CALGreen · California Green Building Standards Code (CALGreen)

Rainwater capture, graywater/recycled water piping and waterwise landscape measures

Q: Can I count gutter/downspout area toward the 65% roof capture requirement?

Yes — the code measures the available roof area used by the system. The catchment must be designed to use rainwater generated by at least 65 percent of that area per § A4.304.1 . Design specifics (leaders, gutters, roof washers) follow the California Plumbing Code. file

Q: Does CALGreen force me to stop using potable water for irrigation?

No — § A4.304.2 requires a water‑efficient landscape design that eliminates potable irrigation beyond initial establishment only “as allowed by local ordinance.” Check your local water and planning ordinances before assuming elimination is mandatory.

Q: If recycled water isn’t available now, do I still need to do anything?

Yes — § A4.305.2 requires installing dual piping for future recycled water based on projected availability ; if recycled water is not expected, the requirement may not apply. Consult the local water agency/enforcing authority.

CALGreen says: design rainwater capture to collect runoff from at least 65% of your roof, provide plumbing for future graywater irrigation from clothes washers, and install dual piping where recycled water is projected to be available — all installations must follow the California Plumbing Code and local ordinances. file

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Last reviewed: July 6, 2026

What the code requires — plain English

The California Green Building Standards (CALGreen) requires that an approved rainwater catchment system be sized and installed to capture rain from at least 65 percent of the available roof area (§ A4.304.1) and that landscape designs eliminate the use of potable water after plant establishment where allowed by local ordinance (methods include captured rainwater, recycled water, and graywater) (§ A4.304.2). CALGreen also requires that plumbing be roughed in for future graywater irrigation from clothes washers/other fixtures (§ A4.305.1) and that dual piping for future recycled-water service be installed to specified interior and exterior locations when projected recycled water availability exists (§ A4.305.2).

Capture at least 65% of your roof for a rainwater system and provide piping for future graywater/recycled water so landscapes can avoid potable irrigation once allowed by local ordinance.

Requirements in detail

Rainwater capture (what to design and install)

What: An approved rainwater catchment system designed and installed to use rainwater generated by at least 65 percent of the available roof area. § A4.304.1.
How: Systems must be designed/installed in accordance with the California Plumbing Code (definitions and components such as cisterns, roof washers, etc., are in the Plumbing Code).

Potable-water elimination for landscape irrigation

What: Where landscaping is provided and as allowed by local ordinance, use a water‑efficient landscape design that eliminates the use of potable water beyond the initial establishment period. Methods listed include captured rainwater, recycled water, water treated and delivered by a water district, graywater, and drought‑tolerant plants. § A4.304.2.

Graywater piping (future readiness)

What: Install alternative plumbing piping (i.e., roughed‑in or dedicated piping) to permit discharge from the clothes washer or other fixtures to be used later for irrigation, in compliance with the California Plumbing Code. § A4.305.1.

Recycled water piping (dual piping for future recycled supply)

What: Based on projected availability, install dual water piping for future recycled water at these locations:
1. Interior piping to serve all water closets, urinals and floor drains.
2. Exterior piping to transport recycled water from the point of connection to the structure. Systems must comply with the California Plumbing Code. § A4.305.2.

Decision-relevant quick reference table

Decision / value	What to provide	Key threshold/target	Code Reference
Rain capture area	Capture rain from roof	≥ 65% of available roof area	§ A4.304.1
Potable elimination methods	Provide non‑potable sources or drought‑tolerant plants	Eliminate potable irrigation after establishment (where local ordinance allows)	§ A4.304.2
Graywater future piping	Rough-in alternative piping for laundry/other fixtures	Permit later use for irrigation (per CPC)	§ A4.305.1
Recycled water dual piping — interior	Dual plumb toilets/urinals/floor drains	Serve all water closets, urinals, floor drains	§ A4.305.2 (1)
Recycled water dual piping — exterior	Dual piping from connection to structure	From point of connection to structure	§ A4.305.2 (2)

Note: All system designs/installs must follow the California Plumbing Code (e.g., definitions for rainwater systems, reclaimed/recycled water and cross‑connection protections).

