CALGreen · California Green Building Standards Code (CALGreen)

Indoor fixture requirements, submeters and outdoor potable‑water measures

Q: Can I use captured rainwater indoors for toilets?

Yes, but § A4.303.2 requires that any alternate nonpotable water source used indoors be installed in accordance with the California Plumbing Code — which contains the allowable uses, treatment, and cross‑connection controls you must follow.

Q: If I can't find a kitchen faucet meeting 1.5 gpm, what then?

The code for § A4.303.1 allows the use of aerators or other means to achieve the required reduction when complying faucets are unavailable — document the approach for plan review and inspection.

For homeowners: CALGreen’s Appendix A4 says kitchen faucets must default to a low flow of 1.5 gpm (temporary higher flows allowed only briefly), alternative indoor water sources (like graywater or captured rainwater) must be installed per the California Plumbing Code, and rainwater catchment systems must collect runoff from at least 65% of your roof — check the CPC and your local jurisdiction for installation details and permits.

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

The California Green Building Standards Code requires residential kitchen faucets to limit flow to 1.5 gallons per minute (gpm) at 60 psi (with a short temporary allowance up to 2.2 gpm) under § A4.303.1.
The code encourages use of alternate nonpotable water sources for indoor potable‑water reduction, and requires those systems to be installed in accordance with the California Plumbing Code under § A4.303.2.
For outdoor potable‑water reduction, the code requires an approved rainwater catchment system to be designed and installed to use rainwater generated by at least 65% of the available roof area under § A4.304.1.

The single most important obligation: kitchen faucets must default to 1.5 gpm at 60 psi, alternate indoor nonpotable systems must comply with the California Plumbing Code, and rainwater systems must capture runoff from ≥65% of roof area.

Requirements in detail

Indoor fixtures — kitchen faucets (primary prescriptive rule)

Key rule: § A4.303.1 requires the maximum flow rate of kitchen faucets to be 1.5 gpm at 60 psi. Kitchen faucets may temporarily increase above that rate but must not exceed 2.2 gpm at 60 psi and must default to 1.5 gpm at 60 psi.
Note in the code: if a complying faucet is unavailable, aerators or other means may be used to achieve the reduction called for by the section.

Alternate (nonpotable) indoor water sources

§ A4.303.2 requires that alternate nonpotable water sources are used for indoor potable‑water reduction, and that such systems shall be installed in accordance with the California Plumbing Code (CPC). This covers graywater, captured rainwater used indoors where allowed, or other permitted nonpotable supplies for approved indoor uses. Installation and cross‑connection control follow the CPC.

Outdoor potable‑water measures — rainwater catchment

§ A4.304.1 requires an approved rainwater catchment system that is designed and installed to use rainwater generated by at least 65 percent of the available roof area, and that the system shall be designed and installed in accordance with the California Plumbing Code.

Decision‑relevant dimensions and values (quick reference table)

Item	Requirement / value	Applicability / threshold	Code Reference
Kitchen faucet max flow	1.5 gpm at 60 psi (default) — temporary up to 2.2 gpm allowed	Applies to kitchen faucets in residential voluntary measures	§ A4.303.1
When aerators allowed	Use aerators or other means when complying faucets unavailable	Practical compliance option (note in section)	§ A4.303.1
Alternate nonpotable sources	Must be installed in accordance with the California Plumbing Code	Any alternate nonpotable source used to reduce indoor potable use	§ A4.303.2
Rainwater catchment cover	≥ 65% of available roof area	Rainwater catchment systems serving the building	§ A4.304.1

(Note: the A4 sections quoted above are Appendix A4 voluntary residential measures. For submetering and other mandatory metering rules see the related provisions below.)

Exceptions & special cases

If a complying kitchen faucet model is not available, the code explicitly allows use of aerators or other means to achieve the flow reduction required by § A4.303.1.
§ A4.303.2 does not prescribe specific alternate systems or allowed indoor uses; it defers to the California Plumbing Code for permitted applications, installation standards and cross‑connection control — consult the CPC for details (e.g., when graywater or treated rainwater may be used indoors).
§ A4.304.1 requires design/installation per the CPC; local authority having jurisdiction (AHJ) or local ordinance may impose additional constraints or approvals for rainwater systems (e.g., permits, health‑agency approvals).

If you need specific CPC installation details or local ordinance rules, those are outside these A4 sections and must be looked up in the California Plumbing Code or local rules.

