<PAGE>
                                                                   Exhibit 10.30

                   SUBLEASE EXTENSION AND AMENDMENT AGREEMENT
                   ------------------------------------------

AGREEMENT made this 17th day of June, 1999, between GENERAL MOTORS CORPORATION,
a Delaware corporation, with its principal address at 3044 West Grand
Boulevard, Detroit, Michigan 48202, hereinafter referred to as Sublessor, and
U.S. FILTER DISTRIBUTION GROUP, INC., a Georgia corporation, with its principal
address at 200 Highway 6 West, American Plaza, Suite 620, Waco, Texas 76712,
hereinafter referred to as Sublessee,

                              W I T N E S S E T H:

That the Sublease Agreement dated April 16, 1990, as extended and amended,
between the Sublessor and Water Products Company, whose interest is now vested
in the Sublessee herein covering approximately 27,000 rentable square feet at
1910 38th Street, Denver, Colorado, for a term commencing April 16, 1990, and
as extended expiring December 31, 1999, is hereby extended and amended as
follows:

(1)  Effective January 1, 2000, the term of said Sublease is extended for a
     further period so as to expire December 31, 2004.

(2)  Effective January 1, 2000, the rental shall be increased from SIXTY
     THOUSAND SEVEN HUNDRED FIFTY AND 00/100 DOLLARS ($60,750.00) per year to
     SIXTY-SEVEN THOUSAND FIVE HUNDRED AND 00/100 DOLLARS ($67,500.00) per year,
     payable in advance in equal monthly installments of $5,625.00.

Except as heretofore and hereby amended and extended, said Sublease Agreement
dated April 16, 1990, is in all respects ratified and confirmed.

IN WITNESS WHEREOF, the Sublessor has signed and sealed this instrument this
12th
<PAGE>
day of July, 1999, and the Sublessee has signed and sealed this instrument this
22th day of June, 1999.


In the presence of:                     GENERAL MOTORS CORPORATION

/s/ Illegible                         BY  /s/ Conrad P. Schwactz
_________________________                 _______________________________
                                                     Director
                                              Worldwide Real Estate


/s/ Gregg L. Moore                      ATTEST  /s/ Bernice C. Heady
_________________________                     ____________________________
                                                    Bernice C. Heady
                                                   Assistant Secretary



In the presence of:                     U.S. FILTER DISTRIBUTION GROUP, INC.

/s/ Susan Chapman                       BY   /s/ Illegible
_________________________                 _________________________________
                                                  Vice - President

/s/ ILLEGIBLE                           ATTEST   /s/ ILLEGIBLE
_________________________                     ______________________________
                                                  Asst. Secretary



                                      -2-
<PAGE>
                        ESTOPPEL CERTIFICATE AND CONSENT

     General Motors Company, a Delaware corporation ("SUBLESSOR"), being the
sublessor of the premises located at 1910 38th Street, Denver, Colorado (the
"PREMISES") pursuant to a Sublease dated April 16, 1990, as amended by the
Letter dated April 10, 1991, and as further amended by the Sublease Extension
and Amendment Agreement dated August 9, 1993 (collectively, the "SUBLEASE"), by
and between Sublessor and Water Products Company, whose interest is now vested
in WaterPro Supplies Corporation, a Massachusetts corporation ("SUBLESSEE"), for
good and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, and intending to be legally bound hereby, certifies and
acknowledges to United States Filter Corporation, a Delaware corporation ("U.S.
FILTER"), in connection with the acquisition of Sublessee by U.S. Filter as
follows:

          1.   The Sublease constitutes the entire agreement between Sublessor
and Sublessee with respect to the Leasehold Premises and to the best of
Sublessor's knowledge has not been assigned, supplemented, amended, modified in
any way, canceled or terminated and remains in full force and effect. The
expiration date of the extended term of the Sublease is December 31, 1999. The
current monthly rent under the Sublease is $4,612.50, which will increase on
January 1, 1997, to $5,062.50 per month for the remainder of the extended term.

