Water Meters
Rate structures and allocations for non-residential customers are individualized according to past usage. The Town calculates the customer's average monthly usage historically, then sets the allocation at twice that amount.

Tier 1 - The customer's individualized, budgeted amount
Tier 2 - Usage over the budgeted amount

Leaky or broken water pipes, inefficient watering practices and malfunctioning irrigation systems can lead to excessive usage. Customers who exceed their first tier allocation are encouraged to contact the water conservation division to discuss ways to enhance efficiency.

Customers who require more water because they are changing their type of business or expanding operations may contact the division to adjust their water allocation.

All homeowner associations, multi- family residential and commercial customers with automatic irrigation systems drawing water from a water meter must obtain a permit from the Inspections and Permits Department to remove their watering system from the water meter and re-install it using a separate irrigation meter.

Irrigation Meters
Town staff has created site-specific water budgets for all non-single-family residential separately metered irrigation customers. These water budgets are an upper bound estimate of the water needed to efficiently irrigate a site based on the amount of landscaped area, evapotranspiration rate, and necessary adjustment factors.

The amount of water calculated for a customer is considered the upper limit of their first tier. Any usage exceeding the budgeted amount falls into the second tier and is billed at the second tier rate.

Water Budget Formula

The Town of Cary water budget is based on the California Urban Water Conservation Council, BMP 5. The formula for this method is: Water Use Budget = Landscaped Area * Conversion Factor * ((Eto * Kl) - Effective Rainfall) * 1/ Irrigation Efficiency)

• Landscaped Area
  Staff determines area size by digitizing aerial photos of the property, measuring the site, and analyzing the landscaped area.
• Conversion Factor
  Number that converts square feet into gallons
• Evapotranspiration (Eto)
  "The evapotranspiration process is the combination of two separate processes whereby water evaporates from the soil surface or from the crop surface (i.e., intercepted water or dew) and water that is transpired to the atmosphere from plants" (Irrigation Association, The Et Connection).
• Crop Coefficient (Kl)
  A crop coefficient is needed in order to relate potential evapotranspiration to a specific crop. Based on research findings from NC State University and to encourage the planting of warm season turf, a turf coefficient of .8 is used.
• Effective Rainfall
  Effective rainfall is, "The depth of rainfall in offsetting Eto during a billing period" (BMP 5 Handbook, California Urban Water Conservation Council).
• Irrigation Efficiency
  Since irrigation systems are not 100 percent efficient, the Town factors in an efficiency rate to account for a systems inability to distribute water uniformly. The Irrigation Association sets an efficiency rate of 62.5 percent. The Town of Cary uses an irrigation efficiency of 62.5 percent. To achieve that rate, the Town assumes that the system is periodically checked, properly designed, and appropriately maintained.

Contact the water conservation division to request an adjustment. The Town's Finance Department handles billing adjustments for leaks.