Storm Water Fees

What is an ERU?

The term ERU is an abbreviation for Equivalent Residential Unit. This term is used for water system planning to represent the water use (and pattern) of an average residential home. The definition of an ERU can vary from community to community and is supported by measured data. ERUs are calculated based on impervious surface with a residence counting as one (1) ERU.

Commercial development is assigned a number of ERUs based on impervious surface. One (1) ERU equals 3,000 square feet of impervious surface.

What is Impervious Surface?

Impervious surfaces are mainly artificial structures such as pavements, rooftops, sidewalks, roads, and parking lots - covered by impenetrable materials such as asphalt, concrete, brick, stone, or even compacted soils that seal the soil surface, eliminating rainwater infiltration and natural groundwater recharge.


  • Residential - $9 per month
  • Commercial - $9 per month per ERU
Commercial ERUs are calculated by the City Engineer and provided to the Utility Billing Department. If you have any questions regarding your ERU calculation, please call our Utility Billing Department at (801) 576-6504 or (801) 576-6512.