          2.   All terms, covenants, provisions and conditions to be performed
or observed by Sublessee, to date, under the Sublease have been performed,
observed and complied with, no default or event of default by Sublessee exists
under the Sublease, and there does not now exist any condition which, if
remaining uncured, would result in a default by Sublessee under the Sublease. No
rent, sums, assessments, dues or charges required to be paid by Sublessee under
the Sublease are past due.

          3.   Sublessor has not received any notice of default from Sublessee.

          4.   In connection with the acquisition of Sublessee by U.S. Filter,
Sublessor hereby consents to: (i) the acquisition of all of Sublessee's issued
and outstanding stock by U.S. Filter Distribution, Inc., a subsidiary of U.S.
Filter; and (ii) following such acquisition, the merger of Sublessee with and
into U.S. Filter Distribution Systems, Inc.

          5.   The persons executing this instrument on behalf of Sublessor have
personal knowledge of the matters stated herein and have all necessary power and
authority to execute and deliver this instrument on behalf of Sublessor and, in
so doing, to bind Sublessor in accordance with the terms and provisions hereof.

     IN WITNESS WHEREOF, the undersigned has executed this instrument this 31st
day of October, 1996.

WITNESS:                           GENERAL MOTORS COMPANY

/s/ M.J. Ansley                    By:    /s/ M.P. Cullen
------------------------                  ----------------------------
M.J. Ansley                               M.P. Cullen, Director
                                   Title: Worldwide Real Estate
                                          ----------------------------
<PAGE>
                   SUBLEASE EXTENSION AND AMENDMENT AGREEMENT

AGREEMENT made this 9th day of August, 1993, between GENERAL MOTORS
CORPORATION, a Delaware corporation, with its principal address at 3044 West
Grand Boulevard, Detroit, Michigan 48202, hereinafter referred to as Sublessor,
and WATERPRO SUPPLIES CORPORATION, a Massachusetts corporation, with its
principal address at 7887 Fuller Road, Eden Prairie, Minnesota 55344,
hereinafter referred to as Sublessee,

                              W I T N E S S E T H:

That the Sublease dated April 16, 1990, as amended by a letter agreement dated
April 10, 1991 (hereinafter referred to as "Sublease"), between Water Products
Company, whose interest is now vested in the Sublessee herein, and Sublessor
covering premises known as 1910 38th Street, Denver, Colorado, for a term
commencing April 16, 1990, and expiring December 31, 1994, is hereby extended
and amended as follows:

(1)  The term of said Sublease is hereby extended for a further period so as to
     expire December 31, 1999.

(2)  Effective January 1, 1995, through December 31, 1996, the rental shall be
     FIFTY-FIVE THOUSAND THREE HUNDRED FIFTY AND 00/100 DOLLARS ($55,350.00) per
     year, payable in advance in equal monthly installments of $4,612.50.

(3)  Effective January 1, 1997, through December 31, 1999, the rental shall be
     SIXTY THOUSAND SEVEN HUNDRED FIFTY AND 00/100 DOLLARS ($60,750.00) per
     year, payable in advance in equal monthly installments of $5,062.50.

(4)  Sublessor represents and warrants that the underlying Lease for the
     premises between Sublessor and Eline Properties of Delaware, Inc., remains
     in full force and effect for a term currently extending at least through
     December 31, 1999, that there has occurred no
<PAGE>
     defaults thereunder, and that Sublessor has obtained all required consents
     under the underlying Lease necessary for Sublessor to enter into and
     perform the Sublease as amended and extended hereby.

Except as hereby amended and extended, said Sublease is in all respects
ratified and confirmed.

IN WITNESS WHEREOF, the Sublessor has signed and sealed this instrument this
21st day of September, 1993, and the Sublessee has signed and sealed this
instrument this 9th day of September, 1993.


