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                                EXHIBIT 10.12A

                              FIRST AMENDMENT OF
                   RTNT RIGHT OF FIRST REFUSAL AGREEMENT AND
                         RTNT CALL PURCHASE AGREEMENT
                                        

     This First Amendment of RTNT Right of First Refusal Agreement and RTNT Call
Purchase Agreement is made and entered into by RTNT, Inc., a Texas Corporation
("RTNT') and Southwest Water Company, Inc., a Delaware Corporation ("SWWC") to
be effective the 22nd day of May 1998.

                                    RECITALS
                                        
     WHEREAS, SWWC and RTNT have previously entered into an RTNT Right of
First Refusal Agreement and RTNT Call Purchase Agreement ("RTNT Call Agreement")
which was executed as of May 23, 1996; and

     WHEREAS this RTNT Call Agreement placed certain restrictions on stock in
Windermere Utility Co., Inc. ("WUC") held by SWWC; and

     WHEREAS this RTNT Call Agreement gave RTNT certain rights to the WUC stock
held by SWWC; and

     WHEREAS the RTNT Call Agreement had certain time periods in which the
rights of RTNT were operative; and

     WHEREAS SWWC and RTNT also entered into a "SWWC Right of First Refusal and
SWWC Call Purchase Agreement" ("SWWC Call Agreement"); and

     WHEREAS the parties hereto being the parties to the SWWC Call Agreement and
the RTNT Call Agreement, for various reasons wish to extend all the time periods
for the exercise of the various rights of RTNT under the RTNT Call Agreement;
and

     NOW, THEREFORE, for and in consideration of the premises and the mutual
covenants and ten dollars ($10.00) and other good and valuable consideration
hereinafter set forth and for other good and valuable consideration including
but not limited to the promises of the parties, the parties hereby agree as
follows:

1.   (a)   The first sentence of Paragraph 1 of the RTNT Call Agreement which is
entitled "Restriction on SWWC Stock" shall be amended to read as follows:

     "SWWC shall not sell, transfer, assign, or otherwise dispose of the SWWC
     WUC stock or any portion thereof to any person or entity for period ending
     on December 31, 1998 plus the period of closing which may be required
     pursuant to this RTNT Call Agreement for RTNT to close the purchase of thc
     SWWC WUC stock upon which it exercises its right to purchase within said
     period ending on December 31. 1998."

(b)  The last sentence of Paragraph 1 of the RTNT Call Agreement which Is
     entitled "Restriction on SWWC Stock" shall be amended to read as follows:

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     "Any pledge of the SWWC WUC stock shall specifically state that it can be
     released within the first twelve (12) months for the Three Million Six
     Hundred Thousand Dollar ($3,600,000.00) call amount and in the thirteenth
     (13th) through the twenty-fourth (24th) month for the Three Million Seven
     Hundred Twenty Thousand Dollar ($3,720,000.00) call amount and within the
     months June 1998 through December 1998 for the Three Million Seven Hundred
     Twenty Thousand Dollar ($3,720,000.00) call amount plus Thirty  Thousand
     Dollars ($30,000.00) for each month that has. elapsed before the exercise
     of the option as set forth herein (i.e. $3,720,000.00 plus $30,000.00 if
     the option is  exercised in June 1998; $3,720,000.00 plus $60,000.00 if the
     option is exercised in July 1998, etc.) in Paragraph 2 below.

2.   The provisions of Paragraph 2 of the RTNT Call Agreement which is entitled
"Call by RTNT," specifically, the first two sentences of Paragraph 2 of the RTNT
Call Agreement shall be amended to read as follows:

     "RTNT shall have, for a period ending on December 31, 1998, the right to
     require SWWC to sell all of the SWWC WUC stock to RTNT.  The purchase price
     for a sale that is initiated (under the closing procedure set out below)
     within the first three hundred sixty-five (365) days after the date hereof
     shall be Three Million Six Hundred Thousand Dollars ($3,600,000.00) and the
     purchase price for a sale that is initiated (under the closing procedures
     set out below) within the period beginning on the three hundred sixty-sixth
     (366th) day and ending on the seven hundred thirtieth (730th) day after the
     date hereof shall be Three Million Seven Hundred Twenty Thousand Dollars
     ($3,720,000.00) and for an option price after the seven hundred thirtieth
     (730th) day and continuing until December 31, 1998, the price shall be as
     follows: Three Million Seven Hundred Twenty Thousand Dollars
     ($3,720,000.00) plus Thirty Thousand Dollars ($30,000.00) per each month
     following May 1998 for each month which passes before the exercise of the
     option by RTNT (i.e. $3,720,000 00 plus $30,000.00 if the option exercise
     Is in June 1998; $3,720,000.00 plus $60,000.00 if  the option exercise is
     in July 1998, etc.)."

