<PAGE>

     As Filed with the Securities and Exchange Commission on June 16, 2000
                                                   Registration No. 333-________
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                               __________________

                                    FORM S-8
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                               __________________

                            SOUTHWEST WATER COMPANY
             (Exact name of Registrant as specified in its charter)

         Delaware                                          95-1840947
(State or other jurisdiction of                          (I.R.S. Employer
incorporation or organization)                          Identification No.)

                               __________________

                      225 North Barranca Avenue, Suite 200
                       West Covina, California 91791-1605
                                 (626) 915-1551
          (Address of Principal Executive Offices including Zip Code)

                          Second Amended and Restated
                   Southwest Water Company Stock Option Plan
                            (Full title of the plan)
                               __________________

         PETER J. MOERBEEK                               Copy to:
      Chief Financial Officer                         JAMES W. DANIELS
      SOUTHWEST WATER COMPANY                         LATHAM & WATKINS
  225 North Barranca Avenue, Suite 200         650 Town Center Drive, 20th Floor
  West Covina, California 91791-1605            Costa Mesa, California  92626
          (626) 915-1551                               (714) 540-1235

  (Name and address, including zip code, and telephone number, including area
                          code, of agent for service)


<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------------------------------------

                                                    CALCULATION OF REGISTRATION FEE
------------------------------------------------------------------------------------------------------------------------------------

                                                               Proposed Maximum           Proposed Maximum
    Title of Securities to be           Amount to be          Offering Price Per         Aggregate Offering           Amount of
           Registered                    Registered               Share (2)                  Price (2)             Registration Fee
------------------------------------------------------------------------------------------------------------------------------------

<S>                                     <C>                   <C>                        <C>                        <C>
Common Stock (1)(3)...............        750,000                  $13.29                    $9,967,500                $2,632
------------------------------------------------------------------------------------------------------------------------------------

</TABLE>

(1) The Second Amended and Restated Southwest Water Company Stock Option Plan
    (the "Plan") authorizes the issuance of a maximum of 1,763,905 shares, of
    which 1,013,905 have already been registered pursuant to Form S-8
    Registration Statement Nos. 33-28919, 33-73174 and 333-38935, after giving
    effect to certain stock dividends.  Only the 750,000 newly authorized shares
    under the Plan are being registered hereunder.

(2) Estimated solely for the purpose of calculating the registration fee
    pursuant to Rule 457(h).  The Proposed Maximum Aggregate Offering Price Per
    Share is the average of the high and low price of the common stock, as
    reported on the Nasdaq National Market on June 9, 2000.

(3) Each share of common stock being registered hereunder, if issued prior to
    the termination by the Company of it Stockholders' Rights Agreement dated as
    of April 1998, will include one preferred share purchase right.  Prior to
    the occurrence of certain events, the preferred share purchase rights will
    not be exercisable or evidenced separately from the common stock.
================================================================================
Proposed sale to take place as soon after the effective date of the Registration
           Statement as options granted under the Plan are exercised.

                                 Total Pages 6
                            Exhibit Index on Page 4
<PAGE>

                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

     The information called for in Part I of Form S-8 is not being filed with or
included in this Registration Statement (by incorporation by reference or
otherwise) in accordance with the rules and regulations of the Securities and
Exchange Commission (the "Commission").

                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

     This Registration Statement covers 750,000 additional shares of our common
stock reserved for issuance under the Second Amended and Restated Southwest
Water Company Stock Option Plan (the "Plan").  Effective March 30, 2000, our
board of directors adopted, and on May 23, 2000, our stockholders approved, an
amendment to the Plan which increased the number of shares reserved for issuance
thereunder by 750,000 shares.  On May 22, 1997, December 21, 1993 and October
29, 1997 we filed with the Commission Form S-8 Registration Statement Nos. 33-
28919, 33-73174 and 333-38935, respectively (collectively, the "Prior
Registration Statements"), covering an aggregate of 515,000 shares issuable
under the Plan, which has increased to an aggregate of 1,013,906 shares after
giving effect to certain stock dividends.  The contents of the Prior
Registration Statements are incorporated by reference herein to the extent not
modified or superseded thereby or by any subsequently filed document which is
incorporated by reference herein or therein.

Item 5. Named Experts
        -------------

     Our consolidated financial statements and related schedules, which are
incorporated in this Registration Statement by reference to our Annual Report on
Form 10-K for the year ended December 31, 1999, have been so included in
reliance on the reports of KPMG LLP, independent auditors, incorporated by
reference, upon the authority of said firm as experts in auditing and
accounting.

Item 8.  Exhibits
         --------

See Index to Exhibits on page 4.


                                       2
<PAGE>

SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, as amended, we
certify that we have reasonable grounds to believe that we meet all of the
requirements for filing on Form S-8 and have duly caused this registration
statement to be signed on our behalf by the undersigned, thereunto duly
authorized, in the City of West Covina, State of California, on this 15th day
of June, 2000.