In the presence of:                    GENERAL MOTORS CORPORATION

                                       By W.J. O'Keefe
-------------------------------------     --------------------------------------

/s/ Bernice C. Heady                   ATTEST /s/ ILLEGIBLE
-------------------------------------        -----------------------------------

                                                             Assistant Secretary


In the presence of:                    WATERPRO SUPPLIES CORPORATION

ILLEGIBLE                              By /s/ ILLEGIBLE
-------------------------------------    ---------------------------------------
                                                                       President

/s/ ILLEGIBLE                          ATTEST /s/ ILLEGIBLE
-------------------------------------         ----------------------------------

                                                                           Clerk








                                      -2-
<PAGE>
                                   [GM LOGO]

                           General Motors Corporation


                                 April 10, 1991


Water Products Company
15801 W. 78th Street
Eden Prairie, MN 55344


     Re:  Sublease dated as of April 16, 1990
          Sublessee: Water Products Company
          Sublessor: General Motors Corporation
          Premises: 1910 - 38th Street
                    Denver, Colorado


Dear Sirs:

     The purpose of this letter is to serve as a clarification of the above
described Sublease regarding the parties' obligation for real estate taxes. From
the date of Sublessee's possession and throughout the term of the Sublease, the
responsibility for payment of the real estate taxes for which the premises are
subject shall be the sole responsibility of Sublessee. Sublessor shall forward
copies of the real estate tax bills and Sublessee shall pay same directly to the
taxing authority prior to any interest or penalties accruing. Sublessee shall
provide Sublessor with proof of timely payment of the taxes. In the event
Sublessee fails to pay said taxes, Sublessor may, but shall not have the
obligation to, pay said taxes and charge them to Sublessee as rent. Failure of
Sublessee to pay said taxes in a timely manner shall constitute a material
default of the Sublease and Sublessor shall be provided with the remedies upon
default contained in the Sublease. The taxes shall be allocated on a prorata
basis at the beginning and end of the Sublease term.

     The terms contained in this letter agreement shall control over
inconsistencies or conflicts with the Sublease.
<PAGE>
Water Products Company
April 10, 1991
Page 2


     Please indicate your acceptance and agreement to the above terms by your
signature below and returning a fully executed copy of this letter to the
undersigned.


                                        GENERAL MOTORS CORPORATION

                                        By: /s/ W.J. O'Keefe
                                        --------------------------------------
                                        W.J. O'KEEFE
                                        Executive Director, Corporate Services

Accepted and agreed to:

WATER PRODUCTS COMPANY

By: /s/ Mark C. Miller
    -----------------------
Date 4-26-91                                 By: /s/ illegible
     ----------------------                      -----------------------------

<PAGE>
                                    SUBLEASE

     THIS SUBLEASE, dated as of April 16, 1990, between GENERAL MOTORS
CORPORATION, whose principal office is located at 3044 W. Grand Boulevard,
Detroit, Michigan 48202, hereinafter called the Sublessor, and WATER PRODUCTS
COMPANY, whose address is 15801 W. 78th Street, Eden Prairie, Minnesota 55344,
hereinafter called the Sublessee.

                                   WITNESSETH

       THE PARTIES HERETO COVENANT AND AGREE WITH EACH OTHER AS FOLLOWS:

1.   PREMISES.  Sublessor hereby lets to Sublessee and Sublessee hires from
Sublessor the following described premises:

          1910 38th Street, Denver, Colorado, and more
          particularly described in Exhibit "A" attached
          hereto and made a part hereof ("Premises").

2.   USE AND TERM.  The Premises is to be used for an office and warehouse or
any type of business, or any other lawful purpose not inconsistent with the
character of the premises, for a term commencing April 16, 1990 and expiring
December 31, 1994; provided, however, that the Premises may not be used to
treat, store, or dispose of hazardous substances, hazardous wastes, or toxic
substances as those terms are defined under applicable federal and state
environmental laws.

3.   RENT.  No base rent shall be charged to Sublessee from April 16, 1990
through November 16, 1990. The rent of Three Thousand Seven Hundred Twelve and
50/100 ($3,712.50) Dollars per month for the period of November 17, 1990,
through March 31, 1993 and of Four Thousand One Hundred Sixty-Two and 50/100
($4,162.50) Dollars per month for the period commencing April 1, 1993 through
December 31, 1994 shall be paid by Sublessee to Sublessor. Rent during each said
month as charged above shall be prorated for any partial month and shall be
payable in advance on the first business day of said month or partial month.

