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The Watering Index and Watering Calculator

Many of us overwater our plants and lawns. But now, figuring out how much water your lawn and garden really need is easy with the Watering Index and Calculator.  Get started by using the calculator below to create a customized watering schedule.  Then use the Watering Index daily, weekly or monthly to adjust your schedule. The Watering Index is updated daily.  You could save as much as 1,000 gallons a month by watering your plants only as much as they need.

The Watering Calculator is a tool that estimates the correct amount of water to give your landscape or garden every week.  Developed by the city of San Diego, it provides customized watering schedules by zip code based on data from the California Irrigation Management Information System (CIMIS) weather station network.

It has been designed to give you a schedule for the maximum amount of water which your plants or lawn may need each week of the year. For example, in January, your plants may need to be watered for a total of six minutes per week. Come July, they may need 24 minutes per week.

The calculator has been simplified by using average numbers for weather, plants, and soils within zip codes of the urban Southern California area.  These are only suggested run times, so you will need to observe plant health and/or soil moisture levels and make adjustments as necessary.

How to use the Watering Calculator:

  • Answer the questions below for each area of your yard.  You can create a watering schedule for up to 6 areas at one time.
  • When complete, click on the button below to see your customized watering schedule.

Tips for watering during water restrictions:
Due to dry conditions and limited water supplies, some areas are restricting outdoor water use.  These regulations vary across Southern California, and the watering calculator does not create a schedule based on local restrictions.  The following tips will help you schedule landscape watering:

  • Check with your water provider to find out the watering days and times allowed in your area.
  • Enter your landscape information into the watering calculator and create a watering schedule.
  • Divide the total minutes per week in your watering schedule by the number of days per week you may water.  For example, if the calculator shows you should water one area a total of 20 minutes per week and local regulations limit watering to 2 days per week, you will want to water 10 minutes each day.
  • Watch for run-off.  If you water for longer periods, water may run off and be wasted.  Many controllers have a feature that allows for multiple start times so you can “cycle and soak”.  Watering for shorter periods allows the water to soak in.
  • To prevent run-off, multiple start times of shorter duration may be set before and/or after any time restrictions in your area. 


1. What is your zip code? (Only zip codes within urban Southern California are included.)
2. What would you like to call this landscape area? (front yard, citrus trees, etc)
3. What type of plants are you watering?
Look here for examples of Grasses, Ground Covers, Shrubs, or Trees )
4. On this scale from Sandy to Clay, how would you describe your type of soil?
Sandy Loam
Clay Loam
5. What type of watering system do you have?
Sprinkler* Micro-Spray*
Impact Rotor* Bubbler
Gear Rotor* Drip
If you are using a Sprinkler, Rotor, or Micro-Spray, and you know your application rate, please enter it here:

watering calculator

watering index
IMPORTANT: The Watering Calculator does not reflect local mandatory conservation measures that may be in effect because of the current water supply shortage. Please check with your water provider to find out what watering days and times are allowed in your area.