Common mistakes

Assuming the supply may be set to a higher permanent flow: the code allows only a temporary increase up to 2.2 gpm; the faucet must default back to 1.5 gpm per § A4.303.1.
Installing an alternate nonpotable system without following the CPC: § A4.303.2 requires CPC compliance; omission of CPC‑required backflow prevention or treatment is a common compliance failure.
Designing a rainwater catchment that collects from less than 65% of roof area and assuming it meets § A4.304.1 — the code requires capture from at least 65%. Do not substitute a lesser capture area without AHJ approval.

Worked example — concrete scenario

Scenario: New single‑family house with a 2,400 ft² roof area and a kitchen specification.

Kitchen faucet selection (indoor fixture): choose a faucet that defaults to 1.5 gpm at 60 psi. The installer may accept a faucet that can temporarily open to 2.2 gpm for cleaning tasks, but the device must revert to 1.5 gpm by default. This meets § A4.303.1.
Rainwater catchment sizing (outdoor potable‑water measure): the system must be designed to use rainwater generated by at least 65% of the available roof area. For a 2,400 ft² roof, 0.65 × 2,400 = 1,560 ft² must be included in the catchment area per § A4.304.1. Design and install the system per the California Plumbing Code (filtering, piping, overflow, and any required treatment).
Alternate indoor nonpotable source: if the project intends to supply toilets or other allowed indoor uses from captured rainwater or graywater, the system must be installed in accordance with the CPC and local AHJ rules, per § A4.303.2. Confirm permitted indoor uses and required fittings/backflow preventers in the CPC.

Note about submeters (user topic): Appendix A4 voluntary sections above do not prescribe general submetering rules in A4.303.1–A4.304.1. Submetering requirements do appear elsewhere in CALGreen (for example, mandatory Section 4.303.2 addresses submeters for multifamily units and 5.303.1 addresses submeters in large nonresidential buildings). If your project needs submeter compliance, consult § 4.303.2 and § 5.303.1 for the specific submetering triggers and thresholds.

Related provisions (quick pointers)

§ 4.303.1 — Mandatory residential plumbing fixture flow‑rates and fixtures (see mandatory sections for required flow rates for other fixtures).
§ 4.303.2 — Submeters for multifamily buildings and dwelling units in mixed‑use buildings (submetering requirements for rental units).
§ 5.303.1 — Nonresidential submetering thresholds and where separate submeters are required (large buildings, high‑use tenants).
§ A4.304.3 — Landscape water meters for new water service connections and landscaped irrigated areas (outdoor metering for small landscapes).
California Plumbing Code (CPC) — referenced repeatedly by § A4.303.2 and § A4.304.1 for installation, treatment, and cross‑connection control (consult CPC for technical design and approval criteria).

Code references

Grounded in the retrieved California Green Building Standards Code (CALGreen) — click a citation to read the verbatim passage:

CALGreen § 303.1 High relevance — show source text
2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A4-11

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APPENDIX A4-12 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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A4 RESIDENTIAL VOLUNTARY MEASURES

DIVISION A4.3 – WATER EFFICIENCY AND CONSERVATION

SECTION A4.301—GENERAL (RESERVED)

SECTION A4.302—DEFINITIONS (RESERVED)

SECTION A4.303—INDOOR WATER USE

A4.303.1 Kitchen faucets. The maximum flow rate of kitchen faucets shall not exceed 1.5 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 1.5 gallons per minute at 60 psi.

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

A4.303.2 Alternate water sources for nonpotable applications. Alternate nonpotable water sources are used for indoor potable water reduction. Alternate nonpotable water sources shall be installed in accordance with the California Plumbing Code.

A4.303.3 Appliances. Install at least one qualified ENERGY STAR dishwasher or clothes washer.

Note: See Section A5.303.3 for nonresidential dishwashers and clothes washers.

A4.303.4 Nonwater urinals and waterless toilets. Nonwater urinals or composting toilets are installed.

Where approved, nonwater urinals with drain cleansing action (formerly hybrid urinals), as defined in Chapter 2, shall be considered nonwater urinals.

A4.303.5 Hot water recirculation systems. One- and two-family dwellings shall be equipped with a demand hot water recirculation system, as defined in Chapter 2. The demand hot water recirculation system shall be installed in accordance with the California Plumbing Code, California Energy Code and the manufacturer’s installation instructions.

SECTION A4.304—OUTDOOR WATER USE

A4.304.1 Rainwater catchment systems. An approved rainwater catchment system is designed and installed to use rainwater generated by at least 65 percent of the available roof area. Rainwater catchment systems shall be designed and installed in accordance with the California Plumbing Code.

