Document:

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                                                                   Exhibit 10.15

                                           CUSTOMER REFERENCE: 00000001305680

DATE OF AMENDMENT: FEBRUARY 6, 2003        AMENDMENT TO LETTER OF CREDIT NO.:
                                           1S1305680
                                           DATE OF ISSUE: JANUARY 23, 2002

ISSUING BANK:                              APPLICANT:
FLEET NATIONAL BANK                        WATTS INDUSTRIES, INC.
C/O GLOBAL TRADE OPERATIONS                815 CHESTNUT ST,
1 FLEET WAY, MAIL STOP: PAEH0802SM         NORTH ANDOVER, MA 01845
SCRANTON PA 18507-1999

                                           BENEFICIARY:
                                           ACE PROPERTY AND CASUALTY INSURANCE
                                           COMPANY AND PACIFIC EMPLOYERS'
                                           INSURANCE COMPANY
                                           1601 CHESTNUT ST.
                                           PHILADELPHIA, PA. 19103-0000
                                           ATTN: COLLATERAL MANAGER

THE ABOVE MENTIONED CREDIT IS AMENDED AS FOLLOWS:

THE AMOUNT OF THIS CREDIT HAS BEEN INCREASED BY USD 7,258,550.00
THE AMOUNT OF THE CREDIT ISSUED NOW TOTALS USD 11,770,000.00

ALL CORRESPONDENCE INCLUDING PRESENTATIONS UNDER THIS LETTER OF CREDIT SHALL BE
SENT TO FLEET NATIONAL BANK, ATTN: GLOBAL TRADE OPERATIONS DEPT., STANDBY UNIT,
1 FLEET WAY, SCRANTON, PA 18507.

ALL OTHER TERMS AND CONDITIONS REMAIN UNCHANGED.

                                                   /s/ [ILLEGIBLE]
                                                   --------------------
                                                   AUTHORIZED SIGNATURE

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                                      STANDBY LETTER OF CREDIT NO. 1S1305680
                                      DATE OF ISSUE:  JANUARY 23, 2002

ISSUING BANK:                         APPLICANT:
FLEET NATIONAL BANK                   WATTS INDUSTRIES, INC.
C/O GLOBAL TRADE OPERATIONS           815 CHESTNUT ST.
1 FLEET WAY, MAIL STOP: PAEH0802SM    NORTH ANDOVER, MA 01845
SCRANTON PA 18507-1999

                                      BENEFICIARY:
                                      ACE PROPERTY AND CASUALTY INSURANCE
                                      COMPANY AND PACIFIC EMPLOYERS'
                                      INSURANCE COMPANY
                                      1601 CHESTNUT ST.

                                             AND

                                      PHILADELPHIA, PA. 19103-0000
                                      ATTN: COLLATERAL MANAGER

                                      AMOUNT/CURRENCY:
                                      USD 4,511,450.00
                                      FOUR MILLION FIVE HUNDRED ELEVEN THOUSAND
                                      FOUR HUNDRED FIFTY AND 00/100'S US
                                      DOLLARS

                                      DATE AND PLACE OF EXPIRY:
                                      DECEMBER 31, 2002 AT OUR COUNTERS

GENTLEMEN:

BY ORDER OF OUR CLIENT, WATTS INDUSTRIES, INC., WE HEREBY ESTABLISH THIS
IRREVOCABLE LETTER OF CREDIT NO. 1S1305680 IN YOUR FAVOR FOR AN AMOUNT UP TO BUT
NOT EXCEEDING THE AGGREGATE SUM OF FOUR MILLION FIVE HUNDRED ELEVEN THOUSAND
FOUR HUNDRED FIFTY AND 00/100 U.S. DOLLARS (U.S. $4,511,450.00), EFFECTIVE
IMMEDIATELY, AND EXPIRING AT THE OFFICES OF THE BANK ON DECEMBER 31, 2002,
UNLESS RENEWED AS HEREINAFTER PROVIDED.

THE TERM "BENEFICIARY" INCLUDES ANY SUCCESSOR BY OPERATION OF LAW OF THE NAMED
BENEFICIARY INCLUDING, WITHOUT LIMITATION, ANY LIQUIDATOR, REHABILITATOR,
RECEIVER OR CONSERVATOR.

