Sewer Lateral Connections and Septic System Decommissioning

Summary: On-lot lateral connections are the responsibility of each property owner.  In general, the connection process includes:

  1. Work with contractors to obtain input and price quotes on the work to be done. 
  2. Determine the best path for your new lateral from the house to the point of connection at the property line. 
  3. Decide if reuse of the septic system to improve water resources works on your property. 
  4. Choose and hire a contractor to complete the work. Seek recommendations from friends or neighbors who have already completed their connection.
  5. The contractor will obtain the necessary building permits and connect the new sewer lateral.
  6. After the lateral is connected, the contractor will have the septic tank pumped out and complete the septic system abandonment or conversion for reuse.

The median cost for the on-lot work is estimated to be about $3,000.  Homes with more complicated situations will have additional costs.  It is recommended that property owners seek recommendations from friends and neighbors who have already completed their connections and request quotes from multiple contractors in order to get a fair price for the work.

Sewer Lateral Connection Schedule: Phase 1 of the sewer lateral connections of individual properties began on March 28, 2016 when the water recycling facility was ready to accept wastewater. 

  • Phase 1 is from March 28, 2016 through September 24, 2016.
  • Phase 2 is from June 20, 2016 through December 17, 2016.
  • Phase 3 is from September 19, 2016 through March 18, 2017.

See the Sewer Lateral Connection Phasing Schedule to identify which phase your property is located in.  Notices were mailed to property owners several weeks before their phase began.  The notices specified the dates on which sewer lateral connections may begin and that connections are required to be done within 180 days. 

Septic System Decommissioning Planning: Property owners have options for decommission their septic systems by either abandoning the septic system in place or repurposing it for a number of sustainable uses which benefit water resources, such as capturing rain water run-off and returning it to the groundwater supply.  The septic tanks may be abandoned in place, which includes having the tank pumped out then filling it with sand, gravel or concrete slurry.  The Septic System Decommissioning and Reuse Plan provides guidance for property owners in planning for a range of septic system repurposing solutions.  Rain water capture and infiltration to groundwater will be a comparable cost to abandoning in-place, while sustainably benefiting local water resources.  Reusing septic tanks to increase your water supply for irrigation or toilet flushing are also discussed.

For more information about converting a septic tank to capture rain water, review this video (the link takes you to the YouTube website) of the process being completed by contractors in Los Osos.  Note: Many contractors are available to provide this service and this video is not an endorsement of any specific contractor(s).

Sewer Lateral Installation Information:  All lateral installation and septic system decommissioning work must comply with the building permit issued and the currently adopted California Plumbing Code. Septic tanks must also be pumped by a licensed septic pumping contractor prior to decommissioning by abandoning in place or repurposing.  Septage may not be discharged to the sewer lateral or collection system.  Review the Sewer Lateral Installation handout for general requirements on sewer lateral materials, pipeline minimum slope, clean-out location, back flow devices, and the inspection process.

Contracting for the Lateral Connection Work: Most property owners will hire contractors to complete the work and should use the licensed companies on the Contractor Interest List.  Using contractors from this list is necessary for compliance with the County’s environmental permits for the project.  Any licensed contractor interested in the work may contact the County to schedule a short training and be added to the list.  Obtaining quotes from multiple contractors is recommended in order to get a fair price for the work. The Contractor State License Board (CSLB) protects consumers and has information on how to select a licensed, qualified contractor, check the status of a contractor license, negotiate a clear contract, prevent disputes and mechanics liens, and resolving contractor disputes.  Please refer to the CSLB's website.

Property owners may also complete the work themselves as “owner-builders”.  They must obtain the proper building permits and follow the California Plumbing Code. There are a number of issues to consider before beginning a construction job as an "owner-builder".  For more information on some of the legal obligations and risks, please refer to the CSLB's website.

Sewer Lateral and Septic Tank Locations: Use this interactive GIS map to find the approximate location of the septic tank and sewer stub-out on most properties in Los Osos.  Zoom to your property location; or enter a property address or Assessor's Parcel Number in the search bar at the top-right of the map and zoom to the yellow dot.  Septic tank locations are approximate and not available for every property. You can also turn on the "Connection Plan" layer to see the boundaries for each of the 3 connection phases.

Shallow Groundwater: Septic tanks that have been repurposed for water supply options may be empty at certain times.  If the empty tanks are in shallow groundwater, there is a risk that they could float and be pushed out of the ground by the water pressure.  This depth to groundwater map is provided for planning purposes to identify whether properties are over shallow groundwater.  A design professional or some contractors can determine whether this is a risk and recommend measures to address it.

Properties which require Environmental Monitoring: The properties shown in yellow on this map contain sensitive environmental resources.  These properties will require environmental monitoring, which will be provided by the County at no cost to the property owner.  The building permits for these properties must be issued as "over-the-counter permits" in order to ensure that the monitoring is coordinated according to the requirements of the project's environmental permits.

Verification of Compliance with CA Retrofit Laws:  State law requires that all homes have smoke detectors and carbon monoxide alarms installed in the dwelling.  State law and the project's environmental permits also require low-flow plumbing fixtures as a condition of connecting properties to the project.  The self-verification form must be signed by the property owner as a condition of completing the building permit process.  Water conservation program rebates are available to cover costs of the plumbing fixture retrofits. 

Related Services

Los Osos Sewer Lateral and Septic Tank Locations

Related Forms & Documents


Contact Public Works via web form, email, or call us at (805) 781-5252.