CALGreen · California Green Building Standards Code (CALGreen)
Irrigation, recycled water and landscape/nonpotable requirements
If your nonresidential irrigation is regulated by a local water‑efficient ordinance or **MWELO**, CALGreen **§ A5.305.2** requires that irrigation use **recycled water**; and CALGreen **§ A5.305.1** directs all nonpotable systems to be designed and installed in accordance with the **California Plumbing Code** (which contains the technical rules for piping, backflow prevention, purple identification, metering and allowed uses). Confirm recycled‑water availability with the purveyor, follow the Plumbing Code details (e.g., § 1505.1 and Appendix L), and document compliance on the plans.
Last reviewed: July 6, 2026
What the code requires
- In plain English: Nonpotable water systems (for indoor or outdoor uses) must comply with the California Plumbing Code, and where an irrigation system is regulated by a local water‑efficient landscape ordinance or the Model Water Efficient Landscape Ordinance (MWELO) it must use recycled water. These directives are set out in § A5.305.1 and § A5.305.2 of CALGreen.
If your project’s irrigation is covered by a local water‑efficient landscape ordinance or by MWELO, plan to use recycled water for irrigation and follow the California Plumbing Code for how to plumb, protect, mark and operate that system.
Requirements in detail
Core requirements (the two controlling sections)
- § A5.305.1 — Nonpotable water systems for indoor and outdoor use must comply with the current California Plumbing Code. This means design, materials, labeling, backflow protection, separation and other plumbing specifics are governed by the Plumbing Code, not by CALGreen text alone.
- § A5.305.2 — Irrigation systems that are regulated by a local water‑efficient landscape ordinance or MWELO shall use recycled water (i.e., reclaimed/recycled water supplied or permitted by the purveyor).
Key implementation items referenced from the California Plumbing Code (required by § A5.305.1)
The Plumbing Code contains the operational details you must follow when implementing nonpotable/recycled water use:
- Required allowed uses, and plumbing scope for recycled water systems are defined in § 1505.1 (recycled water supply systems) — includes aboveground/subsurface irrigation among allowed uses.
- Identification and segregation requirements (purple pipe, signage, hose bibb markings) and master‑valve/zone marking are in the Plumbing Code (e.g., Appendix L irrigation provisions such as identification and master valve rules).
- Backflow protection and cross‑connection control are required for potable vs. reclaimed supplies; the Plumbing Code references State cross‑connection policy and Title 22/23 applicability.
- Where alternate water sources are available by existing treatment/distribution, the Plumbing Code requires the irrigation system be designed to use a minimum of 75% alternative water for annual irrigation demand before potable makeup is used (where approved and capacity exists).
- Metering and dedicated meter rules (landscape metering thresholds and dedicated‑meter exceptions) are in the Plumbing Code (Table L 407.1 and related text).
Decision‑relevant table
| Decision question | What to do | Key values / thresholds | Code reference |
|---|---|---|---|
| Is the irrigation system regulated by local ordinance or MWELO? | Use recycled water for irrigation | Regulation = yes → recycled water required | § A5.305.2 |
| Is this a nonpotable water system (indoor or outdoor)? | Design/installation must follow the California Plumbing Code | All nonpotable systems — indoor & outdoor | § A5.305.1 |
| Is an alternate water source already available via treatment/storage/distribution? | Design to use at least 75% of alternate source before potable makeup (where approved and capacity exists) | 75% of annual irrigation demand | Plumbing Code Appendix L (alternate water source use) |
| Must irrigation piping/fixtures be identified and protected from cross‑connection? | Yes — purple pipe, signage, backflow protection and other requirements apply | Purple identification; posted warning at hose bibbs: “CAUTION: NONPOTABLE WATER. DO NOT DRINK” | Plumbing Code Appendix L; § 1505.x (recycled water rules) |
| Is dual piping or stub‑out required for future recycled water use? | Install dual piping or stub‑outs where future recycled water use is projected/anticipated (see residential Appendix language and Plumbing Code) | Install exterior piping from point of connection to structure where projected | A4.305.2 (residential elective) and Plumbing Code § 1505.x |
(Notes: CALGreen § A5.305.1/A5.305.2 set the policy; the Plumbing Code supplies the technical how‑to. Use both when documenting plans.)
