<PAGE>

                                                                   Exhibit (4.4)

                                                               Boxes not checked
                                                               are inapplicable.

                                  BUSINESS NOTE
                      (Use only for business purpose loans)

BADGER METER, INC.
(MAKER)

[Check (a), (b), (c) or (d); only one shall apply.]
(a)  [ ]  SINGLE PAYMENT. In one payment on N/A, plus interest payable as set
          forth below unless interest is shown on line 4 at the bottom of this
          Note.
(b)  [X]  INSTALLMENTS OF PRINCIPAL AND INTEREST. In 36 equal payments of $
          478,743.95 due on January 30,2004 and on [X] the same day(s) of each
          CONSECUTIVE month thereafter [ ] every 7th day thereafter [ ] every
          14th day thereafter, with the final payment of the unpaid balance and
          accrued interest due on December 30, 2006, all subject to modification
          as set forth in 2(b) below, if applicable. All payments include
          principal and interest.
(c)  [ ]  INSTALLMENTS OF PRINCIPAL. In N/A equal payments of principal of $ N/A
          due on N/A and on [ ] the same day(s) of each N/A month thereafter [ ]
          every 7th day thereafter [ ] every 14th day thereafter, PLUS a final
          payment of the unpaid principal due on N/A, PLUS interest payable as
          set forth below.
(d)  [ ]  OTHER. N/A

2.   INTEREST CALCULATION. If the amount of interest is not shown on line 4
     below, this Note bears interest on the unpaid principal balance before
     maturity:

     [Check (a) or (b) or complete line 4 below; only one shall apply.]
(a)  [X]  FIXED RATE.  At the rate of 4.809% per year.
(b)  [ ]  VARIABLE RATE. At the annual rate which is equal to the following
          Index Rate, [ ] plus [ ] minus N/A percentage points ("Note Rate"),
          and the Note Rate shall be adjusted as provided below. The Index Rate
          is:
     [ ]  The prime rate [ ] The reference rate [ ] The base rate adopted by [ ]
          lender [ ] N/A from time to time as its base or reference rate for
          interest rate determinations. The Index Rate may or may not be the
          lowest rate charged by lender.
     [ ]  N/A

          The initial Note Rate is N/A% per year and shall not at any time be
          less than N/A% per year. An adjustment in the Note Rate will result in
          an increase or decrease in (1) [ ] the amount of each payment of
          interest, (2) [ ] the amount of the final payment, (3) [ ] the number
          of scheduled periodic payments sufficient to repay this Note in
          substantially equal payments, (4) [ ] the amount of each remaining
          payment of principal and interest so that those remaining payments
          will be substantially equal and sufficient to repay this Note by its
          scheduled maturity date, (5) [ ] the amount of each remaining payment
          of principal and interest (other than the final payment) so that those
          remaining payments will be substantially equal and sufficient to repay
          this Note by its scheduled maturity date based on the original
          amortization schedule used by Lender, plus the final payment of
          principal and interest, or (6) [ ] N/A In addition, Lender is
          authorized to change the amount of periodic payments if and to the
          extent necessary to pay in full all accrued interest owing on this
          Note. The Maker agrees to pay any resulting payments or amounts. The
          Note Rate shall be adjusted only on the following change dates: [ ]
          the first day of each month [ ] each scheduled payment date [ ] as and
          when the Index Rate changes [ ] N/A

Interest is computed:
(c)  [X]  For the actual number of days principal is unpaid on the basis of [X]
          a 360 day year [ ] a 365 day year.
(d)  [ ]  For the number of days principal is unpaid on the basis of a 360 day
          year, counting each day as 1/30th of a month and disregarding
          differences in lengths of months and years. Unpaid principal and
          interest bear interest after maturity until paid (whether by
          acceleration or lapse of time) at the rate [X] which would otherwise
          be applicable plus 3 percentage points [ ] of N/A% per year, computed
          on the same basis as the interest rate before maturity.

3.   INTEREST PAYMENT. Interest is payable on N/A, and on [ ] the same day of
     each N/A month thereafter, [ ] every 7th day thereafter, [ ] every 14th day
     thereafter, and at maturity, or, if box 1(b) is checked, at the times so
     indicated.


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4.   OTHER CHARGES. If any payment (other than the final payment) is not made on
     or before the 10TH day after its due date, Lender may collect a delinquency
     charge of 5% of the unpaid amount. Maker agrees to pay a charge of $ 15.00
     for each check presented for payment under this Note which is returned
     unsatisfied.

