1. (a) This section applies to landscaped areas requiring permanent irrigation, not areas that require temporary irrigation solely for the plant establishment period. For the efficient use of water, an irrigation system shall meet all the requirements listed in this section and the manufacturers' recommendations. The irrigation system and its related components shall be planned and designed to allow for proper installation, management, and maintenance. An irrigation design plan meeting the following design criteria shall be submitted as part of the Landscape Documentation Package.

2. (b) Irrigation System Efficiency.

   1. (1) The irrigation system must be designed and installed to meet, at a minimum, the irrigation efficiency criteria as described in Section 493.3 regarding the Maximum Applied Water Allowance.

   2. (2) For the purpose of determining Estimated Total Water Use, average irrigation system efficiency is assumed to be:

      1. (A) 0.75 for overhead irrigation systems; and
      2. (B) 0.81 for drip irrigation systems.
   3. (3) Sprinkler head spacing shall be designed to achieve the highest possible distribution uniformity using the manufacturer's recommendations. Head-to-head coverage is recommended.

3. (c) The irrigation design plan, at a minimum, shall contain the following:

   1. (1) location and size of separate water meters and submeters;
   2. (2) location, type, and size of all components of the irrigation system, including controllers, main and lateral lines, valves, emission devices, moisture sensing devices, rain sensors, quick couplers, pressure regulating devices, and backflow prevention devices;
   3. (3) static water pressure at the point of connection to the public water supply;
   4. (4) flow rate (gallons per minute), application rate (inches per hour), and design operating pressure (pressure per square inch) for the emission devices controlled by each station;
   5. (5) identification of special landscape areas irrigated with and water features using recycled water as specified in Section 490.1(a)(3);
   6. (6) identification of any applicable graywater discharge piping, system components, and landscape areas where graywater is distributed;

   7. (7) Identification of hydrozone areas shall be designated by number, letter, or other designation as identified on the landscape design plan. Designate the areas irrigated by each valve and assign a number to each valve using the Water Efficient Landscape Worksheet (see Appendix A). This table can also assist with the irrigation audit and programming the controller.

      1. (A) Each valve shall irrigate a hydrozone, or part of a hydrozone, with similar site, slope, sun exposure, soil conditions, and plant materials with similar water use.
   8. (8) the following statement: “I have complied with the performance compliance option criteria of the MWELO and applied them accordingly for the efficient use of water in the irrigation design plan.”; and
   9. (9) the signature of the designer of record. (See Division 3, Chapter 3.5, Article 3 of the Business and Professions Code).

4. (d) General Design Criteria.

   1. (1) Backflow prevention devices shall be required to protect the water supply from contamination by the irrigation system as specified in the California Plumbing Code (Cal. Code Regs., Title 24, Part 5, Chapter 6). A project applicant shall refer to the applicable local agency code (i.e., public health) for additional backflow prevention requirements.
   2. (2) The design of the irrigation system shall conform to the hydrozones of the landscape design plan.
   3. (3) Emission devices shall be selected based on what is appropriate for the plant type within that hydrozone.
   4. (4) Where feasible, trees shall be placed on separate stations from hydrozones that include shrubs, groundcovers, and turfgrass to facilitate the appropriate irrigation of trees. The mature size and extent of the root zone shall be considered when designing irrigation for the tree.
   5. (5) In mulched planting areas, the use of low-pressure and low volume irrigation systems is required to maximize water infiltration into the root zone.
   6. (6) Areas less than 10 feet in width in any direction shall be irrigated with subsurface irrigation or other means that produces no water waste, runoff, or overspray.

   7. (7) Individual hydrozones that use a mix plants of with low and moderate plant factors, or moderate and high plant factors, may be allowed if the plant factor used in the calculation of the estimated water use (EWU) is either:

      1. (A) plant factor calculation is based on the proportions of the respective plant factors; or
      2. (B) the highest plant factor is used.
   8. (8) Individual hydrozones that use a mix of plants with high and low plant factors shall not be permitted.
   9. (9) Relevant information from the soil management plan, such as soil type and infiltration rate, shall be utilized when designing irrigation systems.

   10. (10) Overhead irrigation shall not be permitted within 24 inches of any non-pervious surface. Allowable irrigation within the setback from non-permeable surfaces may include drip irrigation, or other low flow non-spray technology. The setback area may be planted or unplanted. The surfacing of the setback may be mulch, gravel, or other porous material. These restrictions may be modified if:

       1. (A) no runoff occurs; or
       2. (B) the adjacent non-pervious surfaces are designed and constructed to drain entirely to landscaping; or
       3. (C) the irrigation designer specifies an alternative design or technology, as part of the Landscape Documentation Package, and clearly demonstrates strict adherence to the prevention of water waste. Prevention of overspray and runoff must be confirmed during the irrigation audit.