FUNDS UNDER THIS LETTER OF CREDIT ARE AVAILABLE TO YOU AGAINST YOUR SIGHT
DRAFT(S), DRAWN ON US, BEARING THE CLAUSE: "DRAWN UNDER CREDIT NO. 1S1305680".

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 THIS IS AN INTEGRAL PART OF LETTER OF CREDIT NUMBER: 1S1305680

THIS LETTER OF CREDIT WILL BE AUTOMATICALLY RENEWED FOR A ONE YEAR PERIOD UPON
THE EXPIRATION DATE SET FORTH ABOVE AND UPON EACH ANNIVERSARY OF SUCH DATE,
UNLESS AT LEAST SIXTY (60) DAYS PRIOR TO SUCH EXPIRATION DATE, OR PRIOR TO ANY
ANNIVERSARY OF SUCH DATE, WE NOTIFY BOTH YOU AND YOUR CLIENT IN WRITING BY
REGISTERED MAIL THAT WE ELECT NOT TO SO RENEW THIS LETTER OF CREDIT.

UPON RECEIPT BY YOU OF OUR NOTICE OF ELECTION NOT TO RENEW THIS LETTER OF
CREDIT, YOU MAY DRAW HEREUNDER BY YOUR SIGHT DRAFT(S) DRAWN ON US AND BEARING
THE CLAUSE: "DRAWN UNDER CREDIT NO. 1S1305680".

THIS LETTER OF CREDIT SETS FORTH IN FULL THE TERMS OF OUR UNDERTAKING. SUCH
UNDERTAKING SHALL NOT IN ANY WAY BE MODIFIED, AMENDED OR AMPLIFIED BY REFERENCE
TO ANY DOCUMENT OR INSTRUMENT REFERRED TO HEREIN OR IN WHICH THIS LETTER OF
CREDIT IS REFERRED TO OR TO WHICH THIS LETTER OF CREDIT RELATES AND ANY SUCH
REFERENCE SHALL NOT BE DEEMED TO INCORPORATE HEREIN BY REFERENCE ANY DOCUMENT OR
INSTRUMENT.

ALL BANK CHARGES AND COMMISSIONS INCURRED IN THIS TRANSACTION ARE FOR THE
APPLICANT'S ACCOUNT.

WE HEREBY AGREE WITH THE DRAWERS, ENDORSERS AND BONA FIDE HOLDERS OF DRAFTS
DRAWN UNDER AND IN COMPLIANCE WITH THE TERMS OF THIS CREDIT THAT SUCH DRAFTS
WILL BE DULY HONORED UPON PRESENTATION TO THE DRAWEE. THE OBLIGATION OF FLEET
NATIONAL BANK UNDER THIS LETTER OF CREDIT IS THE INDIVIDUAL OBLIGAITON OF FLEET
NATIONAL BANK, AND IS IN NO WAY CONTINGENT UPON REIMBURSEMENT WITH RESPECT
THERETO.

EXCEPT AS OTHERWISE EXPRESSLY STATED HEREIN, THIS CREDIT IS SUBJECT TO AND
GOVERENED BY THE LAWS OF THE STATE OF NEW YORK AND THE 1993 REVISION OF THE
UNIFORM CUSTOMS AND PRACTICE FOR DOCUMENTARY CREDITS OF THE INTERNATIONAL
CHAMBER OF COMMERCE (PUBLICATION 500) AND, IN THE EVENT OF ANY CONFLICT, THE
LAWS OF THE STATE OF NEW YORK WILL CONTROL. IF THIS CREDIT EXPIRES DURING AN
INTERRUPTION OF BUSINESS AS DESCRIBED IN ARTICLE 17 OF SAID I.C.C. PUBLICATION,
WE AGREE TO EFFECT PAYMENT IF THIS CREDIT IS DRAWN AGAINST WITHIN 30 DAYS AFTER
THE RESUMPTION OF BUSINESS.

