Summary of Specific Requirements For Gravity Systems
for Single Family Dwellings*
The following is in addition to the items listed on the FAQ page for Gravity System Requirements.
- Vertical Separation: 5' to Water Table, 18" to Rapid Soil
- Trench Sidewall-to-Sidewall Separation: 8'
- Trench Length: 10' to 125'
- Bottom Width: 24" Min.
- Trench Depth: 18" to 36"- Equal or Loop Distribution (<4% slope) 24" to 36" - Serial Distribution Systems (>4% slope)
- Minimum of 2" of gravel over drain lateral, and 6" under, with 6" backfill (12" backfill for serial distribution systems).
- Maximum drop of 1" in 100' for drain lateral.
- Field sizes should be based on 300 gpd for 2 bdrm and 75 gpd for each additional bdrm. Minimum field total length based on soil depth and type. See Tables 4 & 5 in the Lake County Rules:
- Minimum septic tank capacity is 940 gal.; 1200 gal. for 3-4 bedrooms; 1500 gal. for 4 or more bedrooms. An effluent filter is required.
Hidden Valley Lake
Cities and towns (requirements may differ)
Lake County Setback Requirements
For a graphical representation of Lake County setback requirements:
*The information on this page is a summary for quick reference only and may not represent the latest standards. For complete and up-to-date information, see each counties official website.
Links to Lake County Website
For County home page:
For County's Rules for
On-Site Sewage Disposal: