CALGreen · California Green Building Standards Code (CALGreen)

Where does CALGreen reference graywater and recycled‑water standards or guidance?

Q: Can I just route graywater from the washing machine into my irrigation without permits?

No. CALGreen § A4.305.1 only requires piping provision for future graywater use; the actual design/installation of an on‑site treated graywater system must comply with the California Plumbing Code and local permitting.

Q: Are these requirements mandatory?

The A4 provisions are in Appendix A4 (Residential Voluntary Measures) ; they are voluntary at the state appendix level unless a local jurisdiction adopts them as mandatory. Verify local adoption.

Q: Where are the technical details (labels, backflow, pressure, testing)?

CALGreen defers to the California Plumbing Code for technical requirements (no direct potable connections, air gaps for makeup water, inspection/maintenance schedules, minimum pressures, etc.). Follow CPC provisions when you design/install systems.

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

Yes — § A4.305.1 encourages providing piping for future graywater use, and § A4.305.2 asks for dual piping “based on projected availability.” If the local authority projects future recycled water, dual piping readies the building for conversion.

For a homeowner: CALGreen tells builders to install piping now so your house can use **graywater** later (from things like the clothes washer) and to use **recycled water** for watering landscapes where available. The code sections **§ A4.305.1** and **§ A4.305.3** set the basic expectations and refer all design and safety details to the California Plumbing Code — so provide the piping and consult the CPC and your local utility/health department before turning any nonpotable water system on.

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

CALGreen requires that new residential projects provide piping and/or use provisions so buildings can employ graywater and recycled water for irrigation and other allowed nonpotable uses. The controlling residential voluntary sections are § A4.305.1 (install piping to permit future graywater irrigation) and § A4.305.3 (use of recycled water for landscape irrigation) — see § A4.305 text for the short prescriptions.

Install piping or use recycled water now (or provide piping for it later); systems must be designed and installed in accordance with the California Plumbing Code.

Requirements in detail

Scope and basic wording

§ A4.305.1 — requires alternative plumbing piping to be installed to permit discharge from the clothes washer or other fixtures to be used for an irrigation system (i.e., enable a future graywater irrigation connection). § A4.305.1 is a piping provision (provision for future graywater use), not itself a full system design or treatment standard.
§ A4.305.3 — states recycled water is used for landscape irrigation. The code ties system design and installation to the California Plumbing Code (CPC). § A4.305.3 signals that where recycled water is provided, landscape irrigation should use it.
Both provisions sit in Appendix A4 — Residential Voluntary Measures, so they are voluntary residential measures unless adopted/required locally; see the Appendix heading.

What "follow the Plumbing Code" means

CALGreen defers technical details (treatment, backflow, labeling, cross‑connection control, inspection frequency, pressure requirements) to the California Plumbing Code; the CPC contains specific mandatory safeguards for on‑site treated nonpotable graywater and reclaimed (recycled) water systems (no direct potable connection, makeup water air‑gap, inspection/maintenance frequencies, minimum pressure for some outlets, etc.).

Decision‑relevant table (quick reference)

Decision factor	What the building owner/designer must do	Code reference
Provide for future graywater irrigation from clothes washer or other fixtures	Install alternative plumbing piping (stub‑outs, separate piping runs) so graywater can be routed for irrigation later	§ A4.305.1
Install recycled‑water plumbing now for interior/exterior use	Dual water piping for future recycled water: interior to serve water closets, urinals and floor drains; exterior from point of connection to structure	§ A4.305.2
Use recycled water for landscape irrigation	Where available, recycled water is to be used for landscape irrigation	§ A4.305.3
System design & safety details (cross‑connections, labeling, pressure, testing, maintenance)	Follow the California Plumbing Code for treated graywater/nonpotable/recycled water systems	See California Plumbing Code referenced by § A4.305.x
Nonresidential graywater irrigation (onsite subsurface)	For nonresidential voluntary measures, Appendix A5 specifically directs installation of graywater collection for onsite subsurface irrigation per the CPC	§ A5.304.8

Design/implementation notes

The code language for § A4.305.1 is about installing piping to permit future use (i.e., routing and stub‑outs), not requiring an active graywater treatment system at permit time.
Recycled water piping requirements (dual piping) in § A4.305.2 are tied to projected availability and identify specific interior and exterior locations for dual piping (toilets, urinals, floor drains, and exterior distribution). The design/installation must conform to the CPC.