Exceptions & special cases

Local ordinance controls potable‑elimination authority: § A4.304.2 applies only “as allowed by local ordinance” — always check local municipal code before assuming potable elimination is required or permitted.
Recycled water piping is required only “based on projected availability” — the enforcing authority or water agency may determine whether recycled water service is expected. § A4.305.2.
Design and installation details (treatment, cross‑connection control, marking, appurtenances, hose‑bib limitations, testing) are handled by the California Plumbing Code; follow those rules for safe separation and labeling of nonpotable systems. file

Common mistakes

Designing a capture system for less than 65% of roof area or not documenting the capture area — noncompliant with § A4.304.1.
Installing graywater “temporary” piping that cannot be separated/converted per plumbing code — § A4.305.1 requires piping to permit compliant future use.
Omitting dual piping to all required interior fixtures (toilets, urinals, floor drains) — § A4.305.2 specifies those interior locations.
Ignoring cross‑connection, labeling, or hose‑bibb rules in the Plumbing Code (e.g., hose bibbs are restricted on recycled systems; quick‑couplers and signage are required) — can create public‑health violations.
Assuming potable elimination is mandatory everywhere — potable elimination is conditioned on local ordinance under § A4.304.2.

Worked example — concrete scenario

Scenario: Single‑family house with a 2,000 ft² roof and a planned landscape that the owner wants to irrigate with captured rainwater in the future.

Rain capture sizing per § A4.304.1: required capture area = 2,000 ft² × 65% = 1,300 ft² of roof area connected to the catchment system. Document which roof planes provide that 1,300 ft².
Graywater readiness per § A4.305.1: provide alternative plumbing (laundry outlet piping routed or stubbed) so the clothes washer discharge can later be connected to an irrigation subsystem compliant with the California Plumbing Code. Note: do not install an improperly separated or temporary connection — install per CPC specifications. file
Recycled water dual piping per § A4.305.2 (if your water agency projects recycled water availability): install an additional nonpotable supply line to the building for future use, and ensure interior piping is installed to serve every toilet, urinal and floor drain. Outside, install dual piping from the point where recycled water will connect on the property to the structure. Follow CPC cross‑connection and labeling rules when installing. file

(You may still need to size tanks, filters, first‑flush devices and irrigation storage based on local rainfall and irrigation demand — those design details are covered by the California Plumbing Code and good engineering practice, not CALGreen’s § A4 text.)

Related provisions (CALGreen & referenced codes)

§ A4.304.3 — separate submeters for outdoor potable water use for new service connections under certain area thresholds (see CALGreen Appendix A4).
§ A4.305.3 — recycled water used for landscape irrigation (related statement in Appendix A4).
California Plumbing Code — definitions and detailed requirements for rainwater catchment systems, recycled (reclaimed) water, cross‑connection testing, signage, and appurtenances (referenced throughout §§ A4.304 and A4.305). file
CALGreen water‑resilience/roof drainage details (e.g., routing gutters to rainwater or landscape drains) — see § A4.407.2.

Code references

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

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.

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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 § 303.3 High relevance — show source text
303.3** Install at least one qualified ENERGY STAR dishwasher or
clothes washer.||
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| |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.||
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| |A4.305.2 Recycled water piping is installed.||
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| |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
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APPENDIX A4-26 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE
CALGreen § 301.1 High relevance — show source text
Voluntary Measures 301.1, 306 Voluntary Tiers 304, 305, 306, A4.601, A5.601

Water Resistance and Moisture Management 5.407, 5.505, A4.407, Appendix A6.1 (OSHPD) A5.407 Moisture control 4.505, 5.407.2, 5.505, Appendix A6.1 (OSHPD) A5.407.9, Appendix A6.1 (OSHPD) A5.505.2 Weather protection 5.407.1, A5.407.3

Water Reuse Systems A4.305 Graywater A4.305.1, A5.304.8 Recycled water for landscape irrigation A4.305.3 Recycled water piping A4.305.2 Water Use, Indoor 4.303, 5.303, A4.303, A5.203