                                                   /s/ [ILLEGIBLE]
                                                   --------------------
                                                   AUTHORIZED SIGNATURE

                      THIS DOCUMENT CONSISTS OF 2 PAGE(S).<Page>

                                                                 EXHIBIT  10.16

                                 THIRD AMENDMENT
                                       TO
                  REVOLVING CREDIT AGREEMENT AND LIMITED WAIVER

      Third Amendment and Limited Waiver dated as of December 16, 2003 to
Revolving Credit Agreement (the "THIRD AMENDMENT"), by and among WATTS REGULATOR
CO., a Massachusetts corporation (the "DOMESTIC BORROWER"), WATTS INDUSTRIES
EUROPE B.V., a private company with limited liability organized under the laws
of The Netherlands (the "FOREIGN BORROWER", and together with the Domestic
Borrower, the "BORROWERS" and each individually, a "BORROWER"), and FLEET
NATIONAL BANK and the other lending institutions listed on SCHEDULE 1 to the
Credit Agreement (as hereinafter defined) (the "LENDERS"), amending certain
provisions of the Revolving Credit Agreement dated as of February 28, 2002 (as
amended and in effect from time to time, the "CREDIT AGREEMENT") by and among
the WATTS WATER TECHNOLOGIES, INC. (F/K/A WATTS INDUSTRIES, INC.), a Delaware
corporation (the "PARENT"), the Borrowers, the Lenders, and FLEET NATIONAL BANK
in its capacity as administrative agent for the Lenders (the "ADMINISTRATIVE
AGENT"). Terms not otherwise defined herein which are defined in the Credit
Agreement shall have the same respective meanings herein as therein.

      WHEREAS, the Borrowers and the Lenders have agreed to modify certain terms
and conditions of the Credit Agreement and waive certain terms of the Credit
Agreement, in each case as specifically set forth in this Third Amendment;

      NOW, THEREFORE, in consideration of the premises and the mutual agreements
contained herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto hereby agree as
follows:

      SECTION 1. AMENDMENT TO SECTION 1 OF THE CREDIT AGREEMENT. Section 1 of
the Credit Agreement is hereby amended by inserting the following definitions
in the following alphabetical order:

            DECEMBER CLASS A OFFERING. That certain Equity Issuance consisting
      of the underwritten public offering of approximately 4,600,000 shares of
      the Parent's Class A common stock consummated on or about December 16,
      2003 pursuant to which the Parent received Net Cash Equity Issuance
      Proceeds of approximately $82,400,000.

            WATTS FLOWMATIC. Watts Flowmatic, Inc., a Delaware corporation and
      wholly-owned Subsidiary of the Domestic Borrower.

      SECTION 2. AMENDMENT TO SECTION 3 OF THE CREDIT AGREEMENT. Section
3.2.2(b) of the Credit Agreement is hereby amended by inserting immediately
after the words "Net Cash Equity

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Issuance Proceeds in excess of $50,000,000 from Equity Issuances" a comma and
the words "other than the Net Cash Equity Issuance Proceeds received in
connection with the December Class A Offering".

      SECTION 3. AMENDMENT TO SECTION 7 OF THE CREDIT AGREEMENT. Section 7.15
of the Credit Agreement is hereby amended by inserting immediately at the end of
the first sentence thereof a semicolon and the words "PROVIDED, HOWEVER,
notwithstanding the foregoing, the Parent shall not be required to cause Watts
Flowmatic to become a Guarantor hereunder, and otherwise comply with the
provisions of this Section 7.15(a), until February 15, 2004".