A4.304.2 Potable water elimination. When landscaping is provided and as allowed by local ordinance, a water efficient landscape irrigation design that eliminates the use of potable water beyond the initial requirements for plant installation and establishment shall be provided. Methods used to accomplish the requirements of this section shall comply with the requirements of the California Building Standards Code and shall include, but not be limited to, the following:
1. Use of captured rainwater.
2. Use of recycled water.
3. Water treated for irrigation purposes and conveyed by a water district or public entity.
4. Use of graywater.
5. Use of drought tolerant plants.
A4.304.3 Landscape water meters. For new water service connections, landscaped irrigated areas less than 5,000 square feet shall be provided with separate submeters or metering devices for outdoor potable water use.
CALGreen § 4.303.3 High relevance — show source text
** Submeters shall be
installed to measure water usage of individual rental dwelling units in
accordance with the_California Plumbing Code.||||||| |4.303.3Plumbing fixtures and fittings required in Section 4.303.1
shall be installed in accordance with the_California Plumbing Code,
and shall meet the applicable referenced standards.||||||| |A4.303.1The maximum flow rate of kitchen faucets shall not exceed
1.5 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 1.5 gallons per minute at 60 psi.
**Note:**Where complying faucets are unavailable, aerators or other
means may be used to achieve reduction.||||||| |4.303.1.4.3 Metering faucets in residential buildings shall not deliver
more than 0.2 gallons per cycle.||||||| |A4.303.2Alternate water source for nonpotable applications.
Alternate nonpotable water sources are used for indoor potable water
reduction. Alternate nonpotable water sources shall be installed in
accordance with the_California Plumbing Code._||||||| |A4.303.3 Install at least one qualified ENERGY STAR dishwasher or
clothes washer.||
|
|
|
|
| |A4.303.4Nonwater urinals or waterless toilets are installed.||||||| |A4.303.5One- and two-family dwellings shall be equipped with a
demand hot water recirculation system.||||||| |Outdoor Water Use||||||| |4.304.1 Residential developments shall comply with a local water
efficient landscape ordinance or the current California Department of
Water Resources’ Model Water Efficient Landscape Ordinance
(MWELO), whichever is more stringent.||||||| |A4.304.1A rainwater capture, storage and re-use system is designed
and installed.||||||| |A4.304.2A landscape design is installed, which does not utilize
potable water.||||||| |A4.304.3 For new water service connections, landscaped irrigated
areas less than 5,000 square feet shall be provided with separate
submeters or metering devices for outdoor potable water use.
CALGreen § 303.3 High relevance — show source text
303.3** Install at least one qualified ENERGY STAR dishwasher or
clothes washer.||
|
|
|
|
| |A4.303.4Nonwater urinals or waterless toilets are installed.||||||| |A4.303.5One- and two-family dwellings shall be equipped with a
demand hot water recirculation system.||||||| |Outdoor Water Use||||||| |4.304.1 Residential developments shall comply with a local water
efficient landscape ordinance or the current California Department of
Water Resources’ Model Water Efficient Landscape Ordinance
(MWELO), whichever is more stringent.||||||| |A4.304.1A rainwater capture, storage and re-use system is designed
and installed.||||||| |A4.304.2A landscape design is installed, which does not utilize
potable water.||||||| |A4.304.3 For new water service connections, landscaped irrigated
areas less than 5,000 square feet shall be provided with separate
submeters or metering devices for outdoor potable water use.||||||| |Water Reuse Systems||||||| |A4.305.1Piping is installed to permit future use of a graywater
irrigation system served by the clothes washer or other fixtures.||
|
|
|
|
| |A4.305.2 Recycled water piping is installed.||
|
|
|
|
| |A4.305.3Recycled water is used for landscape irrigation.||||||| |Innovative Concepts and Local Environmental Conditions||||||| |A4.306.1Items in this section are necessary to address innovative
concepts or local environmental conditions.||||||| |Item 1|
|
|
|
|
|
| |Item 2|
|
|
|
|
|
| |Item 3|||||||

APPENDIX A4-26 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE
CALGreen § 303.4 High relevance — show source text
APPENDIX A5 — NONRESIDENTIAL VOLUNTARY MEASURES

A5.303.4 Water conserving plumbing fixtures and fittings.

A5.303.4.1 Nonwater urinals. Nonwater urinals with drain cleansing action are installed in accordance with the California Plumbing Code .