Exceptions & special cases

Local adoption: Appendix A4 is a voluntary residential appendix. Local jurisdictions may adopt, modify, or require these measures; check local adoption tables or local ordinance. CALGreen’s Appendix flags these as voluntary unless adopted.
Projected availability: § A4.305.2 is explicitly “based on projected availability” — enforceable choice depends on whether recycled water supply is expected to be available. If not expected, the local enforcing agency may not require immediate recycled water piping.
Nonresidential vs residential: Appendix A5 contains nonresidential voluntary measures with explicit graywater irrigation guidance (e.g., § A5.304.8) that reference onsite subsurface irrigation; CALGreen still defers technical details to the CPC.

Common mistakes

Mistake: Treating § A4.305.1 as requiring a functioning graywater treatment system at permit. Reality: it requires piping provisions to permit future graywater use, not full system construction.
Mistake: Assuming recycled/graywater can be cross‑connected to potable supply. The CPC prohibits direct connections and requires air gaps, backflow protection and other controls; do not interconnect without complying with CPC.
Mistake: Ignoring local adoption/availability. Appendix provisions may be voluntary; also recycled water use depends on local supply and utility rules. Check local code adoption and utility availability.

Worked example — single‑family house (numbers)

Scenario: New single‑family home with 3,200 ft² landscaped area; owner wants to allow future graywater irrigation and prepare for recycled water if the city supplies it later.

Graywater piping per § A4.305.1: run an alternative plumbing piping discharge from the clothes washer to an exterior stub‑out located near planting beds. Example: install a 20‑ft dedicated discharge conduit and capped irrigation stub at property edge — this satisfies the “permit future use” requirement. § A4.305.1
Recycled‑water readiness per § A4.305.2: based on projected availability, install dual piping from the point of connection to the structure for exterior irrigation and install interior stub‑outs (e.g., piping runs to toilet rooms) so recycled water could serve water closets later. Example: add an exterior purple sleeve and interior capped purple supply runs to two toilets (future tie‑in locations). § A4.305.2
If the local water district supplies recycled water and the owner converts the landscape irrigation, then the landscape irrigation should use recycled water per § A4.305.3, and the system must be installed per the California Plumbing Code (backflow, labeling, pressure, etc.). Example: 3,200 ft² plant area irrigated with recycled water after conversion; confirm cross‑connection controls and CPC compliance before activation. § A4.305.3

Related provisions (CALGreen)

§ A4.305.2 — Recycled water piping (dual piping locations and CPC requirement).
§ A4.304.2 — Potable water elimination; lists use of recycled water and use of graywater among methods for eliminating potable irrigation.
§ A4.304.3 — Landscape water meters (separate submeters for outdoor potable water when applicable). 5,000 square feet threshold referenced in Appendix A4.
§ A5.304.8 — Nonresidential graywater irrigation system (install graywater collection for onsite subsurface irrigation; see CPC).
§ A4.303.2 — Alternate water sources for nonpotable applications (indoor).
California Plumbing Code — technical requirements for graywater and recycled water systems (cross‑connection control, testing, labeling, pressure, maintenance). The CPC is the authority for design/installation details referenced throughout A4/A5.

Code references

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

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 § 504.4.8 High 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 § 303.5 Medium 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 § 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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concepts or local environmental conditions.||||||| |Item 1|
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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 § 303.3 Medium 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
concepts or local environmental conditions.||||||| |Item 1|
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APPENDIX A4-26 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

CALGreen § 304.8 Medium relevance — show source text

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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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.)

Adopting agency	BSC	BSC- CG	SFM	HCD	Col6	Col7	DSA	Col9	OSHPD	Col11	Col12	Col13	Col14	Col15	BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
Adopting agency	BSC	BSC- CG	SFM	1	2	1/AC	AC	SS	1	1R	2	3	4	5	5	5	5	5	5	5	5	5
Adopt entire CA chapter		X
Adopt entire chapter as amended (amended sections listed below)
Adopt only those sections that are listed below
Chapter/Section

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A5 NONRESIDENTIAL VOLUNTARY MEASURES

DIVISION A5.4 – MATERIAL CONSERVATION AND RESOURCE EFFICIENCY

SECTION A5.401—GENERAL

CALGreen § 14877.3. Medium relevance — show source text
** No permit for an on-site treated nonpotable gray water system shall be issued until complete plumbing plans, with data satisfactory to the Authority Having Jurisdiction, have been submitted and approved. [BSC-CG & HCD 1] Prior to commencing the issuance of permits for indoor gray water systems pursuant to state requirements relating to graywater, a city, county, city and county or other local agency shall seek consultation with the local public health department to ensure that local pub- lic health concerns are addressed in local standards or ordi- nances, or in issuing permits. See California Water Code Section 14877.3.