      SECTION 4. LIMITED WAIVER. Pursuant to Section 7.14 of the Credit
Agreement, if, after the Closing Date, the Parent or any of its Subsidiaries
creates or acquires, either directly or indirectly, any Subsidiary, it will
promptly (but in any event no later than five (5) days after such creation or
acquisition) notify the Administrative Agent of such creation or acquisition, as
the case may be, and provide the Administrative Agent and the Lenders with an
updated SCHEDULE 6.18(a) thereto. Martin Orgee UK Ltd. became a Subsidiary on
April 18, 2003, Giuliani Anello S.r.l became a Subsidiary on July 30, 2003, and
Watts Flowmatic became a Subsidiary on November 19, 2003 (each such event being
hereinafter referred to as a "SUBSIDIARY CREATION EVENT" and the date on which
such Subsidiary became a Subsidiary being hereinafter referred to as a
"SUBSIDIARY CREATION DATE"). To the extent the Parent or any Subsidiary failed
to notify the Administrative Agent and the Lenders of each such creation or
acquisition as required by Section 7.14 of the Credit Agreement and failed to
provide the Administrative Agent and the Lenders with an updated SCHEDULE
6.18(a), the Administrative Agent and the Lenders hereby waive such notice and
delivery requirements of Section 7.14 of the Credit Agreement, retroactive to
each applicable Subsidiary Creation Date, but only as it pertains to each such
Subsidiary Creation Event (and not any other creation or acquisition of any
other Subsidiary) and only to the extent that the Administrative Agent receive
the updated SCHEDULE 6.18(a) referred to in Section 5 below. Nothing contained
herein shall be construed as a willingness on the part of the Administrative
Agent or the Lenders to grant any similar waivers in the future.

      SECTION 5. CONDITIONS TO EFFECTIVENESS. This Third Amendment shall not
become effective until the Administrative Agent receives the following:

      (a) a counterpart of this Third Amendment, executed by the Borrowers, the
Required Lenders and the Guarantors; and

      (b) an updated Schedule 6.18(a), which schedule accurately reflects all
Subsidiaries of the Parent, together with the jurisdiction of
incorporation/formation and principal place of business or registered office of
each such Subsidiary.

      SECTION 6. REPRESENTATIONS AND WARRANTIES. Each Borrower hereby repeats,
on and as of the date hereof, each of the representations and warranties made by
it in [Section]6 of the Credit Agreement (except to the extent of changes
resulting from transactions contemplated or permitted by the Credit Agreement
and the other Loan Documents and changes occurring in the ordinary course of
business that singly or in the aggregate are not materially adverse, and to the
extent that such representations and warranties relate expressly to an earlier
date), PROVIDED, that all references therein to the Credit Agreement shall refer
to such Credit

                                       2
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Agreement as amended hereby. In addition, each Borrower hereby
represents and warrants that the execution and delivery by such Borrower of this
Third Amendment and the performance by such Borrower of all of its agreements
and obligations under the Credit Agreement as amended hereby are within the
authority of such Borrower and have been duly authorized by all necessary action
on the part of such Borrower.

      SECTION 7. RATIFICATION, ETC. Except as expressly amended hereby, the
Credit Agreement , the other Loan Documents (which, for the avoidance of doubt,
shall included the Guaranties) and all documents, instruments and agreements
related thereto are hereby ratified and confirmed in all respects and shall
continue in full force and effect. The Credit Agreement and this Third Amendment
shall be read and construed as a single agreement. All references in the Credit
Agreement or any related agreement or instrument to the Credit Agreement shall
hereafter refer to the Credit Agreement as amended hereby.

      SECTION 8. NO WAIVER. Nothing contained herein shall constitute a waiver
of, impair or otherwise affect any Obligations, any other obligation of the
Borrowers or any rights of the Administrative Agent or the Lenders consequent
thereon.

      SECTION 9. COUNTERPARTS. This Third Amendment may be executed in one or
more counterparts, each of which shall be deemed an original but which together
shall constitute one and the same instrument.

      SECTION 10. GOVERNING LAW. THIS THIRD AMENDMENT SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS
(WITHOUT REFERENCE TO CONFLICT OF LAWS).

                                       3

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      IN WITNESS WHEREOF, the parties hereto have executed this Third Amendment
as a document under seal as of the date first above written.

                     WATTS REGULATOR CO.

                     By: /s/ WILLIAM C. MCCARTNEY
                         ------------------------------------
                            Name: William C. McCartney
                            Title:  Chief Financial Officer

                     WATTS INDUSTRIES EUROPE B.V.

                     By: /s/ JOHAN VAN KOUTERIK
                         ------------------------------------
                            Name: Johan van Kouterik
                            Title:  Finance Director

                     FLEET NATIONAL BANK

                     By: /s/ CHRISTOPHER J. WICKLES
                         ------------------------------------
                            Name: Christopher J. Wickles
                            Title:  Director

                     BANK OF AMERICA, N.A.

