The following article list most of the problems with lawn and landscape sprinkler systems that cause excessive use of water or water that is being wasted. Use this article to evaluate your irrigation system and make improvements to improve the efficiency of your system.
System Pressure: Improper pressure at the sprinkler is a big waste of water, sprinklers are designed to operate at a specific pressure the closer your sprinkler is operating at that pressure the better the uniformity of application. What is uniformity of application you ask? That is a great question and I will define uniformity of application as it relates to sprinkler system now because it is one of the key factors in saving water.
Let’s take a look at two illustrations
As you can see in the top illustration the water penetrates the soil in an even pattern to the full depth of the root. Any water that goes deeper than the roots is wasted water and any area that does not penetrate to the full depth of the roots may cause brown spots in the turf or stressed plants in the landscape. So the basis of a uniform application is to apply the irrigation water evenly to the surface being irrigated.
The following are more methods of improving uniformity.
Spacing of sprinklers: Sprinklers should always be positioned so that water from one sprinkler reaches the adjacent sprinkler; this is known as head to head coverage as shown below.
Courtesy of www.irrigationtutorials.com
If your sprinklers do not have head to head coverage you will end up having an area of deficit in the middle of the sprinkler coverage. It is alright to spray over or past an adjacent sprinkler head but having less than head to head coverage will be detrimental and over watering to compensate for this will occur causing more wasted water.
Mixed precipitation rate sprinklers on the same zone: This is a common problem with residential sprinkler system. If you have different type of sprinklers on the same zone or valve you most likely have unmatched precipitation rates. If you have spray sprinklers and rotary sprinklers on the same zone that is an indication you have this problem. You might also have this problem with your rotary sprinklers if they were not nozzled correctly. The nozzling of rotary sprinklers is based on the area of coverage. If a half circle sprinkler is flowing at 2gpm than a full circle sprinkler should be flowing twice as much because it is covering twice the area. So full circle would be 4gpm and quarter circle would be nozzled with a one gpm nozzle.
Improper scheduling: Scheduling of your sprinklers run time determines how much water is applied, how often and at what rate. You can adjust the amount of water applied by increasing or decreasing the length of time your sprinklers operate. How often should you make adjustments to your systems schedule? Most people only adjust their system when they feel the landscape is not receiving enough water, turning it down happens less often. Ideally a monthly schedule adjustment would be great. New weather based irrigation controllers will automatically adjust the run times on a daily basses giving you the greatest water savings. When scheduling how long a cycle should run for any one zone the key is to make sure runoff does not occur during the cycle. If a zone needs to run for 40 minutes it would be best to break it up into two 20 minute cycles with a rest of at least 30 minutes between cycles, this is referred to as cycle and soak in the irrigation trade and it helps to eliminate run off which is wasted water.
Not using rain sensors or moisture sensors: Every sprinkler system should have an operational Rain Sensor. These devices will turn off the system once an adequate amount of rain has fallen and will suspend watering for several days.
Soil moisture sensors determine the level of moisture in the soil at the root zone of the plants and controls how much water is applied to provide the optimum growing conditions for the plants. When using soil moisture sensors, several sensors will need to be placed around the landscape to measure the different hydrozones. A hydrozone is defined by plant water requirements, soil conditions and climatic factors.