4.   SUBLEASE.  This is a Sublease and the Sublessor's interest in the premises
is as Lessee under an underlying Lease originally made by and between ELINE
PROPERTIES OF DELAWARE, INC., as Lessor, and GENERAL MOTORS CORPORATION, as
Lessee, dated April 7, 1959. The underlying Lease is in full force and effect
and there have been no defaults thereunder. Sublessor has obtained all required
consents under the underlying Lease necessary for Sublessor to enter into and
perform this Sublease. Sublessor will seek prior approval of Sublessee for any
changes to said underlying Lease that affect Sublessee's rights hereunder.

5.   MAINTENANCE AND REPAIRS.  The Sublessee shall maintain and repair as
necessary, the interior and the exterior of the building including the roof
(except if any such roof repairs or replacement exceeds One Thousand ($1,000.00)
Dollars for a single roof repair or replacement job, the Sublessee shall be
reimbursed by Sublessor for the amount of such roof repair or replacement in
excess of said One Thousand ($1,000.00) Dollars), exterior walls, drains, eaves
troughs, downspouts, gutters, exterior painting and ongoing incidental repair to
the building.


[7901]                                                                    Page 1
<PAGE>
The Sublessee shall keep and not misuse the premises so that they may be
returned to the Sublessor in as good an order and condition as when delivered to
Sublessee, excepting ordinary wear and tear, damage by fire, vandalism, the
elements and casualty, and damage due to any cause or happening not occasioned
by the negligence of the Sublessee. The Sublessee shall maintain, repair and
replace as necessary the plumbing, heating, ventilating and air conditioning
equipment, lighting and other electrical and mechanical equipment, sprinkler
system, elevators, glass, damage by vandals, and make all other repairs and
replacements including termite damage. The Sublessee shall also maintain, repair
and replace as necessary, the improvements and the lands which are a part of and
used in connection with the premises, including but not limited to ditches,
drains, sewers, utility lines, driveways, sidewalks, parking areas, lighting,
landscaping and fencing subject to the terms and provisions of Paragraph
Twenty-Four. If Sublessee shall fail to perform the repairs and maintenance set
forth above, Sublessor may elect to have such repair or maintenance performed at
its expense and seek reimbursement from the Sublessee. In such event Sublessee
shall also be liable to Sublessor for interest on such reimbursement amounts at
the highest interest rate allowable by law for the period commencing with
Sublessor's payment of such cost up to the date of its receipt of reimbursement
from Sublessee. In addition, if Sublessor shall commence a legal action against
Sublessee to obtain such reimbursement, Sublessee shall be liable to Sublessor
for all incidental costs incurred by Sublessor in conducting such legal action
including but not limited to court costs and reasonable legal fees incurred.

Anything to the contrary notwithstanding, Sublessor warrants the structural
integrity of the building and any structural fault which requires repair or
replacement (excepting the roof for which repair and replacement is as provided
for above) shall be the responsibility of and shall be paid by the Sublessor.

6.   EASEMENTS.  The enjoyment and use of all entrances, exits, approaches and
means of entrance and approach, and of light and air now existing in favor of
the demised Premises shall not be interfered with or interrupted by any act or
asset of the Sublessor during the term of this Sublease.

7.   ASSIGNMENT.  The Sublessee will not assign this Sublease without the
written consent of the Sublessor.

8.   NEGATIVE COVENANTS.  The Sublessee will not consent to any use of the
demised premises which shall be contrary to any valid ordinance or bylaw of any
municipality governing the Premises.

9.   CONDITION OF PREMISES.  Sublessee acknowledges that it has inspected the
Premises and agrees to enter into this Sublease Agreement and take possession of
the Premises in its "as is" condition, except as otherwise provided in Section 5
hereof. Sublessor makes no warranties or representations as to the condition of
the Premises, except as otherwise provided in Section 5 hereof.


[7901]                                                                    Page 2
<PAGE>
10.  VIEWING PREMISES. The Sublessor may during the term at reasonable times
enter to view the Premises and may at any time within six (6) months before the
expiration of the said term, show the said Premises and building or buildings
to others, and affix to any suitable part of the said Premises a notice for
letting or selling the Premises, or building or buildings and keep the same
affixed without hindrance or molestation.