                     By: /s/ JONATHAN M. PHILLIPS
                         ------------------------------------
                            Name: Jonathan M. Phillips
                            Title:  Vice President

                     CITIZENS BANK OF MASSACHUSETTS

                     By: /s/ STEPHANIE EPKINS
                         ------------------------------------
                            Name: Stephanie Epkins
                            Title:  Vice President

                                       4

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                     MELLON BANK, N.A.

                     By: _________________________________
                            Name:
                            Title:

                     WACHOVIA BANK, NA SUCCESSOR TO FIRST UNION NATIONAL BANK

                     By: /s/ SARAH T. WARREN
                         ---------------------------------
                            Name: Sarah T. Warren
                            Title:  Director

                     BROWN BROTHERS HARRIMAN & CO.

                     By: ________________________________
                            Name:
                            Title:

                     JPMORGAN CHASE BANK

                     By: /s/ A. NEIL SWEENEY
                         --------------------------------
                            Name: A. Neil Sweeney
                            Title:  Vice President

                     KEYBANK NATIONAL ASSOCIATION

                     By: /s/ THOMAS J. PURCELL
                         --------------------------------
                            Name: Thomas J. Purcell
                            Title:  Senior Vice President

                                       5

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                            RATIFICATION OF GUARANTY

         Each of the undersigned guarantors (the "GUARANTORS") hereby
acknowledges and consents to the foregoing Third Amendment as of December 16,
2003, and agrees that each of (a) the Guaranty dated as of February 28, 2002
from the Parent and each Domestic Subsidiary; (b) the Guaranty dated as of
February 28, 2002 from Watts Ocean B.V.; (c) the Guaranty dated as of February
28, 2002 from Watts Cazzaniga Spa; (d) the Guaranty dated as of April 22, 2002
from Watts Intermes Srl and (e) the Guaranty dated as of June 30, 2002 from
Hunter Innovations, Inc. remains in full force and effect, and each such
Guarantor confirms and ratifies all of its obligations thereunder.

                      WATTS WATER TECHNOLOGIES, INC.

                      By: /s/ WILLIAM C. MCCARTNEY
                             Title: Chief Financial Officer

                      WATTS PREMIER, INC.

                      By: /s/ WILLIAM C. MCCARTNEY
                          ----------------------------------
                             Title:

                      WATTS SPACEMAKER, INC.

                      By: /s/ WILLIAM C. MCCARTNEY
                          ----------------------------------
                             Title:

                      WATTS RADIANT, INC.

                      By: /s/ WILLIAM C. MCCARTNEY
                          ----------------------------------
                             Title:

                      ANDERSON-BARROWS METALS CORPORATION

                      By: /s/ WILLIAM C. MCCARTNEY
                          ----------------------------------
                             Title:

                                       6

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                      WATTS DRAINAGE PRODUCTS, INC.

                      By: /s/ WILLIAM C. MCCARTNEY
                          ----------------------------------
                              Title:

                       WEBSTER VALVE, INC.

                       By: /s/ WILLIAM C. MCCARTNEY
                           ----------------------------------
                              Title:

                       WATTS DISTRIBUTION COMPANY, INC.

                       By: /s/ WILLIAM C. MCCARTNEY
                           ----------------------------------
                              Title:

                       JAMECO INDUSTRIES, INC.

                       By: /s/ WILLIAM C. MCCARTNEY
                           ----------------------------------
                              Title:

                       WATTS OCEAN B.V.

                       By: /s/ JOHAN VAN KOUTERIK
                           ----------------------------------
                              Title: Director

                                       7

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                       WATTS CAZZANIGA SPA

                       By: /s/ JOHAN VAN KOUTERIK
                           ----------------------------------
                              Title:  Director

                       WATTS INTERMES SRL

                       By: /s/ JOHAN VAN KOUTERIK
                           ----------------------------------
                              Title:  Director

                       HUNTER INNOVATIONS, INC.

                       By: /s/ WILLIAM C. MCCARTNEY
                           ----------------------------------
                              Title:

                                       8

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