Septic system requirements in Delaware
What landplan.io applies when it designs a septic system in Delaware: 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 Delaware
Reviewed landplan.io designs by Delaware's own rules, which our staff reviewed against the state's regulations. Last published 5 October 2026.
Septic systems allowed in Delaware
The system types landplan.io permits in Delaware:
- Elevated Sand Mound System
- Low Pressure Pipe System
- Conventional Trench System
- Subsurface Micro Irrigation
- Capping Fill Gravity
- Capping Fill Low Pressure Pipe
- Spray Irrigation System
- Infiltrator Advanced Treatment Leachfield (ATL)
- Infiltrator Advanced Enviro-Septic® (AES)
- Discharging System
Septic tank size in Delaware
The daily design flow of a home: 120 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 Delaware
| From | To | Distance |
|---|---|---|
| Polygon | Existing Septic Component to be Abandoned | 5 ft |
These are the values the landplan.io design engine applies in Delaware. Confirm a design with the Delaware health department or your county's before you build.
Parcel data in Delaware
landplan.io has parcel boundaries for 3 of Delaware's 3 counties: the counties where 100% of the state's people live. Type an address there and the design starts from the parcel.
Septic companies, designers and jobs in Delaware
- Septic companies and distributors in Delaware (1)
- Septic designers in Delaware
- Septic design jobs in Delaware
Where the rules come from
The regulations and documents landplan.io's Delaware rules are read from:
- Regulations Governing the Design, Installation and Operation of On-Site Wastewater Treatment and Disposal Systems (7 Del. Admin. Code 7101)
- 7101 Regulations Governing the Design, Installation and Operation of On-Site Wastewater Treatment and Disposal Systems, with Exhibits A-NN (Exhibit C, Minimum Isolation Distances, p.173-174) (7 Del. Admin. Code 7101, Exhibit C)
Septic rules by county in Delaware
Questions
What septic systems are allowed in Delaware?
landplan.io permits these system types in Delaware: Elevated Sand Mound System, Low Pressure Pipe System, Conventional Trench System, Subsurface Micro Irrigation, Capping Fill Gravity, Capping Fill Low Pressure Pipe, Spray Irrigation System, Infiltrator Advanced Treatment Leachfield (ATL), Infiltrator Advanced Enviro-Septic® (AES) and Discharging System.
What size septic tank do I need in Delaware?
landplan.io sizes the septic tank in Delaware 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 120 gal/day per bedroom, at least 240 gal/day.
Does landplan.io have parcel data in Delaware?
Yes, for 3 of Delaware's 3 counties.