Plumbing code requirements

California Plumbing Code: Chapter 15 describes graywater system requirements [PDF] will open to an overview of clothes washer (Laundry to Landscape) graywater systems that don't require a construction permit (Section 1502.1.1 on pages 353 and 354 of the linked PDF, or pages 310 and 311 of the printed version.). Summarized below. Check with your local building or permitting department for additional rules to consider when planning your project. 

Please note, some of the requirements below are already reflected in the rebate program's Rebate Requirements. This list is provided for your reference:

1. If required, notification has been provided to the enforcing agency (relevant Building or Planning Department) regarding the proposed location and installation of a graywater irrigation or disposal system. Building Department Contact Information (subject to change) municipalities in Santa Clara County.
2. The design shall allow the user to direct the flow to the irrigation or disposal field or the building sewer. The direction control of the gray water shall be clearly labeled and readily accessible to the user.
3. The installation, change, alteration, or repair of the system does not include a potable water connection or a pump and does not affect other building, plumbing, electrical, or mechanical components including structural features, egress, fire-life safety, sanitation, potable water supply piping, or accessibility. Note: The pump in a clothes washer shall not be considered part of the gray water system.
4. The gray water shall be contained on the site where it is generated.
5. Gray water shall be directed to and contained within an irrigation or disposal field.
6. Ponding or runoff is prohibited and shall be considered a nuisance.
7. Gray water may be released above the ground surface provided at least two (2) inches (51 mm) of mulch, rock, or soil, or a solid shield covers the release point. Other methods which provide equivalent separation are also acceptable.
8. Gray water systems shall be designed to minimize contact with humans and domestic pets.
9. Water used to wash diapers or similarly soiled or infectious garments shall not be used and shall be diverted to the building sewer.
10. Gray water shall not contain hazardous chemicals derived from activities such as cleaning car parts, washing greasy or oily rags, or disposing of waste solutions from home photo labs or similar hobbyist or home occupational activities.
11. Exemption from construction permit requirements of this code shall not be deemed to grant authorization for any gray water system to be installed in a manner that violates other provisions of this code or any other laws or ordinances of the enforcing agency.
12. An operation and maintenance manual shall be provided to the owner. Directions shall indicate that the manual is to remain with the building throughout the life of the system and upon change of ownership or occupancy.
13. Gray water discharge from a clothes washer system through a standpipe shall be properly trapped.