Appliances A4.303.3, A5.303.3, Appendix A6.1 (OSHPD) A5.210 Dual plumbing A5.303.5 Fixture flow rates 4.303.1, Table A5.303.2.3.1, 5.303.2.3.1, A4.303 Kitchen faucets and dishwashers

A4.303.1

Meters 4.303.2, 5.303.1 Multiple showerheads serving one shower 4.303.1.3.2, 5.303.3.3.2 Nonwater urinals and waterless toilets

A4.303.4, A5.303.4.1 Plumbing fixtures and fittings 4.303.1, 4.303.2, 5.303.3, 5.303.6 Tier 1, 12% savings; Tier 2, 20% savings; and 25% savings A5.303.2.1, A5.303.2.3.1, A5.303.2.3.2,

A5.303.2.3.3

Wastewater reduction 5.303.4

Water Use Baseline Table A5.303.2.2

Water Use, Outdoor 4.304, 5.304, A4.304, A5.304

Graywater irrigation system A5.304.8 Low-water consumption irrigation system A4.304.1 Outdoor potable water meters A4.304.3, A5.304.2 Potable water elimination A4.304.2 Previously developed sites A5.304.7 Rainwater or stormwater collection systems A4.304.1 Restoration of areas disturbed by construction A5.304.6 Worksheet Baseline Water Use Chapter 8, (WS-1) 12%, 20% or 25% Reduction Water Use Calculation Table Chapter 8, (WS-2) Building Reuse Chapter 8, (WS-3) Whole Building Life Cycle Assessment 5.409.2, Chapter 8, (WS-4) Product GWP Compliance— Prescriptive Path 5.409.3, Chapter 8, (WS-5) Building Reuse Tier 1 and Tier 2 Chapter 8, (WS-6) Whole Building Life Cycle Assessment A5.409.2, Chapter 8, (WS-7) Product GWP Compliance— Prescriptive Path A5.409.3,
CALGreen § 220.0 High relevance — show source text
220.0 – R –

Rainwater. [BSC-CG & HCD 1] Precipitation on any pub- lic or private parcel that has not entered an offsite storm drain system or channel, a flood control channel, or any other stream channel, and has not previously been put to beneficial use. Rainwater Catchment System. [BSC-CG & HCD 1] A facility designed to capture, retain, and store rainwater flow- ing off a building, parking lot, or any other manmade imper- vious surface for subsequent onsite use. Rainwater catchment system is also known as “Rainwater Harvesting System” or “Rainwater Capture System.” Rainwater Storage Tank. The central component of the rainwater catchment system. Also, known as a cistern or rain barrel.

2025 CALIFORNIA PLUMBING CODE 41

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

DEFINITIONS

Receiving Landscape. [BSC-CG & HCD 1] Includes features such as soil, basins, swales, mulch, and plants.

Receptor. An approved plumbing fixture or device of such material, shape, and capacity as to adequately receive the discharge from indirect waste pipes, so constructed and located as to be readily cleaned.

Reclaimed (Recycled) Water. [BSC-CG, HCD 1 & DWR] Nonpotable water that meets California State Water Resources Control Board statewide uniform criteria for dis- infected tertiary recycled water. Reclaimed (recycled) water is also known as “recycled water” or “reclaimed water”.

Recycled Water Supply System. [DWR] The building supply pipe, the water distribution pipes, and the necessary connecting pipes, fittings, control valves, backflow preven- tion devices, and all appurtenances carrying or supplying reclaimed (recycled) water in or adjacent to the building or within the premises.

Registered Design Professional. An individual who is registered or licensed by the laws of the state to perform such design work in the jurisdiction.

Regulating Equipment. Includes valves and controls used in a plumbing system that is required to be accessible or readily accessible.

Relief Vent. A vent, the primary function of which is to provide circulation of air between drainage and vent systems or to act as an auxiliary vent on a specially designed system.

Remote Outlet. Where used for sizing water piping, it is the furthest outlet dimension, measuring from the meter, either the developed length of the cold-water piping or through the water heater to the furthest outlet on the hot-water piping.

Rim. See Flood-Level Rim.