1506.3 System Changes. No changes or connections shall be made to either the on-site treated nonpotable gray water system or the potable water system within a site containing an on-site treated nonpotable gray water system without approval by the Authority Having Jurisdiction. 1506.4 Connections to Potable or Recycled Water Supply Systems. On-site treated nonpotable gray water systems shall have no direct connection to a potable water supply or recycled water supply system.

Exceptions:

(1) Potable or reclaimed (recycled) water is permitted to be used as makeup water for a non-pressurized storage tank provided the makeup water supply inlet is protected by an air gap in accordance with this code.

(2) A potable water supply may be connected temporarily for the initial cross-connection test of the on-site treated non- potable gray water system as provided in Section 1502.3.2. 1506.5 Water Pressure. On-site treated non-potable gray water systems supplying water to water closets, urinals, and trap primers shall be capable of delivering not less than 15 pounds-force per square inch (psi) (103 kPa) residual pressure at the highest and most remote outlet served. Where the

TABLE 1505.16 MINIMUM RECLAIMED (RECYCLED) WATER SOURCE TESTING, INSPECTION, AND MAINTENANCE FREQUENCY

DESCRIPTION MINIMUM FREQUENCY*

Inspect and clean filters and screens, and replace (where necessary). [Every 3 months.]

Inspect pumps and verify operation. After initial installation and every 12 months thereafter.

Inspect valves and verify operation. After initial installation and every 12 months thereafter.

Inspect pressure tanks and verify operation. After initial installation and every 12 months thereafter.

Clear debris from and inspect storage tanks, locking devices, and verify operation.

After initial installation and every 12 months thereafter.

Inspect caution labels and marking. After initial installation and every 12 months thereafter.

* Note: Frequency is as described in this table, or more frequently as required by manufacturer’s instructions and/or the Authority Having Jurisdiction.

322 2025 CALIFORNIA PLUMBING CODE

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

ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS
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.

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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 § 303.1 Medium relevance — show source text
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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 § 1.12 Medium relevance — show source text
Includes water closets with an effective flush rate of 1.12 gallons or less when tested per ASME A 112.19.2 and ASME A 112.19.14.
2. See Table A5.503.2.2 for additional notes and references.
3. Where complying faucets are unavailable, aerators rated at 0.35 gpm or other means may be used to achieve reduction.
4. Floor-mounted urinals @ 0.5 GPF or wall-mounted urinals @ 0.125 GPF.|

A5.303.2.3.2 Tier 2 – 20-percent savings. A schedule of plumbing fixtures and fixture fittings that will reduce the overall use of potable water within the building by 20 percent shall be provided. A calculation demonstrating a 20-percent reduction in the building “water use baseline” as established in Table A5.303.2.2 shall be provided. A5.303.2.3.3 25-percent savings. A schedule of plumbing fixtures and fixture fittings that will reduce the overall use of potable water within the building by 25 percent shall be provided. A calculation demonstrating a 25-percent reduction in the building “water use baseline” as established in Table A5.303.2.2 shall be provided. A5.303.2.3.4 Nonpotable water systems for indoor use. Utilizing nonpotable water systems (such as captured rainwater, treated graywater and recycled water) intended to supply water closets, urinals and other allowed uses, may be used in the calculations demonstrating the 12-, 20- or 25-percent reduction. The nonpotable water systems shall comply with the current edition of the California Plumbing Code.

A5.303.3 Appliances and fixtures for commercial application. Appliances and fixtures shall meet the following:
1. Clothes washers shall have a maximum Water Factor (WF) that will reduce the use of water by 10 percent below the California Energy Commissions’ WF standards for commercial clothes washers located in Title 20 of the California Code of Regulations.
2. Dishwashers shall meet the following water use standards: a. Residential—ENERGY STAR.
i. Standard Dishwashers – 4.25 gallons per cycle. ii. Compact Dishwashers – 3.5 gallons per cycle. b. Commercial—Shall be in accordance with ENERGY STAR requirements. Refer to Table A5.303.3. 3. Ice makers shall be air cooled.
1. Food steamers shall be connectionless or boilerless – and shall consume no more than 2 gallons of water per pan per hour, including condensate water, for batch type steamers, and no more than 5 gallons of water per pan per hour, including condensate water, for cook to order steamers.
2. The use and installation of water softeners that discharge to the community sewer system may be limited or prohibited by local agencies if certain conditions are met.
3. Combination ovens shall use a maximum of 1.5 gallons of water per hour per pan, including condensate water.
4. Food waste pulping systems shall use no more than 2 gpm of potable water. 7.1. Note: potable water excludes on-site graywater use, such as dishwasher discharge water.
|TABLE A5.303.
CALGreen § 405.3.1.1 Medium relevance — show source text
For the purposes of this section, materials used as components of the structural frame shall not be used to calculate recycled content. The structural frame includes the load bearing structural elements, such as wall studs, plates, sills, columns, beams, girders, joists, rafters and trusses.

