© 2018 by County of San Luis Obispo Countywide Water Conservation Program.


On April 22, 2008, the Board of Supervisors approved two plumbing retrofit ordinances for the Los Osos and Nipomo Mesa areas. The ordinances address groundwater basin resource constraints by requiring both new and existing development to retrofit older, non-conserving toilets and shower heads with those that are water efficient.  The ordinances went effective May 22, 2008.

The Retrofit to-Build Program (Title 19) requires all new development that uses water from the Los Osos Groundwater Basin (LOGWB) to retrofit older plumbing fixtures in existing homes and businesses to save twice the amount of water the new development will use.  The amount of water savings calculated will be generated to water credits, whereas, the developer can use the retrofit credits to build a new single family home.  A total of 300 retrofit credits are required to build a new single family home. To view the Vacant Lots in Los Osos Frequently Asked Questions sheet, please click here


Effective March 10, 2014, retrofit credits, with the exception of clothes washer retrofits, can no longer come from the Prohibition Zone (see map below). 

For more information on plumbing retrofit programs, please choose one of the following:

To find out if your property is within the Prohibition Zone, visit Land Use View.


Instructions for Land Use View:

  1. Enter the property address at the top right corner in the search engine and click "Enter". 

  2. On the left side panel, click the "+" icon next to "Districts and Boundaries" to expand the list of layers.

  3. Under the "District and Boundaries" header, check the box next to "RWQCB - Los Osos Prohibition Zone".

  4. If your property is located within the red lined boundary, it is in the Prohibition Zone. 

  5. If you’re having trouble, please feel free to contact the Department of Planning and Building