11.  DESTRUCTION OF PREMISES. If the Premises shall be damaged by fire, the
elements, casualty, war, insurrection, riot, public disorder, act, authorized
or unauthorized, on the part of any governmental authority of any cause or
happening as to be substantially destroyed, then this Sublease shall cease and
come to an end, and any unearned rent paid in advance by the Sublessee shall be
refunded to it.

In the case of only partial damage or destruction of the Premises or of other
portions of the building or buildings containing the Premises, then said
Premises or other portions of said building or buildings may be restored by the
Sublessor to their previous condition and a just proportion of the rent herein
reserved, according to the extent to which they have been rendered
untenantable, shall abate until the said Premises shall have been so restored
and put in proper condition for use and occupancy, and a just proportion of any
rent paid in advance by the Sublessee shall be refunded to it. Nonetheless, in
the event of such partial damage or destruction of the Premises, Sublessor may
elect to terminate this Lease upon five (5) days notice to Sublessee.

The Sublessor shall maintain fire and supplemental perils insurance coverage in
an amount sufficient to comply with the aforementioned provisions of this
Agreement.

If any authority having jurisdiction shall decide that the said building or
buildings should be demolished and removed, then forthwith upon such decision
being made and upon the Sublessee vacating the Premises, this Sublease shall
cease and come to an end and any unearned rent paid in advance by the Sublessee
shall be refunded to it.

12.  UNLAWFUL OCCUPATION. The Sublessor represents that the Premises may be used
for the purposes for which they are hereby leased and in the event of the
enactment or existence of any law, ordinance, rule, ruling, regulation, covenant
or restriction prohibiting or limiting the use of said Premises for any one or
more of the purposes for which they are hereby leased, then in that event at the
option of the Sublessee, this Sublease shall terminate and all liability
hereunder shall cease from and after the date such prohibition becomes
effective, and any unearned rent paid in advance by the Sublessee shall be
refunded to it.

13. RIGHTS UPON DEFAULT. If the Sublessee shall neglect or fail to perform or
observe any of the covenants contained herein on its part to be observed and
performed for thirty (30) days after written notice by the Sublessor, or if the
Sublessee shall be adjudicated bankrupt or insolvent according to law, or shall
make an assignment for the benefit of creditors, then and in any of said cases
the Sublessor may lawfully enter into and upon the said Premises or any part
thereof in the name of the whole, and repossess the same as of the former estate
of the

[7901]                                                                    Page 3


<PAGE>
Sublessor and expel the Sublessee and those claiming under and through it and
remove its effects (forcibly if necessary), without being deemed guilty of any
manner of trespass, and without prejudice to any remedies which might otherwise
be used for arrears of rent or preceding breach of covenant and upon entry as
aforesaid this Sublease shall terminate and the Sublessee covenants that in case
of such termination it will indemnify the Sublessor against all unavoidable loss
of rent which the Sublessor may incur by reason of such termination during the
residue of the term above specified.

14. TERMINATION.  Notwithstanding any provision of law or any judicial decision
to the contrary, (a) no notice shall be required to terminate the term of this
Sublease on December 31, 1994 and the term hereof shall expire on such date
without notice being required from either party; (b) in the event that the
Sublessee, any assignee, or sub-sublessee remains beyond the expiration date of
the term herein, it is the intention of the parties and it is hereby agreed that
a tenancy from month to month shall arise upon all the same terms and conditions
contained herein.

15. QUIET POSSESSION.  Sublessor hereby covenants that Sublessee on paying the
rent and performing all and singular the covenants and conditions of this
Sublease on its part to be performed, shall and may peaceably and quietly have,
hold and enjoy the demised premises for the term aforesaid, and for the term of
any renewal or renewals hereof, free from molestation, eviction or destruction
by the Sublessor, or by any other person or persons lawfully claiming the same.
Sublessor herein represents that it has good right to make this Sublease for the
full term hereby granted, including any period for which the Sublessee may have
the  right to effect a renewal hereof. Sublessor further agrees that in the
event the Sublease is assigned during the term of this Sublease or any extension
thereof, an executed copy of the Assignment of this Sublease shall be furnished
to Sublessee, it being understood that the consideration for such conveyance may
be deleted from such instruments.