5.   PREPAYMENT. Full or partial prepayment of this Note [ ] is permitted at any
     time without penalty {X} SEE ATTACHED EXHIBIT A FOR PREPAYMENT PENALTY. IN
     THE EVENT THIS NOTE IS RENEWED, A LOAN ADMINISTRATION FEE MAY BE ASSESSED.

            THIS NOTE INCLUDES ADDITIONAL PROVISIONS ON REVERSE SIDE.


                                        BADGER METER. INC.                (SEAL)
                                        CORPORATION
                                        ----------------------------------------
                                        (Type of organization)


                                    By: /s/ Richard A. Meeusen            (SEAL)
                                        ----------------------------------------


                                    By: /s/ Richard E. Johnson            (SEAL)
                                        ----------------------------------------




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<PAGE>

December 29, 2003


Mr. James P. McMullen
Vice President
M&I Marshall & Ilsley Bank
770 North Water Street
Milwaukee, Wisconsin

Dear Mr. McMullen:

The undersigned covenants that as long as any obligation is owed M&I Marshall &
Ilsley Bank, ("Lender") under the terms and conditions of a promissory note
dated December 29, 2003 in the amount of $16.000.000, (the "Note"), and all
extensions, renewals or modifications of the Note, the undersigned will not sell
or encumber in any of its assets and all obligations to Lender shall become due
and payable upon the sale, lease or other disposition of the assets of Badger
Meter, Inc.

A breach of this covenant shall constitute an additional event of default under
the Note and Lender may, at its option, declare the Note due and payable, and
may pursue all remedies available to it with regard to the Note. The undersigned
shall reimburse Lender for all expenses incurred by it in protecting or
enforcing its rights under this letter agreement, including without limitation
reasonable attorneys' fees and legal expenses.

Dated this 29th day of December, 2003.


Badger Meter, Inc.


By:    /s/ Richard A. Meeusen
       ----------------------------------------

Title: President/CEO
       ----------------------------------------



By:    /s/ Richard E. Johnson
       ----------------------------------------

Title: Senior V.P. Finance, CFO & Treasurer
       ----------------------------------------


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PREPAYMENT FEE OPTIONS

Standard
--------

YIELD MAINTENANCE - LIBOR/Swap
The Yield Maintenance Fee, as hereinafter provided, shall be immediately due and
payable by Maker upon a full or partial prepayment of this Note at any time
prior to the final scheduled payment due date on the Note.

Yield Maintenance Fee: "Yield Maintenance Fee" means an amount equal to the
excess, if any, of the amount of:

     (i)  monthly interest which would otherwise be payable on the prepaid
          principal amount of this Note from the date of prepayment through the
          final schedule payment due date on the Note, over the

     (ii) monthly interest Lender would earn if the prepaid principal amount
          were reinvested for the period from the date of prepayment through the
          final scheduled payment due date on the Note, at the Reinvestment Rate
          (as hereinafter defined) plus 1.50%,

Such difference shall be discounted to present value at the Reinvestment Rate.

REINVESTMENT RATE: If the remaining term of the Note is less than one year,
"Reinvestment Rate" means: the yield in percent per annum on Eurodollar Deposits
(London) as of the Reinvestment Rate Determination Date (as hereinafter defined)
which has a maturity equal to the remaining term of the Note;
if the remaining term of the Note is one year or more, "Reinvestment Rate"
means: the yield in percent per annum on Interest Rate Swaps as of the
Reinvestment Rate Determination Date which has a maturity equal to the remaining
term of the Note; or,
in the event there is no rate available for a term that is equal to the
remaining term of the Note, "Reinvestment Rate" means: the linearly interpolated
yield between the two yields (Eurodollar Deposits and/or Interest Rate Swaps, as
applicable), one for the closest maturity less than the remaining term of the
Note, and the other for the closest maturity greater than the remaining term of
the Note.

REINVESTMENT RATE DETERMINATION DATE: "Reinvestment Rate Determination Date"
means the date which is five (5) banking days prior to the scheduled prepayment
date.

PUBLISHED YIELDS: Yields on Eurodollar Deposits (London) and Interest Rate Swaps
shall be the applicable rates available and published most recently by the Board
of Governors of the Federal Reserve System as of such Reinvestment Rate
Determination Date.

(Release H.15, available at www.federalreserve.gov/releases/h15/update)

PREPAYMENT CALCULATION NOTICE TO MAKER: Promptly after the Reinvestment Rate
Determination Date, Lender shall notify Maker of the amount and the basis of
determination of the required Yield Maintenance Fee, and such determination and
amount shall be binding on both parties absent manifest error.


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