Exceptions & special cases
- CALGreen § A5.305.2 gives the rule that regulated irrigation systems “shall use recycled water,” but it does not itself list availability exceptions — the practical availability, permitting and acceptable uses are governed by the California Plumbing Code and the recycled‑water purveyor’s permit. Consult the Plumbing Code sections on recycled water supply (e.g., § 1505.1) for allowed uses and purveyor permit controls.
- Where a pre‑existing treatment / storage / distribution network exists and is approved, the Plumbing Code requires design to use at least 75% alternative water before potable makeup is used (this is a capacity/availability condition). That is a practical special case when recycled/alternate sources are present.
- Some landscape or plant choices affect irrigation method allowances (e.g., limits on in‑ground irrigation vs. plant choices and vegetative roofs); see Appendix L landscape limitations and vegetative roof rules in the Plumbing Code. These affect whether potable or recycled water may be used for certain features.
- CALGreen Appendix A5 is a set of nonresidential voluntary measures; some project types/permit authorities may apply different mandatory local rules. Confirm whether your project is receiving Appendix A5 voluntary compliance or is subject to mandatory local code.
Common mistakes
- Assuming CALGreen § A5.305.2 alone tells you how to install recycled water systems — it does not: § A5.305.1 directs you to the California Plumbing Code for all installation, labeling and cross‑connection controls. Many designers stop at A5.305.2 and omit the Plumbing Code requirements.
- Failing to check recycled water availability with the local purveyor. CALGreen requires use when regulated by ordinance or MWELO, but practical implementation depends on purveyor permits, service connections and allowed uses in Title 22/23.
- Not using purple identification and proper signage for nonpotable irrigation lines and hose bibbs — a frequent inspection failure. The Plumbing Code requires color coding, labeling and posted warnings on hose bibbs supplied from irrigation systems.
- Omitting backflow protection and cross‑connection controls between potable and recycled systems. The Plumbing Code and State cross‑connection rules apply.
- Treating graywater and recycled (reclaimed) water as interchangeable without checking permitted uses — both are alternate sources but have different code provisions and treatment/permit requirements. See CALGreen sections on graywater (A5.304.8 / A4.305.1) and the Plumbing Code for details.
Worked example — office landscape (numbers)
Scenario: New nonresidential office with 6,000 ft² irrigated landscape. The site is in a city that enforces MWELO.
- Trigger: Because the irrigation is regulated by MWELO, § A5.305.2 requires the irrigation system to use recycled water. Begin coordination with the recycled‑water purveyor and permitting authority.
- Confirm permitted uses and supply: Consult the purveyor and Plumbing Code § 1505.1 for allowed reclaimed‑water uses (subsurface/aboveground irrigation are included). If the purveyor can supply reclaimed water to the site, you must design for it.
- Design requirements from the Plumbing Code:
- Provide required backflow prevention and cross‑connection controls per recycled water rules.
- Use purple piping/valves and labels, and post the required warning at any hose bibb (“CAUTION: NONPOTABLE WATER. DO NOT DRINK”).
- If the purveyor capacity is available and approved, design to deliver ≥75% of annual irrigation demand from the alternative (recycled) source before potable makeup (Plumbing Code Appendix L requirement where applicable). That means sizing storage or controls so recycled water provides ~75% of irrigation use annually.
- For metering: because landscape irrigation areas with in‑ground systems above certain square foot thresholds require dedicated meters (see Plumbing Code metering rules), check Table L 407.1 and install a dedicated meter or submeter if required. For example, Table L 407.1 flags landscape irrigation when total accumulated landscape area with in‑ground irrigation exceeds 2,500 ft² as metric for metering requirements.
- Documentation and plan notes: On permit drawings note compliance with § A5.305.2 and reference the Plumbing Code sections used for recycled‑water materials, labeling and backflow protection. Use the CALGreen compliance template as needed to document Basis of Design for water reuse.
Related provisions (CALGreen)
- § A5.303.5 — Dual plumbing for potable and recycled water for toilet flushing when recycled water is available (nonresidential elective).
