top of page


Join our mailing list to receive informative email newsletters.

We don't send an email for each blog entry - we don't like spam either!

  • Writer's pictureCommunity

Marin County CA; Mandates Graywater Systems!

We would like to congratulate Marin County for making the move towards requiring Graywater Reuse. Obviously we have been keeping a close eye on this, including detailed discussions with stakeholders.

GRAYWATER REQUIREMENTS FOR MMWD WATER SERVICE (District Ordinance No. 429 effective February 1, 2016)

Your project (residential or commercial) may be subject to MMWD’s graywater ordinance if:

  • It is new construction and requires a new water service from MMWD, or

  • It is already connected to MMWD’s water system but requires an enlarged water service from MMWD (often due to additional water demands such as the installation of a fire sprinkler system).

If your project meets these conditions, then you will be required to have your building plans reviewed for compliance with the new graywater ordinance. Not all projects needing a new water service or an enlarged water service meet the conditions to require graywater. Some of the graywater requirements include:

  • Graywater systems must meet all site and waterway setback requirements.

  • Soil conditions or slope of the site shall not create pooling or allow run-off of the site.

  • The property needs to have the appropriate landscape plantings for graywater to be used.

  • Irrigation areas must be within 50 feet and cannot be uphill from the graywater source.

MMWD is working directly with all planning and building agencies to receive project transmittals during the building application process. Upon receipt of a plan set, MMWD representatives will review the plans for graywater requirements and contact the applicant to discuss details of the project for clarity prior to issuing a “Graywater Sign-Off Form.”

MMWD requires that the applicant bring the Graywater Sign-Off Form to the Engineering Department when applying for a new water service or an application for an increase in the size of the existing water service. Graywater Sign-Off Forms that require the installation of graywater must be signed-off by the building inspector that compliance has been met. For more information on graywater systems, please visit:



This new requirement supports the district’s ongoing efforts to reduce water demand. For more information about the requirement, contact Engineering Services at 415-945-1530.



bottom of page