Wastewater/WMA Calculations


Your water meter measures your overall monthly water use, but there is no meter on your wastewater line. Traditionally, the three lowest water consumption months for residential accounts are the winter months when customers are not watering their lawns and water usage is mainly inside the house. The majority of the water used during winter months is entering the sanitary sewer. Therefore, the City determines your wastewater consumption by your winter month average (WMA); or if your current month’s water usage happens to be lower than your WMA, then the City will use the lower of the two consumption numbers to calculate your wastewater fee.

Usage divided by number of days X 30.42 = WMA

  • What about new residental customers who do not have a winter month average? Residents without a WMA are billed at 80% of the current month until the WMA is established. The maximum they will be billed is 12,000 gallons.
  • How do I lower the wastewater fee on my water bill? Each year, residential customers set the maximum amount for billing of wastewater for the next 12 months based on their winter month average (WMA). Conserving water during the wastewater averaging period (November through February) will lower the volume of wastewater you will be billed for each month for the next year. Updates to the WMAs are updated every April. View the High Water Bill FAQ page for more tips on controlling your water bill.
  • How is winter month average calculated? We average your water use in the months of November, December, January and February. The month with the highest consumption is dropped so that your winter month average is based on the three winter months with the lowest usage.
    Winter Month Average CalculationExample:
    Month Usage Days
    November 3 31
    December 3 25
    January 4 38*
    February 3 32
    Total 9 88
    *Dropped the month with the highest consumption.
    Divide Consumption by Days (9 / 88 = .10)
    Multiply .10 by the daily average multiplication number (.10 x 30.42), which equals the winter month average (3.04).