- § A5.304.8 — Install a graywater collection system for onsite subsurface irrigation (references the Plumbing Code).
- § A4.305.2 — (Residential Appendix) Install dual recycled water piping for future use where projected (interior for toilet/urinal floor drains; exterior piping from point of connection).
- Plumbing Code § 1505.1 — Recycled water supply systems: scope, allowed uses, and coordination with purveyors (required by § A5.305.1).
- Plumbing Code Appendix L (L 411.x) — Landscape irrigation specifics: alternate water use, identification (purple), master valve, irrigation design limits and metering.
Code references
Grounded in the retrieved California Green Building Standards Code (CALGreen) — click a citation to read the verbatim passage:
CALGreen § 411.3 High relevance — show source text
Exceptions: (1) Where average annual rainfall is less than 12 inches (305 mm) and in landscape areas where the plant materials have an annual ETc of not exceeding 15 inches (381 mm), an in-ground irrigation system shall be allowed. (2) Where neither potable or reclaimed (recycled) water is used in the irrigation system, an in-ground irrigation system shall be allowed in 100 percent of the landscaped area and vegetative roofs. L 411.3 Vegetative Roofs and Walls. Irrigation systems using potable water for vegetative roofs and walls are prohibited.
L 411.4 Maximum Velocity. Velocity of water flow shall not exceed 5 feet per second (1.5 m/s) for thermoplastic irrigation pipes. Velocity of water flow shall not exceed 7.5 feet per second (2.3 m/s) for metal irrigation pipes.
L 411.5 Backflow Protection. Potable water and reclaimed water supplies to landscape irrigation systems shall be protected from backflow in accordance with this code and the Authority Having Jurisdiction.
L 411.6 Use of Alternate Water Sources for Land- scape Irrigation. Where available by pre-existing treatment, storage, or distribution network, and where approved by the Authority Having Jurisdiction, alternative water source(s) shall be utilized for landscape irrigation. Where adequate capacity and volumes of pre-existing alternative water sources are available, the irrigation system shall be designed to use a minimum of 75 percent of alternative water for the annual irrigation demand before supplemental potable water is used. Exception: Plants grown for food production for direct human consumption. L 411.6.1 Master Valve. Where continuously pressurized alternate water sources supply an existing irrigation system, a master valve shall be installed at the point where the alternate water sources supply piping connects to the existing irrigation system downstream of the backflow preventer where required.
L 411.6.2 Identification. Where alternate water sources supply an existing irrigation system, the existing sprinkler heads, valve boxes, the continuously pressurized line supplying the irrigation master valve, or any other components required by the Authority Having Jurisdiction, shall be colored purple. The piping supplying the irrigation master valve shall be identified in accordance with Chapter 15 of this code. L 411.6.2.1 Additional Zones. Newly installed zones shall have purple pipe.
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APPENDIX L
L 411.10 Mulched Planting Areas. Only low flow emitters with flow rates not to exceed 6.3 gallons (24 L) per hour are allowed to be installed in mulched planting areas with vegetation taller than 12 inches (305 mm). L 411.11 System Performance Requirements. The landscape irrigation system shall be designed and installed to:
(1) Prevent irrigation water from runoff out of the irrigation
zone.
(2) Prevent water in the supply line drainage from draining out between irrigation events.
(3) Not allow irrigation water to be applied onto or enter nontargeted areas including adjacent property and vegetation areas, adjacent hydrozones not requiring the irrigation water to meet its irrigation demand, non-vegetative areas, impermeable surfaces, roadways, and structures.
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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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 § 304.8 High 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-
CGSFM HCD Col6 Col7 DSA Col9 OSHPD Col11 Col12 Col13 Col14 Col15 BSCC DPH AGR DWR CEC CA SL SLC Adopting agency BSC BSC-
CGSFM 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 belowChapter/Section 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A5-23
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A5 NONRESIDENTIAL VOLUNTARY MEASURES
DIVISION A5.4 – MATERIAL CONSERVATION AND RESOURCE EFFICIENCY
SECTION A5.401—GENERAL
CALGreen § 406.0 High relevance — show source text
L 406.0 Fountains and Other Water Features.