Riser. A water supply pipe that extends vertically one full story or more to convey water to branches or fixtures.

Roof Drain. A drain installed to receive water collecting on the surface of a roof and to discharge it into a leader, downspout, or conductor.

Roof Washer. A device or method for removal of sediment

and debris from a collection surface by diverting initial rainfall from entry into the cistern(s). Also, known as a first flush device.
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.
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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.

CALGreen § 305.1 Medium relevance — show source text

305.1**Piping is installed to permit future use of a graywater
irrigation system served by the clothes washer or other fixtures.||
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| |A4.305.2 Recycled water piping is installed.||
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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
MATERIAL CONSERVATION AND RESOURCE EFFICIENCY
Foundation Systems
A4.403.1A Frost-protected Shallow Foundation (FPSF) is designed and constructed.						
A4.403.2Cement use in foundation mix design is reduced. Tier 1. Not less than a 20 percent reduction in cement use. **Tier 2.

CALGreen § 504.4.8 Medium relevance — show source text
A5.504.4.8

Product GWP Limits Table 5.409.3

Referenced Organizations and Standards Chapter 6 Renewable Energy A5.211

Site Development 4.106, 5.106, A4,106, A5.106 Bicycle parking and changing rooms 5.106.4, A5.106.4.3, Table A5.106.4.3 Bird friendly building design A5.107 Building orientation Appendix A6.1 (OSHPD), A5.106.9 Designated parking for clean air vehicles A5.106.5.1 Exterior wall shading A5.106.7 Grading and paving 4.106.3, 5.106.10 Heat island effect – cool roof Tables A4.106.5(1) – (4), A5.106.11.2, Table

A5.106.11.2 Heat island effect – hardscape alternatives A5.106.11, A5.106.11.1 Landscape design A4.106.3 Light pollution reduction 5.106.8 Low impact development A5.106.3 Reduce parking capacity A5.106.6 Shade trees 5.106.12, A5.106.11.3 Soil analysis and protection A4.106.2 Storm water management A5.106.2 Water permeable surfaces A4.106.4 Site Preservation A4.104, A5.104 Reduce development footprint and optimize open space A5.104.1 Site Selection A4.103, A5.103 Brownfield, greyfield or infill site development A5.103.2 Community connectivity A4.103.2, A5.103.1

Voluntary Measures 301.1, 306 Voluntary Tiers 304, 305, 306, A4.601, A5.601

Water Resistance and Moisture Management 5.407, 5.505, A4.407, Appendix A6.1 (OSHPD) A5.407 Moisture control 4.505, 5.407.2, 5.505, Appendix A6.1 (OSHPD) A5.407.9, Appendix A6.1 (OSHPD) A5.505.2 Weather protection 5.407.1, A5.407.3

Water Reuse Systems A4.305 Graywater A4.305.1, A5.304.8 Recycled water for landscape irrigation A4.305.3 Recycled water piping A4.305.2 Water Use, Indoor 4.303, 5.303, A4.303, A5.203

Appliances A4.303.3, A5.303.3, Appendix A6.1 (OSHPD) A5.210 Dual plumbing A5.303.5 Fixture flow rates 4.303.1, Table A5.303.2.3.1, 5.303.2.3.1, A4.303 Kitchen faucets and dishwashers

A4.303.1

Meters 4.303.2, 5.303.1 Multiple showerheads serving one shower 4.303.1.3.2, 5.303.3.3.2 Nonwater urinals and waterless toilets
CALGreen § 305.2 Medium relevance — show source text
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.

2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A4-13

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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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A4 RESIDENTIAL VOLUNTARY MEASURES

DIVISION A4.4 – MATERIAL CONSERVATION AND RESOURCE EFFICIENCY

SECTION A4.401—GENERAL (RESERVED)

SECTION A4.402—DEFINITIONS

A4.402.1 Definitions. The following terms are defined in Chapter 2.

ASSEMBLY (ASSEMBLY PRODUCT).

POSTCONSUMER CONTENT.

PRECONSUMER (OR POSTINDUSTRIAL) CONTENT.

