Wastewater/WMA Calculations

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For residential customers, wastewater is billed on the lower of either the winter month average (WMA) or the current month's water usage.

Wastewater is billed at 80% of water used for non-residential customers and residential customers who do not have a winter month average (WMA).

  • However, residential customers without a winter month average are not billed more than 12 thousand gallons for wastewater.

Each year, residential customers set the maximum amount for billing of wastewater for the next 12 months.

  • We take the water usage in the months of November, December, January and February to establish this average.  The months that this usage is billed are either November-February or December-March, depending on the meter reading dates.  We drop the month with the highest consumption.
  • The winter month's average is  based on a daily average.  This daily average will be used to determine the average use in an average month. 

Usage divided by number of days X 30.42 = WMA 

Month Usage Days *dropped-highest consumption
Nov

20

32

Dec

17

32

52/89 = 0.58
Jan

26*

28*

Feb

15

27

52

89

0.58 x 30.42 = 17.64

$17.64 is this customer's winter month average