16. SERVICES TO BE OBTAINED BY SUBLESSEE. The Sublessee shall be responsible for
obtaining and paying for utility services for the Premises, including electric
current for all purposes required by the Sublessee, janitor service, snow
removal, water, sewer, elevator service, gas and fuel, as Sublessee may require,
and fluorescent tubes or electric bulbs for lamps for lighting the demised
Premises and the Sublessee shall renew all such fluorescent tubes or bulbs when
necessary.

17. ALTERATIONS BY SUBLESSEE.  With the prior written consent of Sublessor, the
Sublessee shall have the right at any time during the term or any extension
thereof, at its own expense to make alterations, changes, improvements, and
remodeling to the demised Premises, inside or outside, provided the same shall
be in conformity with the building laws governing such construction. In case of
said alterations, changes, improvements and remodeling, the Sublessee shall not
be required upon the termination of the Sublease or any extension thereof to
restore the Premises to their original condition.

18. FIXTURES AND EQUIPMENT.  All machinery, movable partitions, fixtures or
equipment installed in the demised Premises at the Sublessee's expense

                                                                          Page 4
<PAGE>
shall remain the property of the Sublessee and may be removed by the Sublessee.
The Sublessee shall, however, repair any damage caused directly and exclusively
by said removal.

19. SIGNS.  The Sublessee after written approval by Sublessor, which approval
shall not be unreasonably withheld, shall have the right to install or place a
sign on or about the demised Premises and upon removal of said sign at the
termination of this Sublease shall repair any damage caused by such
installation and removal.

20. CONDEMNATION.  In the event the Premises or any part thereof are taken or
condemned by a temporary or permanent public or quasi-public use so as to
interfere with Sublessee's use, Sublessee may at its option terminate this
Sublease and, in such event, any unearned rent paid in advance shall be returned
to Sublessee, but nothing herein contained shall prevent Sublessee from
recovering any damages sustained by Sublessee due to such taking.

21. MORTGAGE SUBORDINATION.  This Sublease shall be subject and subordinate to
the lien of any mortgages hereafter placed on the Premises and Sublessee agrees
to execute and deliver upon demand, in confirmation of such subordination, such
further instruments as shall be required by any mortgages or proposed mortgages.
Provided, that if and when such mortgage or mortgages are placed, the mortgagee
shall agree for itself and for every subsequent holder or owner of the mortgage
and for any receiver or purchaser of the Premises in the event of foreclosure,
Sublessee's quiet possession of the Premises will not be disturbed on account of
said mortgage or by reason of anything done thereunder so long as Sublessee pays
the rent and performs all other covenants required of it hereunder.

22. NOTICES.  All notices to be given hereunder shall be in writing and given by
personal delivery to only the executive officers of the Sublessor or to one of
the executive officers of the Sublessee or shall be sent by telegram or by
registered mail addressed to the party intended to be notified at the post
office address of such party last known to the party giving such notice and
notice given as aforesaid shall be a sufficient service thereof, and shall be
deemed given as of the date when  deposited in any post office, or in any post
office box regularly maintained by the Federal Government or, in the case of a
telegram, when given to an employe of the telegraph company for transmission.
Provided, however, that it is mutually agreed that the Sublessor appoints the
President, the Executive Vice-President, and the Vice-President in charge of
real estate, General Motors Corporation, and the Executive in charge of real
estate, the Manager and the Director, Real Estate Department of Argonaut Realty
Division, General Motors Corporation, Argonaut Building, 485 W. Milwaukee
Avenue, Detroit, Michigan 48202, as its agents and that any one of them may give
all notices and receive all notices to be given hereunder and may receive the
rent.

23. INSURANCE.  Sublessor shall maintain and keep in full force and effect
during the term of this Sublease property damage and casualty insurance in the
amount equal to at least the full replacement value of the improvements on the
Premises. Sublessee shall keep and maintain

                                                                          Page 5
<PAGE>
during the term of this Sublease public liability insurance coverage in the
amount of One Million ($1,000,000.00) Dollars for personal injury or death
resulting from any one occurrence and such policy shall include the Sublessor
as an additional insured.