L 406.1 Use of Alternate Water Source for Special Water Features. Special water features such as ponds and water fountains shall be provided with reclaimed (recycled) water, rainwater, or on-site treated nonpotable water where the source and capacity are available on the premises and approved by the Authority Having Jurisdiction.
L 407.0 Meters.
L 407.1 Required. A water meter shall be required for each building site connected to a public water system, including municipally supplied reclaimed (recycled) water. In other than single-family houses, a dedicated meter shall be installed in accordance with Table L 407.1.
L 407.2 Approval. Dedicated meters, other than water utility meters shall be approved by the Authority Having Jurisdiction for the intended use.
L 407.3 Remote Data Transfer Requirements. Where more than 10 non-utility-owned water meters are located at a building site, the meters shall include remote data transfer capability to collect and analyze the data at a single location.
L 407.4 Access. Meters and submeters shall be accessible.
L 408.0 Condensate Recovery. L 408.1 General. Condensate is permitted to be used as onsite treated nonpotable water when collected, stored, and treated in accordance with Section 1506.0.
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APPENDIX L
TABLE L 407.1
DEDICATED WATER METERING REQUIREMENTS
APPLICATION REQUIREMENTS Cooling Towers The makeup water supply to cooling towers, evaporative condensers, and fluid coolers. Cooling
towers sharing a common basin can be grouped together using one meter.Evaporative Coolers The makeup water supply to an evaporative cooler having an air flow exceeding 30 000 cubic feet
per minute (ft3/min).Fluid Coolers and Chillers – Open
SystemsThe makeup water supply on water-cooled fluid coolers and chillers not utilizing closed- loop recir-
culation.Hydronic Cooling Systems – Closed
LoopSystems with 50 ton or greater of cooling capacity and where a make-up water supply is connected. Hydronic Heating Systems The makeup water supply to one or more boilers collectively exceeding 1 000 000 British thermal
units per hour (Btu/h).Industrial Processes The water supply to an industrial water-using process where the average consumption exceeds
1000 gallons per day (gal/d). Like equipment sharing one common water supply can be grouped
together using one meter.
Exception: Processes using untreated water where the water is directly returned to the original
source after use.Landscape Irrigation Landscape irrigation water where either of the following conditions exist:
(1)
Total accumulated landscape area with in-ground irrigation system exceeds 2500 square feet
(ft2), or
(2)
Total accumulated landscape area using an automatic irrigation controller exceeds 1500 square
feet (ft2)
Exception: Where the water purveyor provides a separate water supply meter that serves only the
irrigation system, an additional dedicated meter is not required.CALGreen § 410.2 High relevance — show source text
L 410.2 Water Softener Limitations. In residential buildings, where the supplied potable water hardness is equal to or less than 8 grains per gallon (gr/gal) (137 mg/L) measured as total calcium carbonate equivalents, water softening equipment that discharges water into the wastewater system during the service cycle shall not be allowed, except as required for medical purposes.
L 410.3 Point-of-Use Reverse Osmosis Water Treat- ment Systems. Reverse osmosis water treatment systems shall be equipped with automatic shutoff valves to prevent discharge when there is no call for producing treated water. Reverse osmosis water treatment systems shall comply with NSF/ANSI 58 and ASSE 1086.
L 410.4 Drinking Water Treatment Systems. Drinking water treatment systems shall be listed to WQA/ASPE/ANSI S-803.
L 411.0 Landscape Irrigation Systems. L 411.1 General. Where landscape irrigation systems are installed, they shall be in accordance with Section L 411.1.1 through Section L 411.17. L 411.1.1 Irrigation Design and Installation. The Authority Having Jurisdiction shall have the authority to require landscape irrigation contractors, installers, or designers to demonstrate competency. The system shall be designed and record drawings showing changes during installation shall be made available for the owner and for any required inspections. Where required by the Authority
Having Jurisdiction, the contractor, installer, or designer shall be licensed, certified, or both to perform such work. L 411.2 Plant and Irrigation System Limitations. Nuisance, invasive and noxious plants as defined by the Authority Having Jurisdiction shall not be used in the landscape. Plants not requiring supplement irrigation and not principally used as an athletic field or public recreation shall be used in no less than 60 percent of the landscape that is not principally used as an athletic field or public recreation. Inground irrigation system shall not be installed in more than 40 percent of the landscaped area.