Where approved, nonwater urinals with drain cleansing action (formerly urinal, hybrids) as defined in Chapter 2, shall be considered waterless urinals.

A5.303.5 Dual plumbing. New buildings and facilities shall be dual plumbed for potable and recycled water systems for toilet flushing when recycled water is available as determined by the enforcement authority.

SECTION A5.304—OUTDOOR WATER USE

A5.304.1 Reserved.

A5.304.2 Outdoor water use. For new water service not subject to the provisions of Water Code Section 535, separate meters or submeters shall be installed for indoor and outdoor potable water use for landscaped areas of at least 500 square feet but not more than 1,000 square feet.

A5.304.6 Restoration of areas disturbed by construction. Restore all landscape areas disturbed during construction by planting with local adaptive and/or noninvasive vegetation.

A5.304.7 Previously developed sites. On previously developed or graded sites, restore or protect at least 50 percent of the site area with adaptive and/or noninvasive vegetation. Projects complying with Section A5.106.3, Item 3 may apply vegetated roof surface to this calculation if the roof plants meet the definition of adaptive and noninvasive.

Exception: Area of the building footprint is excluded from the calculation.

A5.304.8 Graywater irrigation system. Install a graywater collection system for onsite subsurface irrigation using graywater collected from bathtubs, showers, bathroom wash basins and laundry water. See California Plumbing Code.

SECTION A5.305—WATER REUSE

A5.305.1 Nonpotable water systems. Nonpotable water systems for indoor and outdoor use shall comply with the current edition of the California Plumbing Code.

A5.305.2 Irrigation systems. Irrigation systems regulated by a local water efficient landscape ordinance or by the California Department of Water Resources Model Water Efficient Landscape Ordinance (MWELO) shall use recycled water.

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APPENDIX A5-22 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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CALIFORNIA GREEN BUILDING STANDARDS CODE – MATRIX ADOPTION TABLE

APPENDIX A5 – NONRESIDENTIAL VOLUNTARY MEASURES

DIVISION A5.4 – MATERIAL CONSERVATION AND RESOURCE EFFICIENCY

(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
CALGreen § 2.6 High relevance — show source text
70 (2.6 L)|≤ 0.79 (3 L)| |Multiple Tank Conveyor|≤ 0.54 (2 L)|≤ 0.54 (2 L)| |Stationary Single Tank Door|≤ 0.89 (3.4 L)|≤ 1.18 (4.5 L)| |Under Counter|≤ 0.86 (3.3 L)|≤ 1.19 (4.5 L)| |Pot, Pan and Utensil|≤ 0.58 GPSF|≤ 0.58 GPSF| |Single Tank Flight Type|GPH ≤ 2.975x + 55.00|GPH ≤ 2.975x + 55.00| |Multiple Tank Flight Type|GPH ≤ 4.96x + 17.00|GPH ≤ 4.96x + 17.00| |Note: GPSF = gallons per square foot of rack; GPH = gallons per hour;
X = square feet of conveyor belt/minute (max conveyor speed sf/min as tested and certified to NSF/ANSI Standard 3)|Note: GPSF = gallons per square foot of rack; GPH = gallons per hour;
X = square feet of conveyor belt/minute (max conveyor speed sf/min as tested and certified to NSF/ANSI Standard 3)|Note: GPSF = gallons per square foot of rack; GPH = gallons per hour;
X = square feet of conveyor belt/minute (max conveyor speed sf/min as tested and certified to NSF/ANSI Standard 3)|

APPENDIX A5-20 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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APPENDIX A5 — NONRESIDENTIAL VOLUNTARY MEASURES

A5.303.4 Water conserving plumbing fixtures and fittings.

A5.303.4.1 Nonwater urinals. Nonwater urinals with drain cleansing action are installed in accordance with the California Plumbing Code .

Where approved, nonwater urinals with drain cleansing action (formerly urinal, hybrids) as defined in Chapter 2, shall be considered waterless urinals.

A5.303.5 Dual plumbing. New buildings and facilities shall be dual plumbed for potable and recycled water systems for toilet flushing when recycled water is available as determined by the enforcement authority.

SECTION A5.304—OUTDOOR WATER USE

A5.304.1 Reserved.

A5.304.2 Outdoor water use. For new water service not subject to the provisions of Water Code Section 535, separate meters or submeters shall be installed for indoor and outdoor potable water use for landscaped areas of at least 500 square feet but not more than 1,000 square feet.

