New Jersey · New Jersey Administrative Code 7:9A
NJDEP writes the standards and local health agencies issue permits, with county health departments involved in many jurisdictions.
Minimum tank
One to three bedroom dwelling.
Design flow
Held two days for settling.
Cost index
Regional labour and permits.
Sets the design flow and the legal minimum.
Code sizes on bedrooms, not people.
Used to size the matching drainfield. Unsure? Sandy loam is the common default.
Coastal plain sands in the south, piedmont clay and shale through the centre, and rocky highlands in the northwest. The Pinelands region has its own overlay authority with stricter rules.
Conventional disposal beds and trenches. Advanced treatment for nitrate dilution is required in areas where groundwater standards apply, notably in the Pinelands and on smaller lots.
| Dwelling | Design flow | Minimum tank | With disposal |
|---|---|---|---|
| 1 bedroom | 300 gpd | 1,000 gal | 1,250 gal |
| 2 bedrooms | 300 gpd | 1,000 gal | 1,250 gal |
| 3 bedrooms | 450 gpd | 1,000 gal | 1,250 gal |
| 4 bedrooms | 600 gpd | 1,250 gal | 1,500 gal |
| 5 bedrooms | 750 gpd | 1,500 gal | 1,750 gal |
New Jersey requires soil logs and permeability testing under 7:9A, and the Pinelands Commission imposes an additional layer in the Pinelands Area, where nitrate dilution modelling can determine minimum lot size.
The state sets a floor. These New Jersey counties are where the largest septic populations sit, and where local requirements most often exceed it.
| County | What makes it different |
|---|---|
| Ocean | Large septic population, Pinelands overlay in part |
| Burlington | Extensive Pinelands coverage |
| Morris | Highlands with rock and slope |
| Sussex | Rural northwest, shallow bedrock |
| Hunterdon | Rural lots on shale and limestone |
| Atlantic | Coastal plain with Pinelands areas |
A three-bedroom home at 150 gallons per bedroom produces 450 gallons per day of design flow. On sandy loam that needs roughly 750 square feet of absorption area. On clay loam it rises to about 2,250 square feet, and on clay a conventional field is usually not permitted at all. Run your own soil class through the drainfield calculator.
Advanced treatment systems require operation and maintenance permits. Use the pump schedule calculator to work out the interval for your tank size and household.
Regional labour and permit costs in New Jersey run about 130% of the national baseline. Here is what typical installations land at for a three-bedroom home:
| System type | Typical installed cost in New Jersey | When it applies |
|---|---|---|
| Conventional gravity | $11,700 – $20,800 | Good soil, adequate depth to water |
| Chamber system | $12,900 – $23,900 | Alternative to gravel trenches |
| Mound system | $22,200 – $43,700 | Shallow water table or thin soil |
| Aerobic treatment | $18,700 – $37,400 | Clay soil or small lots |
| Tank pump-out (service) | $420 – $840 | Every 3–5 years |
Replacing an existing system costs more than these figures — old-system removal and re-permitting add to every line. The replacement cost calculator covers that case, and the cost estimator adjusts all of the above for your bedroom count and soil.
Verify before you build. The figures above are state minimums compiled for planning, drawn from New Jersey Administrative Code 7:9A, Standards for Individual Subsurface Sewage Disposal Systems. County and health district rules routinely exceed them, code text changes, and only New Jersey DEP — Bureau of Nonpoint Pollution Control or your local health department can confirm what applies to your parcel.
Send your sizing numbers to installers who work under New Jersey rules every day.