Exceptions: (1) Where average annual rainfall is less than 12 inches (305 mm) and in landscape areas where the plant materials have an annual ETc of not exceeding 15 inches (381 mm), an in-ground irrigation system shall be allowed. (2) Where neither potable or reclaimed (recycled) water is used in the irrigation system, an in-ground irrigation system shall be allowed in 100 percent of the landscaped area and vegetative roofs. L 411.3 Vegetative Roofs and Walls. Irrigation systems using potable water for vegetative roofs and walls are prohibited.
L 411.4 Maximum Velocity. Velocity of water flow shall not exceed 5 feet per second (1.5 m/s) for thermoplastic irrigation pipes. Velocity of water flow shall not exceed 7.5 feet per second (2.3 m/s) for metal irrigation pipes.
L 411.5 Backflow Protection. Potable water and reclaimed water supplies to landscape irrigation systems shall be protected from backflow in accordance with this code and the Authority Having Jurisdiction.
L 411.6 Use of Alternate Water Sources for Land- scape Irrigation. Where available by pre-existing treatment, storage, or distribution network, and where approved by the Authority Having Jurisdiction, alternative water source(s) shall be utilized for landscape irrigation.
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:
- Use of captured rainwater.
- Use of recycled water.
- Water treated for irrigation purposes and conveyed by a water district or public entity.
- Use of graywater.
- 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:
- Interior piping for the use of recycled water is installed to serve all water closets, urinals and floor drains.
- 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 § 1504.9 Medium relevance — show source text
1504.9 Other Collection and Distribution Systems. Other collection and distribution systems shall be approved by the local Authority Having Jurisdiction, as allowed by Section 301.3 of this code.
1504.9.1 Future Connections. Gray water stub-out plumbing may be allowed for future connection prior to the installation of irrigation lines and landscaping. Stub- out shall be permanently marked “CAUTION: NON- POTABLE GRAY WATER, DO NOT DRINK.”
1504.10 Testing. Building drains and vents for gray water systems shall be tested in accordance with this code. Surge tanks shall be filled with water to the overflow line prior to and during the inspection. Seams and joints shall be left exposed, and the tank shall remain watertight. A flow test shall be performed through the system to the point of gray water discharge. Lines and components shall be watertight up to the point of the irrigation perforated and drip lines. 1504.11 Maintenance. Gray water systems and components shall be maintained in accordance with Section 1501.5.
1505.0 Recycled Water Supply Systems in Buildings . 1505.1 General. The provisions of Section 1505.0 through Section 1505.16 shall apply to safely plumb buildings with both potable and recycled water supply systems. Unless otherwise specified in this code, the general provisions applying to alter- nate water systems pursuant to Section 1501.0 through Section 1501.10 and Section 1502.4 through Section 1502.6 shall apply to recycled water supply systems. The provisions in this section encompass the installation, construction, alteration, and repair of recycled water supply systems that are within or a part of a building, including a landscape irrigation system that connects to plumbing that is within or a part of a building, and receive reclaimed (recycled) water provided by a water/wastewater util- ity. When dealing with recycled water supply systems, the Authority Having Jurisdiction and Enforcing Agency may include the recycled water purveyor or potable water purveyor in accordance with their respective statutory authority and responsibility as provided on their respective permits for sup- plying water. Plumbing systems using reclaimed (recycled) water that do not enter the interior of a building plumbed with potable water are not encompassed by this section. All reclaimed (recycled) water use, covered and not covered by this code, is subject to applicable provisions of the State Water Resources Control Board’s Cross-Connection Control Policy Handbook and the California Code of Regulations: Title 22 and Title 23 .
1505.1.1 Allowed Uses. Allowed uses shall include water closets, urinals, trap primers for floor drains and floor sinks, aboveground and subsurface irrigation, industrial or commercial cooling or air conditioning and other uses as generally allowed in the California Code of Regulations, Title 22, Division 4, Chapter 3 and specifi- cally allowed in the permit for the facility producing or supplying the reclaimed (recycled) water issued by the State Water Resources Control Board or Regional Water Quality Control Board .
