Effective water management means to provide controlled amounts of irrigation water based on seasonal plant material needs and available resources. Good water management can only be achieved by a thoughtful design. Examples of questionable design include walkways and roadways that have never really required much daily irrigation, but are often included in rotor and spray zones irrigate to a far corner. Shrub material can be very happy with half the amount of water as an annual bed. How many annual beds are tied into shrub zones, and who is going to let an annual bed suffer from lack of water?

Municipalities often attempt to discourage overspray of impervious areas with reams of zoning requirements, but few inspectors actually can interpret an irrigation plan. Fewer still actually understand how a system is going to work (nor can many landscape architects, I’m sorry to say). Commercial maintenance companies can be more reactionary than proactive, which is to say they may get out to fix a blown head right away, but rarely if ever make seasonal adjustments to the time clock.

According to Water Right by Dr. H. Marc Cathey, one inch of water is generally recommended for maintaining a viable landscape including turf, trees and flowers.

What all this boils down to is quite simple: Most irrigation systems put out much more water than plants really need. There are a few things an irrigation designer or installer can keep in mind when putting a system together that can dramatically decrease water consumption. Perhaps the most obvious but often overlooked is a rain shut-off device. Most devices will work on any irrigation system by temporarily “switching off” the common wire. Nothing in the world of irrigation is more wasteful than an irrigation system operating full blast during or just after a rain storm, yet I often see this happening in my area. Another very common and easily avoidable waste of water happens when the designer or installer tries to save money by using rotors over sidewalks and patios. An irrigation system will take slightly more time and materials to install spray heads to avoid over spray of paved areas, but the contractor should not view this extra work as a money saving option. Explain how much water your client could be wasting, and charge a fair price for a good job. Almost all clients will agree to a slightly higher cost for a better job when wasted water is put into perspective. The following chart may help:

My opinion on this is that the client is paying good money for an efficient system, even though the client may not understand what an efficient system is. As an irrigation designer, I owe it to my clients to get as much water onto the plants, and out of the gutter as I can.

Another big hit to the water bill comes when you irrigate shrub material with sod areas, or shrub material with annual beds. The concept is really very simple when you look at it: X number of square feet of sod will require Y gallons of water per week. The same can be said for each plant type in the landscape, but not all plant types need the same amount of water. A properly designed irrigation system should respect this. Viburnum and Liriope need much less water than St. Augustine sod. This next chart is a simple breakdown of water use at a small residence:

One way to decrease the costs on an average water bill is to irrigate shrub material with sod areas, or shrub material with annual beds. The concept is really very simple when you look at it: X number of square feet of sod will require Y gallons of water per week. The same can be said for each plant type in the landscape, but not all plant types need the same amount of water. A properly designed irrigation system should respect this. For example, Viburnum and Liriope need much less water than St. Augustine sod. Choosing the appropriate plant materials will ultimately effect the success of the project and the amount of water saved.

Local conditions throughout the country require varying amounts of water, use these numbers for comparison only. When shrubs are on the same zone as your annual beds, that zone will need to apply 1.5" per week minimum (in Central Florida) to keep the annuals happy. The shrub zones only need .75" of water. Therefore, you are over watering your shrubs by .75" per week. By using the Water Consumption chart on previous page, the following assumptions may be made:

• Shrubs and Turf on same zone - 1" per week

37.4 wasted gallons per week

• Shrubs and Annuals on same zone - 1.5" per week

112.2 wasted gallons per week

• Turf and Annuals on same zone - 1.5" per week

1,558.5 wasted gallons per week

This may not sound significant in a single residence, but my projects tend to cover several acres of mixed irrigated area, and these numbers take on new importance when you increase the above quantities by many thousands of square feet.

Another way to manage water is to pay attention to the time of year, and adjust the time clock accordingly. Some months it will rain, and some months it will be dry. This is always the case. The system must be flexible enough to handle the driest months and must be able to decrease water when there is plenty of rain. As a designer, I can provide for easy seasonal adjustments to the time clock station run times, but I must rely on the maintenance company or resident to make the adjustment. The best I can hope to do is to educate the end user of the system on how to make those adjustments, which I do through irrigation education seminars at a local botanical garden. These seminars take up a relatively small amount of time and can have big rewards, especially in the residential market where people will begin to recognize your name.

Low volume irrigation use is being encouraged by many municipalities as a way of saving water, but restricting irrigation volume is not the answer to conserving water on larger projects. Accurate, efficient placement of heads, providing plant specific irrigation, and seasonal adjustments to water schedule will go farther to save water than reducing the capacity of the system. If your client is willing to pay a little more for a superior system, drip irrigation and root zone emitter systems are the most efficient, and can be used for shrub and annual/perennial zones. These zones can also be run during the daytime without affecting the use of the site - unlike rotor or spray zones.

A few more tips on water management that are unrelated to design of the system, but directly related to how much water the plants require include fertilization, plant maintenance, system maintenance, and the start time of the system.

1) Plant material water use is definitely affected by fertilizer application schedules and plant maintenance schedules. When fertilizers are applied to plant material they tend to put on extra growth, which requires additional irrigation water as the water becomes the limiting factor in the plants growth. Major pruning can also produce a growth spurt in plant material, which requires additional water resources. Timing fertilizer applications and maintenance during typically rainy times of the year will reduce the amount of supplemental irrigation required.

2) Fix the broken heads. Don’t put it off unless your trying to clean the curb gutters and surrounding cars. Not only does a broken head obviously waste water, but also can damage the surrounding landscape by washing out the soil surrounding the break. Regular weekly, or bi-weekly inspections can head off a much larger problem by catching a break early. There are irrigation products available that will limit the amount of water lost during a break, which could be incorporated into the design, and could help reduce washout from broken heads or pipes.

3) Watering schedules can affect fungus/disease growth in the landscape. Many diseases and fungi require about six hours of moisture to proliferate. By timing your system to irrigate as late in the morning as possible you may restrict their growth, as a result use less chemicals in the landscape, reduce stress on the plants, and ultimately reduce water consumption. If your area is very windy, try to irrigate in the very early morning hours when the wind is usually calmer. This will save water from overspray by the wind, and the wind will tend to dry out the plants sooner, which limits fungus/disease growth.

A properly designed irrigation system promotes plant health while conserving water.

The bottom line is that irrigation systems are expensive to operate and wasting water serves no purpose. An efficient design will reduce the annual operating cost over many years, and will help to build your reputation as a quality irrigation contractor.