A5.304.6 Restoration of areas disturbed by construction. Restore all landscape areas disturbed during construction by planting with local adaptive and/or noninvasive vegetation.

A5.304.7 Previously developed sites. On previously developed or graded sites, restore or protect at least 50 percent of the site area with adaptive and/or noninvasive vegetation. Projects complying with Section A5.106.3, Item 3 may apply vegetated roof surface to this calculation if the roof plants meet the definition of adaptive and noninvasive.

Exception: Area of the building footprint is excluded from the calculation.
CALGreen § 5.303 High relevance — show source text
GRAYWATER.

METERING FAUCET.

MODEL WATER EFFICIENT LANDSCAPE ORDINANCE (MWELO).

POTABLE WATER.

SPECIAL LANDSCAPE AREA (SLA). [DSA-SS]

SUBMETER.

SECTION 5.303—INDOOR WATER USE

5.303.1 Meters. Separate submeters or metering devices shall be installed for the uses described in Sections 5.303.1.1 and 5.303.1.2. 5.303.1.1 New buildings or additions in excess of 50,000 square feet. Separate submeters shall be installed as follows:
1. For each individual leased, rented or other tenant space within the building projected to consume more than 100 gal/day (380 L/day), including, but not limited to, spaces used for laundry or cleaners, restaurant or food service, medical or dental office, laboratory, or beauty salon or barber shop.
2. Where separate submeters for individual building tenants are unfeasible, for water supplied to the following subsystems: a. Makeup water for cooling towers where flow through is greater than 500 gpm (30 L/s). b. Makeup water for evaporative coolers greater than 6 gpm (0.04 L/s). c. Steam and hot-water boilers with energy input more than 500,000 Btu/h (147 kW). 5.303.1.2 Excess consumption. A separate submeter or metering device shall be provided for any tenant within a new building or within an addition that is projected to consume more than 1,000 gal/day.
5.303.2 Reserved.

5.303.3 Water conserving plumbing fixtures and fittings. Plumbing fixtures (water closets and urinals) and fittings (faucets and showerheads) shall comply with the following: 5.303.3.1 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.

5.303.3.2 Urinals.

5.303.3.2.1 Wall-mounted urinals. The effective flush volume of wall-mounted urinals shall not exceed 0.125 gallons per flush.

5.303.3.2.2 Floor-mounted urinals. The effective flush volume of floor-mounted or other urinals shall not exceed 0.5 gallons per flush.

5.303.3.3 Showerheads.

5.303.3.3.1 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. 5.303.3.3.2 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.

5.303.3.4 Faucets and fountains.
CALGreen § 4.303.1.4.3 High relevance — show source text
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.

SECTION 4.304—OUTDOOR WATER USE

4.304.1 Outdoor potable water use in landscape areas. Residential developments shall comply with a local water efficient landscape ordinance or the current California Department of Water Resources’ Model Water Efficient Landscape Ordinance (MWELO), whichever is more stringent.

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RESIDENTIAL MANDATORY MEASURES

Notes:
1. The Model Water Efficient Landscape Ordinance (MWELO) is located in the California Code of Regulations, Title 23, Chapter 2.7, Division 2.
MWELO and supporting documents, including a water budget calculator, are available at: https://www.water.ca.gov/

SECTION 4.305—WATER REUSE SYSTEMS (RESERVED)

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4 RESIDENTIAL MANDATORY MEASURES

DIVISION 4.4 – MATERIAL CONSERVATION AND RESOURCE EFFICIENCY

SECTION 4.401—GENERAL

4.401.1 Scope. The provisions of this chapter shall outline means of achieving material conservation and resource efficiency through protection of buildings from exterior moisture; construction waste diversion; employment of techniques to reduce pollution through recycling of materials; and building commissioning or testing, adjusting and balancing.

SECTION 4.402—DEFINITIONS

4.402.1 Definitions. Reserved.

SECTION 4.403 —FOUNDATION SYSTEMS (RESERVED)

SECTION 4.404—EFFICIENT FRAMING TECHNIQUES (RESERVED)

SECTION 4.405—MATERIAL SOURCES (RESERVED)

SECTION 4.406—ENHANCED DURABILITY AND REDUCED MAINTENANCE
CALGreen § 301.1 High relevance — show source text
301.1||||||||X||||||||||||||| |5.302.1 Definitions||||||||X||||||||||||||| |5.303.3.1||||||||X||||||||||||||| |5.303.3.2||||||||X||||||||||||||| |5.303.3.3||||||||X||||||||||||||| |5.303.3.4||||||||X||||||||||||||| |5.303.6||||||||X||||||||||||||| |5.304.6 and subsections||†||||||X|||||||||||||||

The state agency does not adopt sections identified by the following symbol: †.