                                    Southwest Water Company,
                                    a Delaware corporation


                                    By: /s/ Anton C. Garnier
                                       --------------------------------------
                                            Anton C. Garnier
                                        President and Chief Executive Officer


                               POWER OF ATTORNEY

     Each person whose signature appears below hereby authorizes and appoints
Peter J. Moerbeek, as attorney-in-fact and agent, with full powers of
substitution to sign on his or her behalf, individually and in the capacities
stated below, and to file any and all amendments, including post-effective
amendments, to this registration statement and other documents in connection
therewith, with the Commission, granting to said attorney-in-fact and agent full
power and authority to perform any other act on behalf of the undersigned
required to be done in the premises.

     Pursuant to the requirements of the Securities Act, this registration
statement has been signed by the following persons in the capacities indicated
on June 15, 2000.

<TABLE>
<CAPTION>
Signature                              Title
---------                              -----
<S>                                    <C>

/s/ Anton C. Garnier
-----------------------------
Anton C. Garnier                       President and Chief Executive Officer,
                                       Director
                                       (Chief Executive Officer)


/s/ Peter J. Moerbeek
-----------------------------
Peter J. Moerbeek                      Chief Financial Officer
                                       (Principal Financial and Accounting
                                       Officer)

/s/ H. Frederick Christie
-----------------------------
H. Frederick Christie                  Director

/s/ Monroe Harris
-----------------------------
Monroe Harris                          Director

/s/ Donovan D. Huennekens
-----------------------------
Donovan D. Huennekens                  Director

/s/ Richard Kelton
-----------------------------
Richard Kelton                         Director

/s/ Maureen A. Kindel
-----------------------------
Maureen A. Kindel                      Director

/s/ Richard G. Newman
-----------------------------
Richard G. Newman                      Director
</TABLE>


                                       3
<PAGE>

                               INDEX TO EXHIBITS


<TABLE>
<CAPTION>
  EXHIBIT              DESCRIPTION
  -------              -----------
<S>                    <C>
     4                 Stockholders' Rights Agreement, dated as of April 6, 1998
                       (incorporated by reference to our Form 8-K filed with the
                       SEC on April 23, 1998).

    5.1                Opinion of and Consent of Latham & Watkins.

   23.1                Consent of Latham & Watkins (included in Exhibit 5.1).

   23.2                Consent of Independent Auditors.

    24                 Power of Attorney (included on the signature page to this
                       Registration Statement).
</TABLE>


                                       4
[{"type": "S-8", "sequence": "1", "filename": "0001.txt", "description": "FORM S-8", "secsgml_size_bytes": 10549}]
{"company-data": {"conformed-name": "SOUTHWEST WATER CO", "cik": "0000092472", "assigned-sic": "4941", "irs-number": "951840947", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-39506", "film-number": "656555"}, "business-address": {"street1": "225 N BARRANCA AVE STE 200", "city": "WEST COVINA", "state": "CA", "zip": "91791-1605", "phone": "8189151551"}, "mail-address": {"street1": "225 N BARRANCA AVENUE", "street2": "SUITE 200", "city": "WEST COVINA", "state": "CA", "zip": "91791-1605"}, "former-company": {"former-conformed-name": "SUBURBAN WATER SYSTEMS", "date-changed": "19751202"}}
As Filed with the Securities and Exchange Commission on June 16, 2000
                                                   Registration No. 333-________
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                               __________________

                                    FORM S-8
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                               __________________

                            SOUTHWEST WATER COMPANY
             (Exact name of Registrant as specified in its charter)

         Delaware                                          95-1840947
(State or other jurisdiction of                          (I.R.S. Employer
incorporation or organization)                          Identification No.)

                               __________________

                      225 North Barranca Avenue, Suite 200
                       West Covina, California 91791-1605
                                 (626) 915-1551
          (Address of Principal Executive Offices including Zip Code)

                          Second Amended and Restated
                   Southwest Water Company Stock Option Plan
                            (Full title of the plan)
                               __________________

         PETER J. MOERBEEK                               Copy to:
      Chief Financial Officer                         JAMES W. DANIELS
      SOUTHWEST WATER COMPANY                         LATHAM & WATKINS
  225 North Barranca Avenue, Suite 200         650 Town Center Drive, 20th Floor
  West Covina, California 91791-1605            Costa Mesa, California  92626
          (626) 915-1551                               (714) 540-1235

  (Name and address, including zip code, and telephone number, including area
                          code, of agent for service)
------------------------------------------------------------------------------------------------------------------------------------

                                                    CALCULATION OF REGISTRATION FEE
------------------------------------------------------------------------------------------------------------------------------------

                                                               Proposed Maximum           Proposed Maximum
    Title of Securities to be           Amount to be          Offering Price Per         Aggregate Offering           Amount of
           Registered                    Registered               Share (2)                  Price (2)             Registration Fee
------------------------------------------------------------------------------------------------------------------------------------
Common Stock (1)(3)...............        750,000                  $13.29                    $9,967,500                $2,632
------------------------------------------------------------------------------------------------------------------------------------
(1) The Second Amended and Restated Southwest Water Company Stock Option Plan
    (the "Plan") authorizes the issuance of a maximum of 1,763,905 shares, of
    which 1,013,905 have already been registered pursuant to Form S-8
    Registration Statement Nos. 33-28919, 33-73174 and 333-38935, after giving
    effect to certain stock dividends.  Only the 750,000 newly authorized shares
    under the Plan are being registered hereunder.

