EXHIBIT 5

                        [L&W ISSUING OFFICE LETTERHEAD]

                                 July 6, 2001


Southwest Water Company
225 North Barranca Avenue, Suite 200
West Covina, California 91791-1605

          Re:  Registration Statement No. 333-63196; $16,000,000 Aggregate
               Offering Price of Convertible Subordinate Debentures of Southwest
               Water Company

Ladies and Gentlemen:

          In connection with the registration of $16,000,000 aggregate principal
amount of Convertible Subordinate Debentures due July 1, 2021 (the
"Securities"), by Southwest Water Company, a Delaware corporation (the
"Company"), under the Securities Act of 1933, as amended (the "Securities Act"),
on Form S-3 filed with the Securities and Exchange Commission (the
"Commission"), on June 15, 2001 (File No. 333-63196), as amended by Amendment
No. 1, expected to be filed on July 6, 2001 (collectively, the "Registration
Statement"), you have requested our opinion with respect to the matters set
forth below.

          You have provided us with the prospectus (the "Prospectus") which is
part of the Registration Statement.  The Securities will be issued pursuant to
an indenture between the Company and Chase Manhattan Bank and Trust Company,
National Association as trustee (the "Trustee") in the form attached as Exhibit
4 to the Registration Statement, (the "Indenture").  The Securities will be
convertible into shares of common stock, par value $0.01 per share, of the
Company (the "Common Stock").

          In our capacity as your counsel in connection with such registration,
we are familiar with the proceedings taken and proposed to be taken by the
Company in connection with the authorization and issuance of the Securities, and
for the purposes of this opinion, have assumed such proceedings will be timely
completed in the manner presently proposed. In addition, we have made such legal
and factual examinations and inquiries, including an examination of originals or
copies certified or otherwise identified to our satisfaction of such documents,
corporate records and instruments, as we have deemed necessary or appropriate
for purposes of this opinion.

          In our examination, we have assumed the genuineness of all signatures,
the authenticity of all documents submitted to us as originals, and the
conformity to authentic original documents of all documents submitted to us as
copies.

          We are opining herein as to the effect on the subject transaction only
of the federal laws of the United States, the internal laws of the State of
California and the General Corporation Law of the State of Delaware, and we
express no opinion with respect to the applicability thereto, or the effect
thereon, of the laws of any other jurisdiction or, in the case of


Southwest Water Company
July 6, 2001
Page 2


Delaware any other laws, or as to any matters of municipal law or the laws of
any local agencies within any state.

          Subject to the foregoing and the other matters set forth herein, it is
our opinion that as of the date hereof:

          (1)  When (i) the Indenture has been duly executed and delivered by
     the Company and the Trustee, and (ii) the Securities have been duly issued
     in accordance with the Indenture (including, without limitation, the
     adoption by the Board of Directors of the Company of a resolution duly
     authorizing the issuance and delivery of the Securities), duly
     authenticated by the Trustee and duly executed and delivered on behalf of
     the Company against payment therefor in accordance with the terms and
     provisions of the Indenture and as contemplated by the Registration
     Statement and the Prospectus, and (iii) the Registration Statement and any
     required post-effective amendments thereto have all become effective under
     the Securities Act, and (iv) assuming that the terms of the Securities as
     executed and delivered are as described in the Registration Statement and
     the Prospectus, and (v) assuming that the Securities as executed and
     delivered do not violate any law applicable to the Company or result in a
     default under or breach of any agreement or instrument binding upon the
     Company, and (vi) assuming that the Securities as executed and delivered
     comply with all requirements and restrictions, if any, applicable to the
     Company, whether imposed by any court or governmental or regulatory body
     having jurisdiction over the Company, the Securities will constitute
     legally valid and binding obligations of the Company, enforceable against
     the Company in accordance with their terms.

          (2)  When the Registration Statement and any required post-effective
     amendments thereto have become effective under the Securities Act, and
     assuming that (i) the terms of such shares as executed and delivered are as
     described in the Registration Statement and the Prospectus, (ii) at the
     time of issuance of such shares, the Company has a sufficient number of
     authorized but unissued shares under its Restated Certificate of
     Incorporation, as amended, (iii) such shares as executed and delivered do
     not violate any law applicable to the Company or result in a default under
     or breach of any agreement or instrument binding upon the Company, and (iv)
     such shares as executed and delivered comply with all requirements and
     restrictions, if any, applicable to the Company, whether imposed by any
     court or governmental or regulatory body having jurisdiction over the
     Company, the shares of Common Stock, when issued upon conversion of the
     Securities in accordance with the terms of the Indenture, will be validly
     issued, fully paid and nonassessable.

          The opinions rendered in paragraph 1 relating to the enforceability of
the Securities are subject to the following exceptions, limitations and
qualifications: (i) such opinions are subject to the effect of bankruptcy,
insolvency, reorganization, moratorium or other similar laws relating to or
affecting the rights of creditors; (ii) enforceability of the Securities is
subject to the effect of general principles of equity, including without
limitation concepts of materiality, reasonableness, good faith and fair dealing
and the possible unavailability of specific


Southwest Water Company
July 6, 2001
Page 3


performance or injunctive relief regardless of whether considered in a
proceeding in equity or at law, (iii) certain rights, remedies and waivers
contained in the Indenture may be limited or rendered ineffective by applicable
California law or judicial decisions governing such provisions, but such laws or
judicial decisions do not render the Indenture invalid or unenforceable as a
whole, (iv) we express no opinion concerning the enforceability of the waiver of
rights or defenses contained in Section 7.12 of the Indenture, and (v) we
express no opinion with respect to whether acceleration of Securities may affect
the collectibility of that portion of the stated principal amount thereof which
might be determined to constitute unearned interest thereon.

          To the extent that the obligations of the Company under the Indenture
may be dependent upon such matters, we assume for purposes of this opinion that
the Trustee is duly organized, validly existing and in good standing under the
laws of its jurisdiction of organization; that the Trustee has complied with any
applicable requirements to file returns and pay taxes under the Franchise Tax
Law of the State of California; that the Trustee is duly qualified to engage in
the activities contemplated by the Indenture; that the Indenture, when duly
authorized, executed and delivered by the Trustee will constitute the legally
valid, binding and enforceable obligation of the Trustee enforceable against the
Trustee in accordance with its terms; that the Trustee is in compliance,
generally and with respect to acting as a trustee under the Indenture, with all
applicable laws and regulations; and that the Trustee has the requisite
organizational and legal power and authority to perform its obligations under
the Indenture.

          We consent to your filing this opinion as an exhibit to the
Registration Statement and to the reference to our firm contained under the
heading "Legal Opinions" in the Prospectus included therein.

          This opinion is rendered only to you and is solely for your benefit in
connection with the transactions covered hereby.  This opinion may not be relied
upon by you for any other purpose, or furnished to, quoted to or relied upon by
any other person, firm or corporation for any purpose, without our prior written
consent.

                                   Very truly yours,

                                   /s/ LATHAM & WATKINS