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5-18 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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5 NONRESIDENTIAL MANDATORY MEASURES

DIVISION 5.3 – WATER EFFICIENCY AND CONSERVATION

SECTION 5.301—GENERAL

5.301.1 Scope. The provisions of this chapter shall establish the means of conserving water used indoors, outdoors and in wastewater conveyance.

SECTION 5.302—DEFINITIONS

5.302.1 Definitions. The following terms are defined in Chapter 2. EVAPOTRANSPIRATION ADJUSTMENT FACTOR (ETAF).

GRAYWATER.

METERING FAUCET.

MODEL WATER EFFICIENT LANDSCAPE ORDINANCE (MWELO).

POTABLE WATER.

SPECIAL LANDSCAPE AREA (SLA). [DSA-SS]

SUBMETER.

SECTION 5.303—INDOOR WATER USE

5.303.1 Meters. Separate submeters or metering devices shall be installed for the uses described in Sections 5.303.1.1 and 5.303.1.2. 5.303.1.1 New buildings or additions in excess of 50,000 square feet. Separate submeters shall be installed as follows:
1. For each individual leased, rented or other tenant space within the building projected to consume more than 100 gal/day (380 L/day), including, but not limited to, spaces used for laundry or cleaners, restaurant or food service, medical or dental office, laboratory, or beauty salon or barber shop.
2. Where separate submeters for individual building tenants are unfeasible, for water supplied to the following subsystems: a. Makeup water for cooling towers where flow through is greater than 500 gpm (30 L/s). b. Makeup water for evaporative coolers greater than 6 gpm (0.04 L/s). c. Steam and hot-water boilers with energy input more than 500,000 Btu/h (147 kW). 5.303.1.2 Excess consumption. A separate submeter or metering device shall be provided for any tenant within a new building or within an addition that is projected to consume more than 1,000 gal/day.
5.303.2 Reserved.

CALGreen § 4.303.1 High relevance — show source text

APPENDIX A4 — RESIDENTIAL VOLUNTARY MEASURES

SECTION A4.602—RESIDENTIAL OCCUPANCIES APPLICATION CHECKLIST—continued

FEATURE OR MEASURE	LEVELS APPLICANT TO SELECT ELECTIVE MEASURES	Col3	Col4	VERIFICATIONS ENFORCING AGENCY TO SPECIFY VERIFICATION METHOD	Col6	Col7
FEATURE OR MEASURE	Mandatory	Prerequisites and electives1	Prerequisites and electives1	Enforcing Agency  All	Installer or Designer  All	Third party  All
FEATURE OR MEASURE	Mandatory	Tier 1	Tier 2	Tier 2	Tier 2	Tier 2
WATER EFFICIENCY AND CONSERVATION
Indoor Water Use
4.303.1Plumbing fixtures (water closets and urinals) and fittings (showerheads, faucets and pre-rinse spray valves) installed in residential buildings shall comply with the prescriptive requirements of Sections 4.303.1.1 through 4.303.1.4.5.						
4.303.2 Submeters for multifamily building 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._						
4.303.3Plumbing fixtures and fittings required in Section 4.303.1 shall be installed in accordance with the_California Plumbing Code,_ and shall meet the applicable referenced standards.						
A4.303.1The maximum flow rate of kitchen faucets shall not exceed 1.5 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 1.5 gallons per minute at 60 psi. Note:Where complying faucets are unavailable, aerators or other means may be used to achieve reduction.						
4.303.1.4.3 Metering faucets in residential buildings shall not deliver more than 0.2 gallons per cycle.						
A4.303.2Alternate water source for nonpotable applications. Alternate nonpotable water sources are used for indoor potable water reduction. Alternate nonpotable water sources shall be installed in accordance with the_California Plumbing Code._						
**A4.303.

CALGreen § 303.5 High relevance — show source text
Where approved, nonwater urinals with drain cleansing action (formerly hybrid urinals), as defined in Chapter 2, shall be considered nonwater urinals.

A4.303.5 Hot water recirculation systems. One- and two-family dwellings shall be equipped with a demand hot water recirculation system, as defined in Chapter 2. The demand hot water recirculation system shall be installed in accordance with the California Plumbing Code, California Energy Code and the manufacturer’s installation instructions.