(2) Estimated solely for the purpose of calculating the registration fee
    pursuant to Rule 457(h).  The Proposed Maximum Aggregate Offering Price Per
    Share is the average of the high and low price of the common stock, as
    reported on the Nasdaq National Market on June 9, 2000.

(3) Each share of common stock being registered hereunder, if issued prior to
    the termination by the Company of it Stockholders' Rights Agreement dated as
    of April 1998, will include one preferred share purchase right.  Prior to
    the occurrence of certain events, the preferred share purchase rights will
    not be exercisable or evidenced separately from the common stock.
================================================================================
Proposed sale to take place as soon after the effective date of the Registration
           Statement as options granted under the Plan are exercised.

                                 Total Pages 6
                            Exhibit Index on Page 4
PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

     The information called for in Part I of Form S-8 is not being filed with or
included in this Registration Statement (by incorporation by reference or
otherwise) in accordance with the rules and regulations of the Securities and
Exchange Commission (the "Commission").

                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

     This Registration Statement covers 750,000 additional shares of our common
stock reserved for issuance under the Second Amended and Restated Southwest
Water Company Stock Option Plan (the "Plan").  Effective March 30, 2000, our
board of directors adopted, and on May 23, 2000, our stockholders approved, an
amendment to the Plan which increased the number of shares reserved for issuance
thereunder by 750,000 shares.  On May 22, 1997, December 21, 1993 and October
29, 1997 we filed with the Commission Form S-8 Registration Statement Nos. 33-
28919, 33-73174 and 333-38935, respectively (collectively, the "Prior
Registration Statements"), covering an aggregate of 515,000 shares issuable
under the Plan, which has increased to an aggregate of 1,013,906 shares after
giving effect to certain stock dividends.  The contents of the Prior
Registration Statements are incorporated by reference herein to the extent not
modified or superseded thereby or by any subsequently filed document which is
incorporated by reference herein or therein.

Item 5. Named Experts
        -------------

     Our consolidated financial statements and related schedules, which are
incorporated in this Registration Statement by reference to our Annual Report on
Form 10-K for the year ended December 31, 1999, have been so included in
reliance on the reports of KPMG LLP, independent auditors, incorporated by
reference, upon the authority of said firm as experts in auditing and
accounting.

Item 8.  Exhibits
         --------

See Index to Exhibits on page 4.

                                       2
SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, as amended, we
certify that we have reasonable grounds to believe that we meet all of the
requirements for filing on Form S-8 and have duly caused this registration
statement to be signed on our behalf by the undersigned, thereunto duly
authorized, in the City of West Covina, State of California, on this 15th day
of June, 2000.

                                    Southwest Water Company,
                                    a Delaware corporation

                                    By: /s/ Anton C. Garnier
                                       --------------------------------------
                                            Anton C. Garnier
                                        President and Chief Executive Officer

                               POWER OF ATTORNEY

     Each person whose signature appears below hereby authorizes and appoints
Peter J. Moerbeek, as attorney-in-fact and agent, with full powers of
substitution to sign on his or her behalf, individually and in the capacities
stated below, and to file any and all amendments, including post-effective
amendments, to this registration statement and other documents in connection
therewith, with the Commission, granting to said attorney-in-fact and agent full
power and authority to perform any other act on behalf of the undersigned
required to be done in the premises.

     Pursuant to the requirements of the Securities Act, this registration
statement has been signed by the following persons in the capacities indicated
on June 15, 2000.
Signature                              Title
---------                              -----
/s/ Anton C. Garnier
-----------------------------
Anton C. Garnier                       President and Chief Executive Officer,
                                       Director
                                       (Chief Executive Officer)

/s/ Peter J. Moerbeek
-----------------------------
Peter J. Moerbeek                      Chief Financial Officer
                                       (Principal Financial and Accounting
                                       Officer)

/s/ H. Frederick Christie
-----------------------------
H. Frederick Christie                  Director

/s/ Monroe Harris
-----------------------------
Monroe Harris                          Director

/s/ Donovan D. Huennekens
-----------------------------
Donovan D. Huennekens                  Director

/s/ Richard Kelton
-----------------------------
Richard Kelton                         Director

/s/ Maureen A. Kindel
-----------------------------
Maureen A. Kindel                      Director

/s/ Richard G. Newman
-----------------------------
Richard G. Newman                      Director
3
INDEX TO EXHIBITS
EXHIBIT              DESCRIPTION
  -------              -----------
4                 Stockholders' Rights Agreement, dated as of April 6, 1998
                       (incorporated by reference to our Form 8-K filed with the
                       SEC on April 23, 1998).

    5.1                Opinion of and Consent of Latham & Watkins.

   23.1                Consent of Latham & Watkins (included in Exhibit 5.1).

   23.2                Consent of Independent Auditors.

    24                 Power of Attorney (included on the signature page to this
                       Registration Statement).
4