   11. (11) Restrictions regarding overspray and runoff in any irrigation system may be modified if:

       1. (A) the landscape area is adjacent to pervious surfacing and no runoff occurs; or
       2. (B) the adjacent non-pervious surfaces are designed and constructed to drain entirely to landscaping; or

   12. (12) Slopes greater than 25% shall not be irrigated with an irrigation system using an application rate exceeding 0.75 inches per hour.

       1. (A) This restriction may be modified if the landscape designer specifies an alternative design or technology, as part of the Landscape Documentation Package, and clearly demonstrates no runoff or erosion will occur. Prevention of runoff and erosion must be confirmed during the irrigation audit.
   13. (13) It is highly recommended that the project applicant or local agency inquire with the local water purveyor about peak water operating demands (on the water supply system) or water restrictions that may impact the effectiveness of the irrigation system.

5. (e) Irrigation System Components.

   1. (1) Meters.

      1. (A) Pursuant to California Water Code section 535, a water purveyor with 15 or more service connections shall install a dedicated irrigation meter(s) for new retail water service to a property with more than 5,000 sq. ft. of irrigated landscape excluding single-family residential connections and connections for the commercial production of agricultural crops or livestock.

      2. (B) For the purposes of this model ordinance, a submeter or dedicated irrigation meter shall be installed and may be used to assist with leak detection and water management for:

         1. 1. non-residential landscapes with an irrigated landscape of 1,000 sq. ft. but not more than 5,000 sq. ft.
         2. 2. residential landscapes with an irrigated landscape of 5,000 sq. ft. or more.

   2. (2) Water Pressure.

      1. (A) Static water pressure, dynamic or operating pressure, and flow reading of the water supply shall be measured at the point of connection. These pressure and flow measurements shall be conducted at the design stage. If the measurements are not available at the design stage, the measurements shall be conducted at installation.
      2. (B) If the static pressure is above or below the required dynamic pressure of the irrigation system, pressure-regulating devices such as inline pressure regulators, booster pumps, or other devices shall be installed to meet the required dynamic pressure of the irrigation system.
      3. (C) If the water pressure is below or exceeds the recommended pressure range of the specified emission devices, the installation of a pressure-regulating device is required to ensure that the dynamic pressure at each emission device is within the manufacturer's recommended pressure range for optimal performance.

   3. (3) Water Waste Prevention Equipment.

      1. (A) The irrigation system shall be designed to prevent water waste.
      2. (B) Master shut-off valves are required on all projects except landscapes that make use of technologies that allow for the individual control of sprinklers that are individually pressurized in a system equipped with low pressure shut down features.
      3. (C) Manual shut-off valves (such as a gate valve, ball valve, or butterfly valve) shall be required, as close as possible to the point of connection of the water supply, to minimize water loss in case of an emergency (such as a break in the pressurized pipeline that delivers water from the water source to the valve or outlet) or routine repair.
      4. (D) Check valves or anti-drain valves are required on all sprinkler heads where low point drainage could occur.
      5. (E) Swing joints or other riser-protection components are required on all risers subject to damage that are adjacent to hardscapes or in high traffic areas of turfgrass.
      6. (F) Flow sensors that detect high flow conditions created by system damage or malfunction are required for all on non-residential landscapes and residential landscapes of 5000 sq. ft. or larger.

   4. (4) Emission Devices.

      1. (A) Emission devices shall have matched precipitation rates, unless otherwise directed by the manufacturer's recommendations.

      2. (B) All irrigation emission devices must meet the requirements set in the American National Standards Institute (ANSI) standard, American Society of Agricultural and Biological Engineers'/International Code Council's (ASABE/ICC) 802-2020 “Landscape Irrigation Sprinkler and Emitter Standard,” which is herein incorporated by reference.

         1. 1. All overhead irrigation systems installed in the landscape must document a low quarter distribution uniformity of 0.65 or higher using the protocol defined in ASABE/ICC 802-2020.
      3. (C) Non-rotating spray sprinkler bodies are required to meet standards described in California Code of Regulations, Title 20, Division 2, Chapter 4, Section 1605.3(x).

   5. (5) System Controls.

      1. (A) Automatic irrigation controllers utilizing either evapotranspiration or soil moisture sensor data utilizing non-volatile memory shall be required for scheduling irrigation events.
      2. (B) Sensors (rain, freeze, wind, etc.), either integral or auxiliary, that suspend or alter irrigation operation during unfavorable weather conditions shall be required on all irrigation systems, as appropriate for local climatic conditions. Irrigation should be avoided during windy or freezing weather or during rain.

Note: Authority cited: Sections 65596 and 65596.5, Government Code. Reference: Sections 65593, 65596 and 65596.5, Government Code.

History

1. New section filed 1-2-2025; operative 1-2-2025 pursuant to Government Code section 11343.4(b)(3) (Register 2025, No. 1).