PROPORTIONAL RECYCLED CONTENT (PRC M ).

RECYCLED CONTENT (RC).

RECYCLED CONTENT VALUE (RCV).

Assembly products (RCV A ). Materials (RCV M ).

SECTION A4.403—FOUNDATION SYSTEMS

A4.403.1 Frost protected foundation systems. As allowed by local conditions, utilize a Frost-Protected Shallow Foundation (FPSF) in compliance with the California Residential Code (CRC). When an FPSF foundation system is installed, the manual required by Section 4.410.1 shall include instructions to the owner or occupant regarding the necessity for heating the structure as required in Section R403.3 of the California Residential Code.

A4.403.2 Reduction in cement use. As allowed by the enforcing agency, cement used in foundation mix design shall be reduced as follows:

Tier 1. Not less than a 20 percent reduction in cement use.

Tier 2. Not less than a 25 percent reduction in cement use.

Note: Products commonly used to replace cement in concrete mix designs include, but are not limited to:
1. Fly ash.
2. Slag.
3. Silica fume.
4. Rice hull ash.
SECTION A4.404—EFFICIENT FRAMING TECHNIQUES
CEC § 40201 Medium relevance — show source text
PROPORTIONAL RECYCLED CONTENT (PRCM). The amount of recycled content of a material in an assembly as related to the percentage of the material in an assembly product. PRCM is derived by multiplying the percentage of each material in an assembly by the percentage of recycled content in the material.

PSIG. Pounds per square inch, gauge.

RAINWATER. Precipitation on any public or private parcel that has not entered an offsite storm drain system or channel, a flood control channel, or any other stream channel, and has not previously been put to beneficial use.

RAINWATER CATCHMENT SYSTEM. A facility designed to capture, retain and store rainwater flowing off a building, parking lot, or any other manmade impervious surface for subsequent onsite use. Rainwater catchment system is also known as “Rainwater Harvesting System” or “Rainwater Capture System.”

REACTIVE ORGANIC COMPOUND (ROC). Any compound that has the potential, once emitted, to contribute to ozone formation in the troposphere.

RECLAIMED (RECYCLED) WATER. Nonpotable water that meets California State Water Resources Control Board statewide uniform criteria for disinfected tertiary recycled water. Reclaimed (recycled) water is also known as “recycled water” or “reclaimed water.”

RECOVERED ENERGY. [CEC] The energy used in a building that (1) is recovered from space conditioning, service water heating, lighting, or process equipment after the energy has performed its original function; (2) provides space conditioning, service water heating, or lighting; and (3) would otherwise be wasted.

RECOVERED ENERGY, ON-SITE. [CEC] The recovered energy that is captured at the building site.

RECYCLE or RECYCLING. The process of collecting, sorting, cleansing, treating and reconstituting materials that would otherwise become solid waste, and returning them to the economic mainstream in the form of raw material for new, reused or reconstituted products which meet the quality standards necessary to be used in the marketplace. “Recycling” does not include transformation, as defined in Public Resources Code Section 40201.

RECYCLED CONTENT. [BSC-CG, DSA-SS] Refer to International Organization for Standardization ISO 14021—Environmental labels and declarations—Self-declared environmental claims (Type II environmental labeling).

RECYCLED CONTENT (RC). [HCD] The amount of recycled material in an assembly product or material. Refer to International Organization for Standardization ISO 14021– Environmental labels and declarations–Self-declared environmental claims (Type II environmental labeling). RECYCLED CONTENT VALUE (RCV). [BSC-CG, DSA-SS] Material cost multiplied by postconsumer content plus [1] / 2 the preconsumer content, or RCV = $ X (postconsumer content + [1] / 2 preconsumer content).

RECYCLED CONTENT VALUE (RCV). [HCD]

Assembly products (RCVA). Assembly product cost multiplied by the recycled content of the assembly based on all of the postconsumer content and 50 percent of the preconsumer content.

Materials (RCVM). Material cost multiplied by recycled content of the material based on all of the postconsumer content and 50 percent of the preconsumer content.
CALGreen § 303.4 Medium 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.

