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Chapter 15 — ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS

1504.2 Required Area of Subsurface Irrigation

California Plumbing Code (Title 24, Part 5) · 2019 edition · updated 2026-09-10 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

Fields, Subsoil Irrigation Fields, and Mulch Basins. The minimum effective irrigation area of subsurface irrigation fields, subsoil irrigation fields, and mulch basins shall be determined by Table 1504.2 for the type of soil found in the excavation, based upon a calculation of estimated gray water discharge under Section 1503.8. For a subsoil irrigation field, the area shall be equal to the aggregate length of the perforated pipe sections within the valved zone multiplied by the width of the proposed subsoil irrigation field.

316 2019 CALIFORNIA PLUMBING CODE

any other purpose or distributed to any other persons or part ies. ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS

TABLE 1504.2 DESIGN OF SIX TYPICAL SOILS

[BSC-CG] Irrigation design shall be verified in accor- dance with the California Green Building Standards Code (CALGreen), Chapter 5, Division 5.3.

[HCD 1] Irrigation design shall be verified in accor- dance with the California Green Building Standards Code (CALGreen), Chapter 4, Division 4.3.

TABLE 1504.5 SUBSURFACE IRRIGATION DESIGN

CRITERIA FOR SIX TYPICAL SOILS

TYPE OF SOIL MINIMUM SQUARE
FEET OF IRRIGA-
TION/LEACHING AREA
PER 100
GALLONS OF
ESTIMATED GRAY
WATER DISCHARGE
PER DAY		 MAXIMUM
ABSORPTION CAPAC-
ITY IN GALLONS PER
SQUARE FOOT OF
IRRIGATION/
LEACHING AREA FOR
A 24-HOUR PERIOD
Coarse sand or
gravel
 20
 5.0
Fine sand
 25
 4.0

