Automatic sprinkler systems are convenient, but they can easily waste 30%¹ of the water used for irrigation. Setting proper schedules and keeping up with your annual maintenance are the best ways ensure that your system is working effectively and efficiently.
Set A Base Schedule
The first step to fine tuning your sprinkler system is to determine its output or how long it takes to water 1 inch of water². See how to measure your sprinkler's water use.
Next, you can set your sprinkler to water a base schedule³, or the amount it needs in the hottest, driest part of summer (100% of its maximum water need). This feature should be programmed into most automatic sprinkler systems.
- Determine if it is equipped with a "water budget" or “percent adjust” feature (this should be in the controller box).
- Set the "water budget" or “percent adjust” to 100%.
Once you set your controller’s base schedule, you will be able to adjust it to reflect your landscape’s needs and local weather conditions by using the Weekly Watering Number.
Adjust Your Watering Schedule
The key to efficient irrigation is to adjust watering schedules frequently during the season. If you set your automatic controller once and let it run all season, you’re wasting a lot of water that could be damaging your plants and your pocketbook.
Most modern controllers allow you to easily set your base schedule and then adjust your weekly watering schedule based on the weather. You can make these weekly adjustments by using these simple steps:
- Set the base schedule for each watering zone at 100%.
- Adjust your "water budget" or “percent adjust” feature for each watering zone to the percentage that corresponds with the Weekly Watering Number 4.
For example, if the Weekly Watering Number is 1.27 inches you will adjust the percentage to 130% and the timer will increase times for all zones. Similarly, if the Weekly Watering Number is .72 inches you will adjust the percentage to 75% and the timer will decrease times for all zones5.
1 Source: Irrigation Association
2 Ideally your system was designed with different watering zones, or areas that contain plants with similar water needs. If this is the case, you will need to determine the rate that each zone puts down an inch of water output with plant materials that can be programmed to water different plant types.
3 If you water with a hose or your sprinkler system does not allow that kind of adjustment, then you can use the Weekly Watering Number as a guideline for manually adjusting your watering duration or frequency.
4 Keep in mind that the Weekly Watering Number is a general reference and the actual water requirements for any given area should take into account the amount of sun or shade an area receives, the slope of the site, the soil conditions and the type of plant material being watered. All of these factors should be taken into account when setting the base watering schedule.
5 Some controllers will allow you to adjust to the nearest 1% while others only allow you to adjust in increments of 10%, so you may have to round up or down.