the Delaware Constitution), and also express no opinion
with respect to the blue sky or securities laws of any state, including
Massachusetts and Delaware.


Watts Industries, Inc.
June 3, 2003
Page 2


      Based upon the foregoing, we are of the opinion that upon the issuance and
delivery of the Shares against payment therefor in accordance with the terms of
the Plan, the Shares will be validly issued, fully paid and nonassessable under
the Delaware General Corporation Law.

      The foregoing assumes that all requisite steps will be taken to comply
with the requirements of the Securities Act and applicable requirements of state
laws regulating the offer and sale of securities.

      We hereby consent to the inclusion of this opinion as an exhibit to the
Registration Statement. In giving such consent, we do not thereby admit that we
are in the category of persons whose consent is required under Section 7 of the
Securities Act, or the rules and regulations thereunder.

                                          Sincerely,

                                          /S/ GOODWIN PROCTER  LLP

                                          GOODWIN PROCTER  LLP