24. YARD MAINTENANCE AND REPAIR.  Sublessor and Sublessee acknowledge that the
paved yard on the west side of the existing building on the Premises is in good
condition as of the date of execution of this Sublease and that Sublessee is
solely responsible for the maintenance of such yard during the normal
day-to-day usage in Sublessee's business. Should significant disrepair in such
yard occur during the term of this Lease due to sources other than the normal
day-to-day usage by Sublessee, then Sublessor shall bear the cost to repair
said yard.

The covenants and agreements contained in the foregoing Sublease are binding
upon the parties hereto and their respective heirs, executors, administrators,
successors, legal representatives and assigns.

IN WITNESS WHEREOF, Sublessor has executed this Agreement on the 30th day of
May, 1990, and Sublessee has executed this Agreement on the ____ day of
_________, 1990.


WITNESSES:                             SUBLESSOR:


                                       GENERAL MOTORS CORPORATION


                                   BY:  /S/ W.J. O'Keefe
---------------------------------      --------------------------------------
                                            W.J. O'Keefe
/s/ Bernice C. Heady                   Executive Director, Corporate Services
---------------------------------      --------------------------------------



                                       SUBLESSEE:


                                       WATER PRODUCTS COMPANY


                                   BY:  /S/ Mark C. Miller
---------------------------------      --------------------------------------
                                            VP Admin
---------------------------------      --------------------------------------




                                                                         Page 6

<PAGE>
                                  EXHIBIT A

All the following described or parcel of land, situate, lying and being in the
City and County of Denver, and State of Colorado, to-wit:

     The Northeasterly 200 feet of Block Forty-One (41) St. Vincent's
     Addition Second Filing, also described as: Beginning at the most
     Northerly corner of Block Forty-One (41) St. Vincent's Addition Second
     Filing and running thence Southwesterly along the Northwesterly
     boundary line of the Block, 200 feet; Thence Southeasterly at right
     angles along the Northeasterly boundary line of Lots Nine (9) and
     Fifty-Six (56), 266 feet to the Southeasterly boundary line of Block
     Forty-One (41); Thence Northeasterly along said Southeasterly boundary
     line, 200 feet to the Northeasterly boundary line of Block Forty-One
     (41); Thence Northwesterly at right angles along the Northeasterly
     boundary line of Block Forty-One (41), 266 feet to the point of
     beginning; TOGETHER WITH AN EASEMENT OVER THE NORTHEASTERLY 12.5 FEET
     OF LOT FIFTY-SIX (56), BLOCK FORTY-ONE (41), ST. VINCENT'S ADDITION
     SECOND FILING, AS DESCRIBED IN INSTRUMENT RECORDED IN BOOK 6834 AT
     PAGE 570 IN THE OFFICE OF THE COUNTY CLERK AND RECORDER IN AND FOR THE
     CITY AND COUNTY OF DENVER, COLORADO.



<PAGE>
Rider to Sublease dated as of April 16, 1990 between General Motors Corporation
and Water Products Company

25.  ENVIRONMENTAL HOLD HARMLESS. Sublessee indemnifies and holds Sublessor
harmless from any loss, expense, liability, or damage, excluding consequential
damages such as loss of profit or business opportunity (hereinafter "Claims")
due to any environmental contamination which occurs on the Premises as a result
of Sublessee's acts or omissions during the term, and any extensions thereto, of
this Sublease Agreement which results in liability being imposed by a
governmental agency or alleged by a third party; provided, however, that in no
event shall Sublessee be responsible for any environmental contamination which
occurred on the Premises prior to, or which occurs after, Sublessee's tenancy.
Sublessor indemnifies and holds Sublessee harmless from any Claims due to
environmental contamination which occurred on the Premises prior to the term of
this Sublease Agreement, including specifically any such contamination related
to the underground storage tanks which were removed prior to the term hereof,
which results in liability being imposed by a governmental agency or alleged by
a third party.