North Carolina septic rules
North Carolina septic tank size & cost
North Carolina rewrote its rules in 2024 — old charts are wrong now. A typical new 3-bedroom system in North Carolina runs about $6,900–$11,100 installed by our line-by-line estimate. Below: the state's actual size rule, the full table, and where every number comes from.
Rule: 15A NCAC 18E .0801, Tables XIV & XV (rules effective January 1, 2024) · Administered by North Carolina Department of Health and Human Services · Read the official text · Checked 2026-11-08
North Carolina's rule, in plain words
On January 1, 2024, North Carolina replaced the septic rules its charts had been copied from for decades. Under the current rule (15A NCAC 18E .0801), homes up to four bedrooms all sit at 1,000 gallons — the old 900-gallon small-home row is gone — five bedrooms take 1,250, and six or more are sized by formula (Table XV): 1,500 gallons plus 250 per bedroom past six.
If a chart shows you 900 gallons for a small North Carolina home, it is quoting the pre-2024 rulebook. This page follows the current one, and the calculator applies the Table XV formula for larger homes.
The North Carolina size table
| Bedrooms | Minimum tank (gal) | With garbage disposal |
|---|---|---|
| 1 | 1,000 | 1,500 |
| 2 | 1,000 | 1,500 |
| 3 | 1,000 | 1,500 |
| 4 | 1,000 | 1,500 |
| 5 | 1,250 | 1,875 |
| 6 | 1,500 | 2,250 |
Garbage disposal: With a garbage disposal, North Carolina multiplies the required capacity by 1.5.
North Carolina replaced its septic rules on January 1, 2024 — older charts still circulating online (900 gal for small homes) are the pre-2024 rules and no longer apply.
Check your North Carolina home
State minimum — your county can require more. Estimate this system's cost →
What a North Carolina system costs
Our estimator prices a conventional 3-bedroom system in North Carolina (lower-cost area, 1,000-gal tank) at $6,900–$11,100 installed, assembled from a soil test, the permit, the tank at published prices, drainfield material, fittings and labor. Build your own estimate →
How North Carolina compares (3-bedroom minimum)
Full ten-state chart: septic tank size chart.
Other states we've checked
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