CALGreen § 301.1 Medium 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 § 303.1 Medium 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
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
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:
- Use of captured rainwater.
- Use of recycled water.
- Water treated for irrigation purposes and conveyed by a water district or public entity.
- Use of graywater.
- 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 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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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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| |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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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 MEASURESCol3 Col4 VERIFICATIONS
ENFORCING AGENCY TO SPECIFY
VERIFICATION METHODCol6 Col7 FEATURE OR MEASURE Mandatory Prerequisites and electives1 Prerequisites and electives1 Enforcing
Agency
AllInstaller or
Designer
AllThird
party
AllFEATURE 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 § 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:
- Interior piping for the use of recycled water is installed to serve all water closets, urinals and floor drains.
- 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:
Fly ash.
Slag.
Silica fume.
Rice hull ash.
SECTION A4.404—EFFICIENT FRAMING TECHNIQUES
Frequently asked questions
Who decides whether MWELO or a local ordinance applies to my irrigation?
Local planning/water authorities determine applicability. If your project falls under a local water‑efficient landscape ordinance or is in a jurisdiction that enforces MWELO, § A5.305.2 requires recycled water for regulated irrigation; check with the local permitting agency and the recycled‑water purveyor.
If recycled water isn’t available from the purveyor, am I still required to use it?
CALGreen requires use where irrigation is regulated by local ordinance or MWELO, but practical implementation depends on purveyor availability and permits. The Plumbing Code covers permitted uses and purveyor requirements — coordinate with the purveyor and AHJ to document availability and approved alternatives.
Do I have to install purple pipe and special signage?
Yes. The Plumbing Code requires color identification (purple) for alternate water supply lines and specified signage (e.g., “CAUTION: NONPOTABLE WATER. DO NOT DRINK”) at hose bibbs and outlets when nonpotable water is used. § A5.305.1 directs you to the Plumbing Code for these details.
Is graywater treated the same as recycled (reclaimed) water under CALGreen?
Not automatically. Graywater and recycled (reclaimed) water are both alternate sources but are addressed in different CALGreen/Plumbing Code sections (e.g., A5.304.8 for graywater collection; Plumbing Code/Title 22 for reclaimed water). Verify permitted uses and treatment requirements for each source.
Do CALGreen §§ A5.305.1–A5.305.2 apply to residential projects?
Appendix A5 is a nonresidential voluntary appendix. Residential Appendix provisions (A4) contain parallel items (for example A4.305.2 and A4.305.3). Always confirm which appendix or mandatory chapter applies to your project.
More in California Green Building Standards Code (CALGreen)
- Administration (Chapter 1)
- Nonresidential Voluntary Measures (Appendix A5 — divisions A5.1–A5.6, electives & verification)
- Residential Mandatory Measures — Planning & Design; Energy; Water; Materials; Environmental Quality (Chapter 4)
- Definitions (Chapter 2)
- Voluntary Standards for Health Facilities (Appendix A6 / OSHPD guidance)
- Green Building – scope, mixed occupancies, phased projects (Chapter 3)
- Residential Voluntary Measures (Appendix A4 — divisions A4.1–A4.6, tiers & model ordinance)
- Nonresidential Mandatory Measures — Planning & Design; Energy; Water; Materials; Environmental Quality (Chapter 5)
- Compliance verification, construction documents & checklists (Section 102, Chapter 7, Appendix checklists)
- Referenced Organizations and Standards (Chapter 6)
- Voluntary Tiers and CALGreen Tier 1 / Tier 2 (performance tiers, thresholds)
- Installer and Special Inspector Qualifications (Chapter 7)
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Indoor potable water reduction targets and graywater irrigation systems
Recycled content, construction & demolition waste reduction and life‑cycle assessment options
Efficient framing (wood & steel) and advanced framing techniques
Water Efficiency & Material Conservation (Divisions A5.3–A5.4)
California Green Building Standards Code (CALGreen)