The City implemented tiered water rates to promote efficient water use, establish fair rates, and promote conservation of this precious resource.
The City of Corona Department of Water and Power implemented a tiered rate and water budget system in April, 2010. Tiered rates and water budgets are effective at promoting efficient water use and resource conservation. They provide enough water for typical but efficient water use indoors and outdoors. Tiered rates also provide a means to charge fair rates based on how water is being used. Inefficient water users will pay a higher cost for water than efficient water users.
How Your Water Budget Was Determined
Commercial customer budgets are based on a three year historical average of water use. Haven't been in business for three years? The first year of water service is at the budget rate. For the second year of service, the water budget is based on your usage during the first year.
Residential customers have an indoor and an outdoor budget. The calculation looks like this:
- Indoor Budget = (number of people x 55 gallons/person/day x number of days in the billing period)/748 gallons
- Outdoor Budget = (Irrigated Area x (ET/12) x OEF)/100
Questions? Contact Customer Care at (951) 736-2321 for more information on your budget calculations.
About the Indoor Budget
Your indoor budget is based on the number of people in your home. Each person is budgeted 55 gallons of water per day for each day in the billing period.
The American Water Works Association's (AWWA) 1997 study showed that on average, a person uses about 60 gallons of water each day indoors. The flows that come into the City's treatment plants confirmed that 60 gallons of water per day per person is accurate for Corona residents.
The number of residents in each home is based on the 2000 census that indicated Corona has an average of 3.4 residents per single-family residence. The City has chosen to use 4 as the standard.
About the Outdoor Budget
Your outdoor budget is the irrigated area, times the Evapotranspiration (ET) factor, times the Plant Factor (PF), divided by Irrigation Efficiency (IE).
- Structure or Mixed-Use Meter: Commercial customer budgets are based on a three year historical average of water use. Haven't been in business for three years? The first year of water service is at the budget rate. For the second year of service, the water budget is based on your usage during the first year.
- Dedicated Landscape or Reclaimed Meter: Outdoor Budget = (Irrigated Area x (ET/12) x OEF)/100
All residential customers have an indoor and an outdoor budget. The outdoor calculation looks like this: Irrigated Area x ETx PF/IE
Here's what those terms mean
Irrigation Area = the landscaped area. Calculated on GIS aerial data of landscaped areas and swimming pools are included in the irrigated area.
Evapotranspiration, or ET, is the amount of water that is lost each day due to evaporation and plant transpiration. Evaporation is water lost from the soil due to factors such as wind, humidity and temperature. Plant transpiration is the amount of water that plants lose from their leaves and plant tissues. Evapotranspiration is an indicator of how much water crops, lawns, gardens and trees need for healthy growth and productivity. By measuring evapotranspiration, only the amount of water that is lost will be put back into the soil, therefore reducing water waste. The evapotranspiration rate is measured on a daily basis, and is measured in inches. For your water budget, the ET for each day in the billing cycle is added up and used to calculate your outdoor budget. There is a higher evapotranspiration rate in the summer than in the winter, when the weather is warmer. Your budget will adjust each month to account for evapotranspiration, so your budget will be higher in the summer than in the winter. The ET data that Corona is using for the tiered rates comes from a CIMIS (California Irrigation Management Information System) weather station data located at UC Riverside. For more information on CIMIS, visit www.cimis.water.ca.gov.
Outdoor Efficiency Factor = the evapotranspiration factor for the types of plants being irrigated and gives a budget to accommodate efficient watering habits
Looking for ways to lower your water bill?
Check out our rebate and savings programs in the Conservation section.