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Chapter 4 — RESIDENTIAL MANDATORY MEASURES

Section 4.303 — INDOOR WATER USE

2025 California Green Building Standards Code (Title 24, Part 11) · 2025 edition · updated 2026-07-25 · California

4.303.1 Water conserving plumbing fixtures and fittings. Plumbing fixtures (water closets and urinals) and fittings (faucets and showerheads) shall comply with Sections 4.303.1.1, 4.303.1.2, 4.303.1.3 and 4.303.1.4.

Note: All noncompliant plumbing fixtures in any residential real property shall be replaced with water-conserving plumbing fixtures. Plumbing fixture replacement is required prior to issuance of a certificate of final completion, certificate of occupancy, or final permit approval by the local building department. See Civil Code Section 1101.1, et seq., for the definition of a noncompliant plumbing fixture, types of residential buildings affected and other important enactment dates.

4.303.1.1 Water closets. The effective flush volume of all water closets shall not exceed 1.28 gallons per flush. Tank-type water closets shall be certified to the performance criteria of the US EPA WaterSense Specification for Tank-type Toilets.

Note: The effective flush volume of dual flush toilets is defined as the composite, average flush volume of two reduced flushes and one full flush.

4.303.1.2 Urinals. The effective flush volume of wall-mounted urinals shall not exceed 0.125 gallons per flush. The effective flush volume of all other urinals shall not exceed 0.5 gallons per flush.

4.303.1.3 Showerheads.

4.303.1.3.1 Single showerhead. Showerheads shall have a maximum flow rate of not more than 1.8 gallons per minute at 80 psi. Showerheads shall be certified to the performance criteria of the US EPA WaterSense Specification for Showerheads.

4.303.1.3.2 Multiple showerheads serving one shower. When a shower is served by more than one showerhead, the combined flow rate of all showerheads and/or other shower outlets controlled by a single valve shall not exceed 1.8 gallons per minute at 80 psi, or the shower shall be designed to allow only one shower outlet to be in operation at a time.

Note: A hand-held shower shall be considered a showerhead.

4.303.1.4 Faucets.

4.303.1.4.1 Residential lavatory faucets. The maximum flow rate of residential lavatory faucets shall not exceed 1.2 gallons per minute at 60 psi. The minimum flow rate of residential lavatory faucets shall not be less than 0.8 gallons per minute at 20 psi.

4.303.1.4.2 Lavatory faucets in common and public use areas. The maximum flow rate of lavatory faucets installed in common and public use areas (outside of dwellings or sleeping units) in residential buildings shall not exceed 0.5 gallons per minute at 60 psi.

4.303.1.4.3 Metering faucets. Metering faucets when installed in residential buildings shall not deliver more than 0.2 gallons per cycle.

4.303.1.4.4 Kitchen faucets. The maximum flow rate of kitchen faucets shall not exceed 1.8 gallons per minute at 60 psi. Kitchen faucets may temporarily increase the flow above the maximum rate, but not to exceed 2.2 gallons per minute at 60 psi, and must default to a maximum flow rate of 1.8 gallons per minute at 60 psi.

Note: Where complying faucets are unavailable, aerators or other means may be used to achieve reduction.

4.303.1.4.5 Pre-rinse spray valves. When installed, commercial pre-rinse spray valves shall meet the requirements in the California Plumbing Code, Section 420.3.

4.303.2 Submeters for multifamily buildings and dwelling units in mixed-use residential/commercial buildings. Submeters shall be installed to measure water usage of individual rental dwelling units in accordance with the California Plumbing Code.

4.303.3 Standards for plumbing fixtures and fittings. Plumbing fixtures and fittings shall be installed in accordance with the Cali- fornia Plumbing Code, and shall meet the applicable standards referenced in Table 1701.1 of the California Plumbing Code.

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▸ Contents — 2025 California Green Building Standards Code (Title 24, Part 11)
2025 California Green Building Standards Code (Title 24, Part 11)
  1. Chapter 1 — ADMINISTRATION
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GREEN BUILDING
  4. Chapter 4 — RESIDENTIAL MANDATORY MEASURES
  5. Chapter 4 — RESIDENTIAL MANDATORY MEASURES
  6. ▸ Chapter 4 — RESIDENTIAL MANDATORY MEASURES
    Overview
    1. Section 4.301 — GENERAL
    2. Section 4.302 — DEFINITIONS
    3. Section 4.303 — INDOOR WATER USE
    4. Section 4.304 — OUTDOOR WATER USE
    5. Section 4.305 — WATER REUSE SYSTEMS
  7. Chapter 4 — RESIDENTIAL MANDATORY MEASURES
  8. Chapter 4 — RESIDENTIAL MANDATORY MEASURES
  9. Chapter 5 — NONRESIDENTIAL MANDATORY MEASURES
  10. Chapter 5 — NONRESIDENTIAL MANDATORY MEASURES
  11. Chapter 5 — NONRESIDENTIAL MANDATORY MEASURES
  12. Chapter 5 — NONRESIDENTIAL MANDATORY MEASURES
  13. Chapter 5 — NONRESIDENTIAL MANDATORY MEASURES
  14. Chapter 6 — REFERENCED ORGANIZATIONS AND STANDARDS
  15. Chapter 7 — INSTALLER AND SPECIAL INSPECTOR QUALIFICATIONS
  16. Chapter 8 — COMPLIANCE FORMS, WORKSHEETS AND REFERENCE MATERIAL

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