Sprinkler systems might seem simple, but they require intricate planning, precise design and detailed calculations to operate efficiently.
A well-designed irrigation system conserves water by distributing it evenly and effectively and takes into consideration the specific plant materials and micro-climates of your landscape. In contrast, poorly designed systems often lead to excessive water use to make up for their inefficiencies.
Recognizing the crucial role of irrigation design in water conservation, the Texas Commission on Environmental Quality has implemented stringent regulations that govern design, installation and modification of sprinkler systems across Texas. These regulations ensure that both new and modified systems adhere to the highest standards of efficiency and conservation.
Contractors working on these systems must have a state-issued license and undergo thorough training to comply with these regulations effectively. Homeowners who choose to install their systems themselves are allowed to do that but must also adhere to state laws when doing so.
For a detailed understanding of these rules, you can consult TCEQ’s Landscape Irrigator’s Rule Companion. Additionally, note that local municipalities, such as the City of San Antonio, may impose even stricter guidelines than those set by TCEQ. So, checking local codes is also essential to ensure full compliance.
Here are some important topics to consider when designing or modifying your sprinkler system.
Irrigation design
- An effective and efficient irrigation system must account for key factors such as static water pressure and pressure losses in pipes, valves, meters and backflow devices. Understanding these elements is essential for installing a system that meets both manufacturer specifications and state regulations. The design process begins with creating a detailed map of the system, either on paper or digitally, outlining all necessary components and their layout. Calculations are then made to ensure each component functions properly and provides uniform water coverage throughout the landscape.
Backflow device
Water in irrigation systems often becomes stagnant and contaminated, rendering it non-potable and unsafe for drinking. To prevent this water from contaminating residential potable water supplies, state regulations require the installation of adequate backflow prevention devices. In most San Antonio homes, a double-check type backflow assembly is acceptable, typically installed underground at the system’s outset. Some residences, such as ones with septic systems, may require more robust backflow assemblies, like the reduced-pressure principle type, to ensure greater protection.
Pressure compensation
Water in irrigation systems is propelled by pressure, which can be supplied by gravity from a local water tower or a pumping system. Each component, such as sprinkler heads, nozzles and drip tubing, is designed to function within a manufacturer-specified pressure range. Excessive pressure can cause water to atomize into a fine mist, leading to inefficient watering. Insufficient pressure, on the other hand, may prevent sprinkler heads from activating or cause uneven water distribution. A well-designed system accurately measures initial static pressure to ensure each component operates within its optimal range. If your system is experiencing high pressure, pressure-reducing components are available, and SAWS offers rebates on pressure-regulating heads to effectively mitigate these issues.
Head-to-head coverage
- Efficient water delivery in landscaping starts with the correct layout and design of sprinklers. Manufacturers typically recommend head-to-head coverage, ensuring that the spray radius of one sprinkler head overlaps with the next. This approach provides the greatest distribution uniformity, allowing for even water coverage across the area. Placing sprinkler heads too far apart leads to insufficient coverage and dry spots, which often causes the system to run longer than necessary, wasting water even in areas that receive adequate moisture.
Matched precipitation
- Each sprinkler emission component — heads, nozzles, or drip emitters — has a manufacturer-specified precipitation rate that indicates how quickly it waters the landscape. For example, a spray nozzle may deliver 2 inches of water per hour, a standard drip zone 1.44 inches per hour, and a rotor head only 0.5 inches per hour. Thus, a rotor head would take four times as long to deliver the same amount of water as the spray nozzle. For irrigation system efficiency, it’s critical each device within a zone matches these precipitation rates to ensure uniform water distribution. Mixing different types of heads in the same zone can create uneven watering, with some areas being overwatered and others under-watered.
Hydrozoning
- Landscapes vary widely in vegetation types and exposure to environmental elements. For example, drought-tolerant plants at the front of your house require different watering than an adjacent Bermuda grass lawn. Similarly, grass in areas fully exposed to sun will have different needs from areas shaded by trees. A well-designed sprinkler system accommodates these differences by considering both vegetation type and micro-climates. It organizes the irrigation into zones through a method called hydro-zoning, grouping plants with similar water needs and climate exposure. This approach optimizes water usage and efficiency by tailoring watering schedules to the unique needs of each zone.
While these elements are fundamental to good design, there are additional elements, like overspray prevention and moisture sensors, that can further enhance the efficiency of your sprinkler system. Most of these elements are regulated by TCEQ and considered minimum requirements under state law for the installation of a sprinkler system.
If you’re concerned that your sprinkler system isn’t operating as efficiently as possible, consider taking advantage of our free irrigation consultation! A specially trained irrigation specialist will visit your property to evaluate your system with you.