SECTION A4.304—OUTDOOR WATER USE

A4.304.1 Rainwater catchment systems. An approved rainwater catchment system is designed and installed to use rainwater generated by at least 65 percent of the available roof area. Rainwater catchment systems shall be designed and installed in accordance with the California Plumbing Code.

A4.304.2 Potable water elimination. When landscaping is provided and as allowed by local ordinance, a water efficient landscape irrigation design that eliminates the use of potable water beyond the initial requirements for plant installation and establishment shall be provided. Methods used to accomplish the requirements of this section shall comply with the requirements of the California Building Standards Code and shall include, but not be limited to, the following:
1. Use of captured rainwater.
2. Use of recycled water.
3. Water treated for irrigation purposes and conveyed by a water district or public entity.
4. Use of graywater.
5. Use of drought tolerant plants.
A4.304.3 Landscape water meters. For new water service connections, landscaped irrigated areas less than 5,000 square feet shall be provided with separate submeters or metering devices for outdoor potable water use.

SECTION A4.305 —WATER REUSE SYSTEMS

A4.305.1 Graywater. Alternative plumbing piping is installed to permit the discharge from the clothes washer or other fixtures to be used for an irrigation system in compliance with the California Plumbing Code.

A4.305.2 Recycled water piping. Based on projected availability, dual water piping is installed for future use of recycled water at the following locations:
1. Interior piping for the use of recycled water is installed to serve all water closets, urinals and floor drains.
2. Exterior piping is installed to transport recycled water from the point of connection to the structure. Recycled water systems shall be designed and installed in accordance with the California Plumbing Code.
A4.305.3 Recycled water for landscape irrigation. Recycled water is used for landscape irrigation.

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APPENDIX A4 — RESIDENTIAL VOLUNTARY MEASURES

SECTION A4.306 —INNOVATIVE CONCEPTS AND LOCAL ENVIRONMENTAL CONDITIONS

A4.306.1 Innovative concepts and local environmental conditions. The provisions of this code are not intended to prevent the use of any alternate material, appliance, installation, device, arrangement, method, design or method of construction not specifically prescribed by this code. This code does not limit the authority of city, county, or city and county government to make necessary changes to the provisions contained in this code pursuant to Section 101.7.1.

APPENDIX A4-14 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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CALGreen § 203.1.2.1 Medium relevance — show source text

In addition, a minimum of two of
the efficiency measures specified in Sections A4.203.1.2.1 through
A4.203.1.2.8 will be required to be met.
· Roof Deck Insulation or Ducts in Conditioned Space.
· High-performance Walls.
· Compact Hot Water Distribution System.
· Drain Water Heat Recovery.
· High Performance Vertical Fenestration.
· Heat Pump Water Heater Demand Management.
· Battery Storage System Controls.
· **Heat Pump Space and Water Heating.||2|2|||| |**A4.203.1.3 Consultation with local electric service provider.**Local
jurisdictions considering adoption of reduced EDR targets based on
using solar photovoltaic (PV) systems larger than required by the
California Energy Code shall consult with the local electric service
provider to ensure that that PV system sizing required to comply with
the EDR targets will be acceptable to the local electric service
provider.||2|2||||

2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A4-25

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

APPENDIX A4 — RESIDENTIAL VOLUNTARY MEASURES

SECTION A4.602—RESIDENTIAL OCCUPANCIES APPLICATION CHECKLIST—continued

FEATURE OR MEASURE	LEVELS APPLICANT TO SELECT ELECTIVE MEASURES	Col3	Col4	VERIFICATIONS ENFORCING AGENCY TO SPECIFY VERIFICATION METHOD	Col6	Col7
FEATURE OR MEASURE	Mandatory	Prerequisites and electives1	Prerequisites and electives1	Enforcing Agency  All	Installer or Designer  All	Third party  All
FEATURE OR MEASURE	Mandatory	Tier 1	Tier 2	Tier 2	Tier 2	Tier 2
WATER EFFICIENCY AND CONSERVATION
Indoor Water Use
4.303.1Plumbing fixtures (water closets and urinals) and fittings (showerheads, faucets and pre-rinse spray valves) installed in residential buildings shall comply with the prescriptive requirements of Sections 4.303.1.1 through 4.303.1.4.5.						
4.303.2 Submeters for multifamily building and dwelling units in **mixed-use residential/commercial buildings.