3.   The first two sentences of Paragraph 5 of the RTNT Call Agreement which is
entitled "Offer to SWWC" shall be amended to read a follows:

     "In the period following the expiration of the RTNT Call Purchase Provision
     on December 31, 1998, RTNT shall have a Right of First Refusal as set forth
     below. SWVWC shall, after thc expiration of such period terminating on
     December 31, 1998, not sell, transfer, assign, or otherwise dispose of the
     SWWC WUC Stock or any portion thereof to any person and/or entity except as
     provided herein."

4.   The RTNT Call Agreement, the RTNT Call Agreement, the First Amendment to
SWWC Right of First Refusal Agreement and SWWC Call Purchase Agreement, the
First Amendment to RTNT Right of First Refusal Agreement, and the Equity
Agreement and the documents referred to therein, (a) constitute the entire
agreement among the parties and supercede all prior agreements and
understanding, both written and oral, among the parties with respect to the
subject matter hereof, (b) may be executed in several counterparts, each of
which shall constitute one and the same instrument, (c) except as expressly set
forth herein, shall inure to the benefit of, and be binding upon, the
successors, assigns. legal representatives, administrators, and heirs of each
party and are not intended to confer upon any person other than the parties and
their successors assigns, legal representatives, administrators, and heirs any
rights or remedies hereunder, and (d) shall be governed in all respects.
including validity, 

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interpretation, and effect by the laws of the state of Texas. The captions in
this First Amendment to RTNT Right of First Refusal Agreement and RTNT Call
Purchase Agreement are for convenience of reference only and shall not affect
its interpretation in any respect.

5.   Any notice consent or communication required or permitted to be given under
this First Amendment to RTNT Right of First Refusal Agreement and RTNT Call
Purchase Agreement must be in writing and delivered to  a person or by confirmed
facsimile or by registered mail, return receipt requested. postage prepaid
addressee restricted as follows:

          To: RTNT, Inc.,
          P.O. Box 161173
          Austin Texas 78716
          (tel.) 512-327-0869
          (fax) 512-327-0869

          To: Southwest Water Company
          225 North Barranca Avenue Suite 200
          West Covina California 91791-1605
          (tel.) 626-915 1551
          (fax) 626-915-1558


     ANY SUCH NOTICE CONSENT OR OTHER COMMUNICATION SHALL BE DEEMED GIVEN WHEN
DELIVERED IN PERSON OR SENT BY CONFIRMED FACSIMILE OR IF MAILED, FIVE (5) DAYS
AFTER MAILING.

6.   Any provision of this First Amendment to RTNT Right of First Refusal
Agreement and RTNT Call Purchase Agreement which is prohibited or unenforceable
in any jurisdiction as to such jurisdiction be ineffective to the extent of such
prohibition or unenforceability without invalidating the remaining provisions of
this First Amendment to RTNT Right of First Refusal Agreement and RTNT Call
Purchase Agreement and any such prohibition or unenforceability in any
jurisdiction shall not invalidate or render unenforceable such provision in any
other jurisdiction.

7.   This First Amendment to RTNT Right of First Refusal Agreement and RTNT
Call Purchase Agreement shall be subject to the RTNT and SWWC Arbitration
Agreement dated to be effective the 23rd of May 1996.

8.   This First Amendment to RTNT Right of First Refusal Agreement and RTNT
Call Purchase Agreement shall be binding upon and inure to the benefit of SWWC
and RTNT and their respective successors, representatives and assigns.

9.   For purposes hereof, a facsimile copy of this First Amendment of RTNT
Right of First Refusal and RTNT Call Purchase Agreement including the signature
pages hereto shall be deemed to be an original. Notwithstanding the forgoing,
the parties shall deliver original execution copies of this First Amendment of
RTNT Right of First Refusal and RTNT Call Purchase Agreement to one another
immediately after execution.

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Executed as of the 22nd day of May 1998.


                              RTNT, INC., a Texas Corporation

                              By: /s/ Thom W. Farrell        
                                  -------------------        
                                  THOM W. FARRELL, PRESIDENT 
                                                            
                                                            
                              SOUTHWEST WATER COMPANY       
                                                            
                                                            
                              By: /s/ Anton C. Garnier      
                                  --------------------      
                                  ANTON C. GARNIER, PRESIDENT 
     



ATTEST:

/s/ Peter J. Moerbeek
---------------------
PETER MOERBEEK, VICE PRESIDENT
AND SECRETARY

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