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Water Budget Irrigation Rates

The City of Santa Barbara (as of July 1, 2013) uses tiered water rates for your dedicated irrigation meter, based on meeting your landscape’s assigned water budget. Effectively managing the right amount of water for your landscape takes calculation, measurement, and active management. The best way to do this is through a landscape water budget where the amount of water for your landscape is calculated and assigned based on the type of plants, size of irrigated area, and changes in weather. Click here to watch a video about Water Budget Irrigation Rates.

How Are the Water Budget Irrigation Rates Calculated?

Tier 1 allotment is based on the monthly water budget, which is determined by the property’s irrigated landscaped area and the monthly watering needs of your plants. The purpose of providing a monthly water budget is to bill based on the water needs of your landscaping and current weather conditions. Each account has a different water budget based on the type of plants and size of irrigated area, which will vary monthly based on changes in weather.

How Am I Billed?

No matter what your water budget is, you are only billed for the water you use. If your usage is below the monthly budget level, all use will be billed at your Tier 1 rate. However, if your usage exceeds the monthly water budget, all use above the budgeted amount is billed at the Tier 2 rate.

Water Budget Formula Parameters

Tier 1

Tier 2


(Hydrozone Area)


(Plant Factor)


(Irrigation Efficiency)

All Use within Monthly Budget (per HCF)

All other Use

(per HCF)

Irrigation - Agriculture






Irrigation - Recreation








Irrigation - Urban (Residential/Commercial)



Turf *





* Maximum Irrigated Areas apply for Turf on Urban Irrigation accounts, as follows:

  • Residential Turf Area cannot exceed 20% of Total Irrigated Area
    • If measurements are greater than 20% of total, the remainder square footage will be assigned to the Irrigated Shrub Area.
  • Commercial Turf Area = 0% of Total Irrigated Area
    • If irrigated turf area exists, it will be assigned to the Irrigated Shrub Area.
  • Plant Factor % allotments reflect the requirements of City’s Landscape Design Standards, SBMC 22.80.

How is My Irrigated Area Determined?

Your landscape’s assigned water budget is based on City measurement records of your irrigated area. If this amount seems inaccurate, call (805) 564-5460 immediately to schedule a groundtruthing of your site’s irrigated area. The City will also be selecting sites for groundtruthing if it appears the City’s current records are inaccurate. Your account may be subject to mandatory groundtruthing measurement to verify the accuracy of measured irrigated area and plant types.

How is My Water Budget Calculated?

The Monthly Water Budget equation includes reference evapotranspiration (ETo) data from a local weather station, plant factors that relate plant type water use needs, and irrigated areas of turf and shrubs.   Tier 1 is determined monthly using the following formula:

Monthly Water Budget Tier 1 = (ETo)(.62/748)((PF x HA)/IE))

  • ETo = Reference evapotranspiration (weather factor)
  • 0.62/748 = Conversion factor (inches to HCF)
  • PF = Plant factor
  • HA = Hydrozone Area = Square footage of irrigated area(s), by plant type (turf or shrubs)
  • IE = Irrigation efficiency (80%)

It is the input of the ETo data that causes the Monthly Water Budget to fluctuate.  All other parameters will stay the same, unless changes are made to landscaping and reported to the City.

ETo Data

Evapotranspiration (ETo) is the loss of water to the atmosphere by the combined processes of evaporation (from soil and plant surfaces) and transpiration (from plant tissues). It is an indicator of how much water your shrubs, lawn, and trees need for healthy growth and productivity. ETo is measured by a combination of solar radiation level, wind speed, humidity, and temperature. The City will use real-time ETo data by downloading monthly ETo data from a weather station located in Santa Barbara. 

To obtain ETo data to determine your water budget, sign up for a free CIMIS account here.

How Do I Determine How Much to Irrigate to Stay Within My Water Budget?

In order to properly manage the irrigation water on your site to stay within your landscape water budget, you are encouraged to use the resources below. These will help you determine how to water your landscaping efficiently each month:

- Get a free water checkup to review your sprinkler timer schedule and how to schedule for efficiency.
- Use the Watering Calculator and Weekly Watering % Adjust.
- Upgrade your sprinkler timer to a Smart Irrigation Controller (rebates available)
- Encourage your landscaper to manage your landscape to a budget. Two tools landscaper can use: 
        - CLCA Certified Water Management Program online reporting. (If your landscaper is not certified, send them through the training or hire one that has.)
        - Sign up for our online Landscape Budgets Program by contacting us for a username and password to get started.

Last Updated: Feb 28, 2020
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