Septic Systems

When a home using a septic system is being remodeled, additional reviews and approvals are required by the Department of Public Health, Environmental Health Division (EH) to protect public health now and into the future. This review is required to ensure that new construction does not encroach upon the septic system and to ensure that adequate space is available for a replacement dispersal system. 

For more information please visit the Los Angeles County Department of Public Health website. 

Designation of Future Expansion Area

​While a property maintained dispersal system (leach field or seepage pit) can last 30 years or more, eventually it will be replaced. Any expansion or construction requires the homeowner to designate and test a location for a replacement dispersal system also known as a future expansion area. Undeveloped area of a property may fall into one of three categories:

  1.  Well suited allows for installation of a dispersal system meeting all the requirements;
  2. Moderately suited allows for a dispersal system to be installed if septic tank is upgraded to an advanced treatment system or Non-Conventional Insite Water Treatment System (NOWTS);
  3. Unsuitable for installation of a dispersal system
Designating and testing a location for a future dispersal area allows the homeowner to make an informed decision regarding the location of the future dispersal system. If the proposed construction would make the only remaining well suited area of the property unavailable for use, the owner may face increased future costs when installing the replacement dispersal system as the installation of a NOWTS will be required. 

Exceptions to Designating a Future Expansion 


10% Exemption 



A homeowner may expand their home one time up to 10% of the square footage of the footprint of the home if: 
  • The expansion does not include the addition of a bedroom or bedroom equivalent,
  • The expansion does not take up more than 10% of the remaining undeveloped portion of the property,
  • All required distances between the expansion and the existing system are met,
  • The expansion will not prevent future access for construction of the replacement dispersal system,
  • A California Professional Geologist or California Certified Engineering Geologist completes and signs a report indicating that areas are available on the property for the installation of the replacement dispersal system and no unfavorable geological conditions (e.g. bedrock, high ground water) exist. 

Exceptions Continued


Unsuitable Terrain Exception 

Any project being installed in an area that is determined to be unsuitable for installation of a dispersal system will not require the designation and testing of a future expansion area.

Availability of Public Sewer

If the public sewer is located within 200 feet of the property, a permit will not be issued for repairs to the septic system and the owner is required to connect the house to the sewer when the septic system fails. the designation of a location for a future dispersal system is not required since no permit will be issued to construct a future dispersal system. 

Ground Mounted Solar Panels 

Installation of ground mounted solar panels is not considered a permanent improvement, and therefore do not require designation of a future expansion area. If the location is later determined to be well suited for installation of future expansion area, the solar panels may be relocated to another are of the property.

Evaluation of an Existing Septic System 


Existing septic systems are required to be evaluated by a qualified septic contractor under the following conditions:
  • Prior plans are available and indicate the system is older than 15 years;
  • Prior plans are available, but do not match the current floor plan of the house;
  • Prior plans do not exist for the system.
The evaluation is intended to determine if:
  • The septic system is appropriately sized for the existing house and the proposed changes,
  • The changes have been made to the property that effect setbacks requirements,
  • The tank has deteriorated,
  • The dispersal system (leach lines or seepage pit) is functioning properly.
The results of the septic system evaluation must be submitted on the form provided by EH and include plan showing the layout of the septic system. 

After the evaluation, it is recommended that the location of the septic tank and dispersal system be clearly identified with stakes and caution tape to prevent collapse of the tank, seepage pit cap, or crushing of the leach lines from heavy equipment.

For more information, please call the Land Use Program at (626) 430-5380 or visit the Environmental Health website