CALGreen § 3.1. Medium relevance — show source text
1. From Division A4.3, Water Efficiency and Conservation. 3.1. Comply with at least two elective measures selected from Division A4.3.
2. From Division A4.4, Material Conservation and Resource Efficiency. 4.1. Comply with the 20 percent cement reduction requirements in Section A4.403.2. 4.2. Comply with the 10 percent recycled content requirements in Section A4.405.3.1. 4.3. Comply with the 65 percent reduction in construction waste in Section A4.408.1. 4.4. Comply with at least two elective measures selected from Division A4.4.
3. From Division A4.5, Environmental Quality. 5.1. Comply with the 90 percent resilient flooring systems requirements in Section A4.504.2. 5.2. Comply with the thermal insulation requirements for Tier 1 in Section A4.504.3. 5.3. Comply with at least one elective measure selected from Division A4.5.
Note: The Residential Occupancies Application Checklist contained in Section A4.602 may be used to show which elective measures are selected.

A4.601.5 Tier 2. To achieve Tier 2 status a project must comply with the following.

Note: The measures necessary to achieve Tier 2 status are very stringent. Cities, counties, and cities and counties considering adoption of Tier 2 as mandatory should carefully consider the stringency of each measure and ensure that the measures are achievable in their location.

A4.601.5.1 Mandatory measures for Tier 2. The project shall meet or exceed all of the mandatory measures in Chapter 4, Divisions 4.1 through 4.5 and Chapter 7 as applicable.

A4.601.5.2 Prerequisite and elective measures for Tier 2. In addition to the mandatory measures, compliance with the following prerequisite and elective measures from Appendix A4 is also required to achieve Tier 2 status.
1. From Division A4.1, Planning and Design.
2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A4-21

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APPENDIX A4 — RESIDENTIAL VOLUNTARY MEASURES

1.1. Comply with the topsoil protection requirements for Tier 1 and Tier 2 in Section A4.106.2.3. 1.2. Comply with the 30 percent permeable paving requirements in Section A4.106.4. 1.3. Comply with the cool roof requirements in Section A4.106.5. 1.4. Comply with the Tier 2 electric vehicle (EV) charging requirements in Section A4.106.8. 1.5. Comply with at least four elective measures selected from Division A4.1. 2. From Division A4.2, Energy Efficiency. 2.1. For newly constructed low-rise residential buildings, comply with the energy efficiency requirements in Sections A4.203.1, A4.203.1.1, Table A4.203.1.1, A4.203.1.2 and A4.203.1.3.
1. From Division A4.3, Water Efficiency and Conservation. 3.1. Comply with at least three elective measures selected from Division A4.3.
2. From Division A4.4, Material Conservation and Resource Efficiency. 4.1.

Frequently asked questions

Are the kitchen faucet flow limits mandatory or voluntary?

Under Appendix A4 those kitchen faucet limits are part of the A4 voluntary residential measures and are written in § A4.303.1. Local jurisdictions adopting A4 or requiring the voluntary measures will enforce them; otherwise consult the mandatory chapters for requirements that apply in your jurisdiction.

Can I use captured rainwater indoors for toilets?

Yes, but § A4.303.2 requires that any alternate nonpotable water source used indoors be installed in accordance with the California Plumbing Code — which contains the allowable uses, treatment, and cross‑connection controls you must follow.

What exactly does “use rainwater generated by at least 65% of the available roof area” mean?

It means the catchment piping/collection must be sized and located such that rainfall from at least 65% of the total roof area is directed to the approved rainwater catchment system required by § A4.304.1. For a 2,400 ft² roof, that is ≥1,560 ft².

Where are submeter rules in CALGreen?

Submetering provisions appear in other sections of CALGreen: e.g., § 4.303.2 (multifamily dwelling units) and § 5.303.1 (nonresidential meters). The A4 sections you asked about (A4.303.1 / A4.303.2 / A4.304.1) do not set general submetering thresholds — see those other sections for submeter triggers.

If I can't find a kitchen faucet meeting 1.5 gpm, what then?

The code for § A4.303.1 allows the use of aerators or other means to achieve the required reduction when complying faucets are unavailable — document the approach for plan review and inspection.

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Related in the CALGreen

Construction waste management plans and diversion percentage requirements

Cement reduction and recycled content thresholds for Tier 1/Tier 2

Graywater/recycled‑water piping requirements and rainwater capture provisions

Divisions A4.3 & A4.4 — Water Efficiency, Material Conservation & Waste

California Green Building Standards Code (CALGreen)