Notes:
1. Sample forms which allow user input and automatic calculation are located at https://www.hcd.ca.gov/building- standards/calgreen and may be used to simplify documenting compliance with this section and for calculating recycled content value of materials or assembly products.
2. Sources and recycled content of some recycled materials can be obtained from CalRecycle if not provided by the manufacturer.
A4.405.3.1.1 Total material cost. Total material cost is the total estimated or actual cost of materials and assembly products used in the project. The required total recycled content value for the project (in dollars) shall be determined by Equation A4.41 or Equation A4.4-2.

Total material cost shall be calculated by using one of the methods specified below:
1. Simplified method. To obtain the total cost of the project, multiply the square footage of the residential structure by the square foot valuation established pursuant to the ICC Building Valuation Data (BVD) or other valuation data approved and/or established by the enforcing agency. The total material cost is 45 percent of the total cost of the project. Use Equations A4.4-3A or A4.4-3B to determine total material costs using the simplified method.
(Equation A4.4-3A) Total material costs = Project square footage × square foot valuation × 45 percent

(Equation A4.4-3B) Total estimated or actual cost of project × 45 percent 2. Detailed method. To obtain the total cost of the project, add the estimated and/or actual costs of materials used for the project, including the structure (steel, concrete, wood or masonry); the enclosure (roof, windows, doors and exterior walls); the interior walls, ceilings and finishes (gypsum board, ceiling tiles, etc.). The total estimated and/or actual costs shall not include fees, labor and installation costs, overhead, appliances, equipment, furniture or furnishings.

A4.405.3.1.2 Determination of total recycled content value (RCV). Total RCV may be determined either by dollars or percentage as noted below.
1. Total recycled content value for the project (in dollars). This is the sum of the recycled content value of the materials and/or assemblies considered and shall be determined by Equation A4.4-4. The result of this calculation may be directly compared to Equations A4.4-1 and A4.4-2 to determine compliance with Tier 1 or Tier 2 prerequisites.
(Equation A4.4-4) Total Recycled Content Value (dollars) = (RCV M + RCV A ) 2. Total recycled content value for the project (by percentage). This is expressed as a percentage of the total material cost and shall be determined by Equation A4.4-4 and Equation A4.4-5. The result of this calculation may be directly compared for compliance with Tier 1 (10 percent) or Tier 2 (15 percent) prerequisites.

(Equation A4.4-5) Total Recycled Content Value (percent) = [Total Recycled Content Value (dollars) ÷ Total Material Cost (dollars)] × 100
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

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

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

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

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

Frequently asked questions

Can I just route graywater from the washing machine into my irrigation without permits?

No. CALGreen § A4.305.1 only requires piping provision for future graywater use; the actual design/installation of an on‑site treated graywater system must comply with the California Plumbing Code and local permitting.

Does CALGreen let me use recycled water for toilets?

CALGreen requires installing dual piping for future recycled water to serve water closets and urinals where recycled water is projected to be available (see § A4.305.2). Actual use depends on availability and compliance with the CPC and local utility rules.

Are these requirements mandatory?

The A4 provisions are in Appendix A4 (Residential Voluntary Measures); they are voluntary at the state appendix level unless a local jurisdiction adopts them as mandatory. Verify local adoption.

Where are the technical details (labels, backflow, pressure, testing)?

CALGreen defers to the California Plumbing Code for technical requirements (no direct potable connections, air gaps for makeup water, inspection/maintenance schedules, minimum pressures, etc.). Follow CPC provisions when you design/install systems.

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

Yes — § A4.305.1 encourages providing piping for future graywater use, and § A4.305.2 asks for dual piping “based on projected availability.” If the local authority projects future recycled water, dual piping readies the building for conversion.

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