Septic system requirements in Alabama
What landplan.io applies when it designs a septic system in Alabama: the system types allowed, tank sizes, setbacks and soil loading rates, with what septic products cost there.
Updated
Design a septic system for an address in Alabama
Reviewed landplan.io designs by Alabama's own rules, which our staff reviewed against the state's regulations. Last published 5 October 2026.
Septic systems allowed in Alabama
The system types landplan.io permits in Alabama:
- Elevated Sand Mound System
- Subsurface Pressure Trench System
- Subsurface Trench System
- Infiltrator Advanced Treatment Leachfield
- Infiltrator Advanced Enviro-Septic® (AES)
- Discharging System
Septic tank size in Alabama
The daily design flow of a home: 150 gal/day per bedroom, at least 240 gal/day. The septic tank is sized from that flow:
| Daily design flow | Minimum tank |
|---|---|
| up to 240 gal/day | 1,000 gallons |
| 240 to 360 gal/day | 1,500 gallons |
| 360 to 600 gal/day | 2,000 gallons |
| 600 to 720 gal/day | 2,500 gallons |
| 720 to 840 gal/day | 2,750 gallons |
| 840 to 920 gal/day | 3,000 gallons |
| 920 to 1,040 gal/day | 3,250 gallons |
Septic setbacks in Alabama
| From | To | Distance |
|---|---|---|
| Polygon | Existing Septic Component to be Abandoned | 5 ft |
These are the values the landplan.io design engine applies in Alabama. Confirm a design with the Alabama health department or your county's before you build.
Septic companies, designers and jobs in Alabama
- Septic companies and distributors in Alabama (51)
- Septic designers in Alabama
- Septic design jobs in Alabama
Where the rules come from
The regulations and documents landplan.io's Alabama rules are read from:
- Chapter 420-3-1 - Onsite Sewage Treatment and Disposal (Ala. Admin. Code r. 420-3-1-.01 through .70)
- Rule 420-3-1-T5, Table 5 - Additional Minimum Setback Distances for a Large-Flow OSS (transcribed from the Administrative Code image) (Ala. Admin. Code r. 420-3-1, Table 5)
- Rule 420-3-1-T6, Table 6 - Additional Minimum Setback Distances for an Innovative EDS (transcribed from the Administrative Code image) (Ala. Admin. Code r. 420-3-1, Table 6)
- Rule 420-3-1-T4, Table 4 - Minimum Setback Distances to Components of an OSS (transcribed from the Administrative Code image) (Ala. Admin. Code r. 420-3-1, Table 4)
Septic rules by county in Alabama
- Autauga County
- Baldwin County
- Barbour County
- Bibb County
- Blount County
- Bullock County
- Butler County
- Calhoun County
- Chambers County
- Cherokee County
- Chilton County
- Choctaw County
- Clarke County
- Clay County
- Cleburne County
- Coffee County
- Colbert County
- Conecuh County
- Coosa County
- Covington County
- Crenshaw County
- Cullman County
- Dale County
- Dallas County
- DeKalb County
- Elmore County
- Escambia County
- Etowah County
- Fayette County
- Franklin County
- Geneva County
- Greene County
- Hale County
- Henry County
- Houston County
- Jackson County
- Jefferson County
- Lamar County
- Lauderdale County
- Lawrence County
- Lee County
- Limestone County
- Lowndes County
- Macon County
- Madison County
- Marengo County
- Marion County
- Marshall County
- Mobile County
- Monroe County
- Montgomery County
- Morgan County
- Perry County
- Pickens County
- Pike County
- Randolph County
- Russell County
- Shelby County
- St Clair County
- Sumter County
- Talladega County
- Tallapoosa County
- Tuscaloosa County
- Walker County
- Washington County
- Wilcox County
- Winston County
Questions
What septic systems are allowed in Alabama?
landplan.io permits these system types in Alabama: Elevated Sand Mound System, Subsurface Pressure Trench System, Subsurface Trench System, Infiltrator Advanced Treatment Leachfield, Infiltrator Advanced Enviro-Septic® (AES) and Discharging System.
What size septic tank do I need in Alabama?
landplan.io sizes the septic tank in Alabama from the daily design flow: up to 240 gal/day: 1,000 gallons; 240 to 360 gal/day: 1,500 gallons; 360 to 600 gal/day: 2,000 gallons; larger flows need larger tanks. A home's design flow is 150 gal/day per bedroom, at least 240 gal/day.