2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A5-21

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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 § 2-8 Medium relevance — show source text
PRECONSUMER (OR POSTINDUSTRIAL) CONTENT. [HCD] Material diverted from the waste stream during one manufacturing process, including scraps, damaged goods and excess production that is reclaimed and used in another manufacturing process. Excluded is reutilization of materials such as rework, regrind or scrap generated in a process and capable of being reclaimed within the same process that generated those wastes.

PROCESS. [CEC] An activity or treatment that is not related to the space conditioning, lighting, service water heating or ventilating of a building as it relates to human occupancy.

PROCESS SPACE. A space that is thermostatically controlled to maintain a process environment temperature less than 55°F or to maintain a process environment temperature greater than 90°F for the whole space that the system serves, or that is a space with a space-conditioning system designed and controlled to be incapable of operating at temperatures above 55°F or incapable of operating at temperatures below 90°F at design conditions.

2-8 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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DEFINITIONS

PRODUCT-WEIGHTED MIR (PWMIR). The sum of all weighted-MIR for all ingredients in a product subject to this article. The PWMIR is the total product reactivity expressed to hundredths of a gram of ozone formed per gram of product (excluding container and packaging).

Note: PWMIR is calculated according to equations found in CCR, Title 17, Section 94521(a).

PROPORTIONAL RECYCLED CONTENT (PRCM). The amount of recycled content of a material in an assembly as related to the percentage of the material in an assembly product. PRCM is derived by multiplying the percentage of each material in an assembly by the percentage of recycled content in the material.

PSIG. Pounds per square inch, gauge.

RAINWATER. Precipitation on any public or private parcel that has not entered an offsite storm drain system or channel, a flood control channel, or any other stream channel, and has not previously been put to beneficial use.

RAINWATER CATCHMENT SYSTEM. A facility designed to capture, retain and store rainwater flowing off a building, parking lot, or any other manmade impervious surface for subsequent onsite use. Rainwater catchment system is also known as “Rainwater Harvesting System” or “Rainwater Capture System.”

REACTIVE ORGANIC COMPOUND (ROC). Any compound that has the potential, once emitted, to contribute to ozone formation in the troposphere.

RECLAIMED (RECYCLED) WATER. Nonpotable water that meets California State Water Resources Control Board statewide uniform criteria for disinfected tertiary recycled water. Reclaimed (recycled) water is also known as “recycled water” or “reclaimed water.”

RECOVERED ENERGY. [CEC] The energy used in a building that (1) is recovered from space conditioning, service water heating, lighting, or process equipment after the energy has performed its original function; (2) provides space conditioning, service water heating, or lighting; and (3) would otherwise be wasted.

RECOVERED ENERGY, ON-SITE. [CEC] The recovered energy that is captured at the building site.

Frequently asked questions

Can I count gutter/downspout area toward the 65% roof capture requirement?

Yes — the code measures the available roof area used by the system. The catchment must be designed to use rainwater generated by at least 65 percent of that area per § A4.304.1. Design specifics (leaders, gutters, roof washers) follow the California Plumbing Code. file

Does CALGreen force me to stop using potable water for irrigation?

No — § A4.304.2 requires a water‑efficient landscape design that eliminates potable irrigation beyond initial establishment only “as allowed by local ordinance.” Check your local water and planning ordinances before assuming elimination is mandatory.

If recycled water isn’t available now, do I still need to do anything?

Yes — § A4.305.2 requires installing dual piping for future recycled water based on projected availability; if recycled water is not expected, the requirement may not apply. Consult the local water agency/enforcing authority.

What does “install piping to permit graywater use” mean in practice?

It means providing alternative or dedicated piping (roughed‑in lines, valves or stub‑outs) so the clothes washer (and other permitted fixtures) can later be connected to a compliant graywater irrigation system; final design/connection must meet the California Plumbing Code. § A4.305.1. file

Are there labeling or hose‑bibb rules for recycled water?

Yes — the California Plumbing Code restricts hose bibbs on recycled water systems and requires special quick‑couplers, signage and valve access‑door labeling for reclaimed water systems. Follow CPC requirements when installing dual/recycled piping.

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