Sandy loam
 40
 2.5

Sandy clay
 60
 1.7

Clay with consider-
able sand or gravel
 90 1.1


Clay with small
amounts of sand or
gravel
120
0.8

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▸Contents — California Plumbing Code (Title 24, Part 5)
California Plumbing Code (Title 24, Part 5)
  1. Chapter 1 — GENERAL CODE PROVISIONS
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GENERAL REGULATIONS
  4. Chapter 4 — PLUMBING FIXTURES AND FIXTURE FITTINGS
  5. Chapter 5 — WATER HEATERS
  6. Chapter 6 — WATER SUPPLY AND DISTRIBUTION
  7. Chapter 7 — SANITARY DRAINAGE
  8. Chapter 8 — INDIRECT WASTES
  9. Chapter 9 — VENTS
  10. Chapter 10 — TRAPS AND INTERCEPTORS
  11. Chapter 11 — STORM DRAINAGE
  12. Chapter 12 — FUEL GAS PIPING
  13. Chapter 13 — HEALTH CARE FACILITIES AND MEDICAL GAS AND MEDICA…
  14. Chapter 14 — FIRESTOP PROTECTION
  15. ▸Chapter 15 — ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS
    Overview
    1. 1501.0 General.1501.1 Applicability [BSC-CG, DWR & HCD 1]. The
    2. 1501.2 System Design. Alternate water source systems
    3. 1501.3 Permit [BSC-CG, HCD 1, DWR]. It shall be unlawful for a…
    4. 1501.4 Component Identification. System components
    5. 1501.5 Maintenance and Inspection 1, DWR]. Alternate water sou…
    6. 1501.6 Operation and Maintenance Manual [BSC-
    7. 1501.7 Minimum Water Quality Requirements [BSC-
    8. 1501.8 Material Compatibility. Alternate water source systems …
    9. 1501.9 Signage [BSC-CG, HCD 1, HCD 2, HCD 1-AC, &DWR]. Signage…
    10. 1501.10 System Controls. Controls for pumps, valves, and
    11. 1501.11 Hose Bibbs for Single-Family Dwellings [HCD1]. Hose bi…
    12. 1502.2 Supply System Inspection and Test. Alternate
    13. 1502.3 Cross-Connection Inspection and Testing. An
    14. 1502.6 Sizing. Unless otherwise provided for in this chapter, …
    15. 1503.1 General. The provisions of this section shall apply
    16. 1502.4 Separation Requirements. Underground alternate
    17. 1502.5 Abandonment. Alternate water source systems that
    18. 1503.2 System Requirements. Gray water shall be permitted to b…
    19. 1503.3 Connections to Potable and Reclaimed(Recycled) Water Sy…
    20. 1503.4 Location. No gray water system or part thereof shall
    21. 1503.5 Plot Plan Submission. No permit for a gray water
    22. 1503.6 Prohibited Location. Where there is insufficient
    23. 1503.7 Drawings and Specifications. The Authority
    24. 1503.9 Gray Water System Components. Gray water
    25. 1504.2 Required Area of Subsurface Irrigation
    26. 1504.3 Determination of Maximum Absorption Capac-
    27. 1504.4 Groundwater Level. No excavation for an irrigation fiel…
    28. 1504.5 Irrigation, Disposal Field and Mulch Basin Con-structio…
    29. 1504.6 Reserved.
    30. 1504.7 Reserved.
    31. 1504.8 Gray Water System Color and Marking Infor-mation. Press…
    32. 1504.9 Other Collection and Distribution Systems. Other collec…
    33. 1504.10 Testing. Building drains and vents for gray water
    34. 1504.11 Maintenance. Gray water systems and components shall b…
    35. 1505.0 Recycled Water 1505.1 General. The provisions of Supply…
    36. 1505.3 System Changes. No changes or connections shall
    37. 1505.4 Connections to Potable or Reclaimed (Recy-cled) Water S…
    38. 1505.2 Permit. It shall be unlawful for a person to construct,
    39. 1505.5 Initial Cross-Connection Test. A cross-connection test …
    40. 1505.6 Recycled Water Recycled water supply system materials s…
    41. 1505.8 Valves. Valves, except fixture supply control valves,
    42. 1505.9 Hose Bibbs. Hose bibbs shall not be allowed on
    43. 1505.10 Required Appurtenances. The recycled water
    44. 1505.11 Pipe Separation in Trenches. Reclaimed (recycled) wate…
    45. 1505.12 Signage. Signs in rooms and water closet tanks in
    46. 1505.13 Inspection and Testing. Recycled water supply
    47. 1505.15 Maintenance and Inspection. Recycled water
    48. 1506.0 On-Site Treated Nonpotable Gray Water Sys-
    49. 1506.2 Plumbing Plan Submission. No permit for an
    50. 1506.3 System Changes. No changes or connections shall
    51. 1506.4 Connections to Potable or Reclaimed (Recy-
    52. 1506.5 Initial Cross-Connection Test. A cross-connection test …
    53. 1506.6 On-Site Treated Nonpotable tem Materials. On-site treat…
    54. 1506.7 On-Site Treated Nonpotable Devices and Systems. Devices…
    55. 1506.9 Design and Installation. The design and installation of…
    56. 1506.10 Valves. Valves, except fixture supply control
    57. 1506.11 Signs. Signs in buildings using on-site treated nonpot…
    58. 1506.12 Inspection and Testing. On-site treated nonpotable gra…
  16. Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS
  17. Chapter 17 — REFERENCED STANDARDS
  18. Appendix A — RECOMMENDED RULES FOR SIZING THE WATER SUPPLY SYS…
  19. Appendix B — EXPLANATORY NOTES ON COMBINATION WASTE AND VENT S…
  20. Appendix C — ALTERNATE PLUMBING SYSTEMS
  21. Appendix D — SIZING STORM WATER DRAINAGE SYSTEMS
  22. Appendix E — MANUFACTURED/MOBILE HOME PARKS AND RECREATIONAL V…
  23. Appendix F — FIREFIGHTER BREATHING AIR REPLENISHMENT SYSTEMS
  24. Appendix G — SIZING OF VENTING SYSTEMS
  25. Appendix H — PRIVATE SEWAGE DISPOSAL SYSTEMS
  26. Appendix I — INSTALLATION STANDARD FOR PEX TUBING SYSTEMS FOR …
  27. Appendix J — COMBINATION OF INDOOR AND OUTDOOR COMBUSTION AND …
  28. Appendix K — POTABLE RAINWATER CATCHMENT SYSTEMS
  29. Appendix L — SUSTAINABLE PRACTICES
  30. Appendix M — PEAK WATER DEMAND CALCULATOR

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