Water Efficient Irrigation

From April 1st – October 31st, spray irrigation is limited to once a day up to twice a week, on any day(s) you choose. Running spray irrigation once a week and hand watering elsewhere as needed is usually sufficient.

Spray irrigation controllers should not be set to run after 10 AM or before 6 PM, recommended 3-7 minutes for run times per zone. Spray irrigation CANNOT run during rain, and doing so violates the City of Princeton’s Water Conservation Plan which may result in a fine. Spray irrigation CANNOT be evident in water waste (including excessive draining into nearby storm drains, sidewalks, streets, or other impervious surfaces), and doing so violates the City of Princeton’s Water Conservation Plan which may result in a fine.

We recommend using a rain sensor and downloading MyWaterAdvisor2 to track your usage to help prevent fees.

Please scroll down to read more about the importance of water and water conservation.

Water is the most important resource to sustain life and as the Earth's population grows, the need for water grows. Water is being used and wasted faster than it can be replenished.

How Much Water Does Your Irrigation System Use

Try these calculations for your yard! First, determine what kind of sprinkler head you have:

  • Spray Head - Up to 3 gallons per minute (per head)
  • Rotor Head - Up to 9 gallons per minute (per head)

Then, plug in the numbers below:

  • The number of sprinkler heads multiplied by the number of gallons per minute multiplied by the number of minutes scheduled per use equals the number of gallons emitted per use.

For example: 

Water Efficient Calculator Graphic (PNG)

The average spray irrigation head pushes out 3 gallons of water per minute. The average property has 8 irrigation heads in total. Compare the water usage for the average home with spray irrigation below:

Spray Irrigation Graphic (PNG)

Using the same average stats with a rotor head irrigation system, which pushes out 9 gallons per minute, compare the water usage below:

Rotor Irrigation Graphic (PNG)

If your lawn is newly placed either through seed or sod, water for longer periods - up to twice a week per City ordinances. If your lawn is established past the point of 4 weeks, it is recommended to slowly reduce your water usage to once a week, and if it rains more than an inch and a half for the week, to not water at all.

WaterMyYard can help you determine if you need to water in accordance with the local weather. Allowing the soil to dry at a depth of several inches will help the grass develop deep roots.

Think about what your spray/rotor irrigation is hitting.

Watering impervious surfaces (areas that cannot take in water, including but not limited to roadsides, sidewalks, and fences) is strictly against City ordinances and may result in a fine. Watering the foliage of trees/flowers can cause them to wilt, rot, or become prone to diseases. Watering when the sun is highest, or between 10 AM and 6 PM, can "sunburn" your plants and yard. Think about your own skin:  you wouldn't sit out in the hot sun with wet skin and not expect to experience a hot sensation or burn. Your plants are the same way. Be mindful of the wind. Wind can change the direction of your irrigation pattern and reduce the amount of water hitting your yard. During times of high wind, when watering your yard can't wait, it is best to wait for the evening hours or early morning hours and water by hand.

Drip Irrigation

Do you have drip irrigation? Drip irrigation uses up to 1.5 gallons per minute in each 10x10-foot area. Plug in the numbers to the formula given if you have drip irrigation:

  • The number of square feet of irrigated lawn equals the number of gallons emitted per use multiplied by the number of minutes scheduled per use.

Drip Irrigation Graphic (PNG)

Any variance above your normal household consumption could indicate any of the following:

  • Broken or damaged sprinkler heads
  • Check for multiple timer programs (A, B, and C)
  • Check weekly and daily timers
  • Incorrect irrigation timer settings
  • Leaky or running toilet (Public Works has free tablets to help you check your toilet for leaks)
  • A power surge could reset a timer to factory defaults, causing it to run more frequently than expected

Irrigation Efficiency

  • Lawn irrigation can be 40 to 60% of your water bill
  • Watering less than two times a week is usually sufficient
  • Brown grass does not mean dead grass
  • Frequent watering promotes shallow roots instead of deep long-lasting roots

For more information on how much you should water your lawn based on the weather visit Water My Yard online.

What Can You Do?

  • Option 1: Set your controller properly to water your yard and adjust it with the seasons.
    • Check your current controller settings! The controller for your sprinkler system is in your garage on the wall.
    • Be sure it is set to the correct date and time
    • Program A is usually sufficient. Program B and program C can be switched to “OFF”. These two programs are for the same zones, they will just set the zones off a second time at a different time.
    • Choose your start time for each zone. Between 3 AM – 6 AM is best. If programs B & C are both off, be sure they have no start times. Why between 3 AM – 6 AM?
      • Less water loss from evaporation
      • Least chance of attracting mosquitoes
      • Least chance of developing root rot
  • Set your time for each zone within your programs.
    • 💧 means it will run.
    • 🚫 means it will not run.
    • Between 3 – 7, minutes is usually sufficient. We suggest 3 minutes for the lawn and 4 minutes for the trees. If you have a soaker hose, refer to your manufacturer’s recommendations for a run-time.
    • Choose the days your system will run.  We suggest either once a week, like Wednesday, or twice a week, Monday, and Thursday. That way you have 2-3 days between each watering.
    • Twice a week is all that’s permitted between April 1st – October 31st. A maximum of once a week is permitted from November 1st – March 31st. Every 15-20 days is usually adequate during the winter.
  • Option 2: Shut your water off!
    • Manually turning your sprinklers on or hand watering gives you complete and total control of your landscape, lawn, and garden.
    • Allowing your plants to stress a little can be helpful in acclimating them to the weather and soil as it promotes deep root growth and ultimately reduces water run-off.
    • Saves the most water, meaning you spend less!


  • Plant native and drought-resistant plants that require less watering
  • Taller grass holds water more efficiently, don't cut more than one-third of the grasses length at one time
  • Buy or make a rain bucket to water your plants, AgriLife Extension has resources on the roof-water collection and rain barrels here. 

For more information on native plants visit Texas SmartScape online.

Water & Irrigation Regulations

April 1 through October 31

  • Water no more than twice per week
  • Less than twice per week is usually adequate
  • Watering is prohibited from 10 am to 6 pm.
  • Additional Landscape watering may be provided by a hand-held hose with a shutoff nozzle, dedicated irrigation drip zones, and/or soaker hose provided no runoff occurs.

November 1 through March 31

  • Limit landscape watering to one day per week
  • Every 15 to 20 days is usually adequate


  • Irrigation systems that water-impervious surfaces (sidewalks, roads)
  • Outdoor watering during precipitation or freeze events
  • Poorly maintained sprinkler systems that are actively wasting water
  • Excess water runoff or other obvious waste
  • Overseeding, sodding, sprinkling, broadcasting, or plugging with cool-season grasses or watering cool-season grasses, except for golf courses and athletic fields.
  • Use of potable water to fill or refill residential, amenity, and any other natural manmade ponds


  • Non-commercial car washing must be done when using a hose with an automatic shut-off nozzle.
  • New irrigation systems require freeze sensors and/or ET or Smart Controllers, which must be maintained
  • Irrigation systems must be inspected at the same time as the initial backflow preventer inspection
  • New irrigation systems must be in compliance with state design and installation regulations.