Using Less Water per Cycle

Once you know your system is leak free, you can start to actually conserve water.  Per irrigation cycle, you can only save water two ways.  You can run for fewer minutes, or you can set your system up to use less water per minute.  It really is that simple.  Let’s look at the controller settings first.  What is your run time per station?  Are they all the same?  Are you using cycle and soak? 

Controllers are set to a default when they are installed.  I hope that yours has been changed.  I’m not going to tell you how long to set them, only someone onsite can determine that.  Irrigation audits are a great way to determine the necessary run time.  Barring an audit, you will have to use the precip rate in the nozzle literature.  I will mention a couple of key points though.  Make sure that you are using cycle and soak.  I like to have soak times of 40-60 minutes, and we only run each cycle around 8 minutes for rotors, and 2 minutes for sprays.  Any more than that and we begin to see run off.  If you see run off, you’ve gone too far.  Turn your run times down.  Each area of your property will need a slightly different time.  Hills and soil type will be large factors here. 

Remember, dry landscapes and turf are good things.  It encourages root growth and will force the roots deeper to create a larger root zone profile.   You can save a large amount of water simply by turning your system down a minute or two.  Rarely does it make a difference in quality.  If you had every station set to 10 minutes, and you cut 1 minute out, you save 10% right off the top.  This is a real savings, not theoretical.  Try it; we were able to turn our times down 20% by using cycle and soak, and a further 10% by just running less time.  That is a lot of water. 

Using less water per minute is where technology comes into play.  What heads and nozzles are on the property?  How old are they?  Are newer styles available to save water?  Saving water through parts is more about distribution uniformity than anything else.  If you apply water more uniformly, you have less dry spots and can cut your run times down.  Some parts will save water directly though.  For example, using pressure regulated heads will help save a lot of water in an over pressurized system.  Use a pitot gauge and check your pressure at the nozzle.  If it is above the recommended psi, look at regulated heads or valves.  Most manufacturers have these heads and adapters that can be screwed into the solenoid port.  Rainbird claims that their regulated 5004 series can save a gallon of water per head per minute.  In our experience, that number is close.  So let’s say you have a zone with 5 heads with 3 gpm nozzles.  That is 15 gallons per minute, but in an over pressurized system, you may be using 18 or 20.  This extra pressure is out of spec with the nozzle design and is not applied uniformly.  While dropping the pressure does not make for a good visual effect, irrigation audits will confirm that it is being applied uniformly.  Also look for heads that have seals that hold back head pressure when the system is off.  Factoring in pipe size and cycles per night, we had zones that were wasting 200 gallons of water every time they ran.  Again, that adds up quickly. 

Pick your nozzles carefully, as spray heads are notoriously inefficient.  I prefer Rainbird HE-Van nozzles where I must have a spray head, and Hunter MPRotator where they make sense.  More on that later. 

Next up is reducing the number of cycles.