Measuring Water and Sewer Service Affordability

Appendix 1: Computation of Residential Water and Wastewater Bills

Rate information was collected for all 110 out of 120 communities within GLWA. Rates were obtained from each city, town, township, or charter township via the internet or phone calls with local officials. Ten communities were not responsive to repeated phone calls, including Ash Township, Berlin Township, Commerce Township, Greenwood Township, Keego Harbor, Mayfield Township, Rockwood, Utica, Woodhaven, York Township. Burtchville Township was dropped because local officials indicated that most residents are not connected to the sewer system and many use private wells. These communities are noted with “no data” in tables and blank cells in maps.

Clayton Township and Genesee Township rates were obtained from water rates reported in 2014, then scaled by reported increases for 2015151 and 2016.152 Current rates were unavailable at the time of publication.

Average per capita water consumption in the United States is estimated to be between 2,400 and 3,000 gallons per month.153 Average usage for the GLWA service area was computed using monthly service volume within Detroit (the jurisdiction with the clearest reported monthly service volume) divided by the number of households and the average number of individuals per household.154 The resulting per capita estimate was 2,640 gallons per month, squarely within the national average. Total average household monthly usage given the average family size of 2.6155 is 6,864 gallons. This is roughly confirmed across GLWA, which reports average monthly usage for a family of three as 7,000 gallons.156

That monthly average was combined with individual community water rates per unit, wastewater rates per unit if applicable, fixed charges (water and wastewater), special charges (water and wastewater), and the number of billing periods per year to compute average annual bills broken out by water and wastewater. Because per-unit charges are reported by communities in varying units—gallons, hundred cubic feet (CCF), thousand cubic feet (MCF)—all units were converted to a common unit and prices were scaled accordingly. When billed by meter size, 5/8 connector (or smallest available) was chosen, as most residential meters are this size.

Economic Note: wholesale rates include fixed charges and per unit charges, so differences between community bills are a function of total wholesale volume and municipal markup. It is not possible with current data to disaggregate the proportion each influence has on the final retail cost.

  • 151. Dominic Adams, “Flint Monthly Water and Sewer Bills Highest in Genesee County by $35,” MLive, June 1, 2014, http://www.mlive.com/news/flint/index.ssf/2014/06/post_386.html.
  • 152. Jiquanda Johnson, “Genesee County Water Customers Will See Rate Increase Again This Year,” MLive, May 27, 2016, http://www.mlive.com/news/flint/index.ssf/2016/05/genesee_county_water_c....
  • 153. United States Geological Survey, “How Much Water Does the Average Person Use at Home Per Day?” Water Questions & Answers, USGS, last modified December 2, 2016, https://water.usgs.gov/edu/qa-home-percapita.html.
  • 154. It is possible, even likely, that average usage varies between urban areas such as Detroit and rural areas in the rest of GLWA. However, the point of this analysis is to identify differences in structural affordability of water according to local characteristics, not to compute actual water consumption across jurisdictions. The goal is comparability between locations, so a single usage estimate for all communities is required. Where the usage estimate comes from is less important than the variance in cost according to that usage estimate.
  • 155. Average household size calculated for GLWA service area based on American Community Survey 5-year estimates for 2016.
  • 156. GLWA, Eligibility Guidelines.