Septic tank size by state / South Atlantic
North Carolina septic tank size
In North Carolina the minimum septic tank for a three-bedroom house is 1,000 gallons, and four bedrooms need the same 1,000 gallons. The figure comes from 15A NCAC 18E .0801 (Septic Tank Capacity Requirements), Table XIV. That matches the 1,000-gallon median of the 47 states listed here.
What the North Carolina rule says
The rule is 15A NCAC 18E .0801 (Septic Tank Capacity Requirements), Table XIV; design flow 15A NCAC 18E .0401, administered by NC Department of Health and Human Services, Division of Public Health, On-Site Water Protection Branch (county health departments permit). In its own words:
(a)(1) "The minimum capacity of any septic tank shall be 1,000 gallons unless otherwise provided for in this Rule." (a)(2) "The minimum capacity of any septic tank serving an individual dwelling unit with five bedrooms or less shall be sized as set forth in Table XIV." Table XIV: 4 or less 1,000; 5 1,250.
Source: 15A NCAC 18E .0801 (Septic Tank Capacity Requirements), Table XIV, read 2026-10-20.
- A grinder or sewage lift pump ahead of the tank doubles the required capacity, and an effluent filter is required.
- Over five bedrooms the tank is sized from design daily flow (120 gallons a day per bedroom).
North Carolina minimum tank size by bedrooms
| Bedrooms | Minimum tank | Versus the median state |
|---|---|---|
| 1 | 1,000 gal | same |
| 2 | 1,000 gal | — |
| 3 | 1,000 gal | same |
| 4 | 1,000 gal | −200 |
| 5 | 1,250 gal | −250 |
| 6 | See note | — |
Over five bedrooms the tank is sized from design daily flow (Table XV).
The first step up comes at 5 bedrooms, from 1,000 to 1,250 gallons. These are minimums: the permit can call for more, and a bigger tank needs pumping less often.
How North Carolina compares with nearby states
Delaware requires 1,000 gallons for three bedrooms; Florida requires 900 gallons for three bedrooms; Georgia requires 1,000 gallons for three bedrooms; Maryland requires 1,000 gallons for three bedrooms; South Carolina requires 1,000 gallons for three bedrooms; Virginia requires 900 gallons for three bedrooms; West Virginia requires 1,000 gallons for three bedrooms. 37 of the 47 states listed here share North Carolina's three-bedroom figure.
Before you size a tank in North Carolina
- Bedrooms, not people, set the size in most rules. Rooms that could be used as bedrooms are usually counted, so check how your permitting office counts a den or a finished basement.
- Garbage disposals, grinder or ejector pumps and large tubs change the answer in many states; the points above list North Carolina's adjustments.
- The tank is only half the system. The drainfield is sized separately from soil tests, and it is usually the bigger cost.
- A private well on the same lot has its own setbacks from the tank and field; the well pump and pressure tank calculators size the water side.
Figures are the state's minimum as written on 2026-10-20. Local health departments can require more; the permit issued for your property governs. See the methodology for how each state was read.