New York · 10 NYCRR Appendix 75-A
Septic system requirements in New York
Tank sizes, drainfield rules, setbacks, permits, and real costs — pulled from New York's own code rather than a national average.
- 3-bedroom tank
- 1,000 gal
- Design flow
- 110 gpd/BR
- Typical install
- $14,000–$38,000
- Permit fee
- $250–$1,200
- Well setback
- 100 ft
- Permitted by
- County / local
Septic tank sizes required in New York
New York sizes systems on a design flow of 110 gallons per day per bedroom. The tank must meet both the bedroom table below and a 2× daily-flow detention requirement — whichever produces the larger number governs.
| Bedrooms | Design flow | Code minimum | Recommended |
|---|---|---|---|
| 1 bedroom | 110 gpd | 1,000 gal | 1,000 gal |
| 2 bedrooms | 220 gpd | 1,000 gal | 1,000 gal |
| 3 bedrooms | 330 gpd | 1,000 gal | 1,000 gal |
| 4 bedrooms | 440 gpd | 1,250 gal | 1,250 gal |
| 5 bedrooms | 550 gpd | 1,500 gal | 1,500 gal |
| 6 bedrooms | 660 gpd | 1,750 gal | 2,000 gal |
Source: 10 NYCRR Appendix 75-A. The recommended column rounds the governing requirement up to a tank size manufacturers actually stock.Run your own numbers →
Drainfield size and cost by soil type
For a three-bedroom home in New York at 330 gpd. This single table explains most of the variation between quotes — the area scales inversely with how fast your soil accepts water, and the drainfield is the largest line item in the job.
| Soil | Loading rate | Absorption area | With reserve | Typical total install |
|---|---|---|---|---|
| Medium sand | 0.8 gpd/ft² | 413 ft² | 826 ft² | $12,700 |
| Sandy loam | 0.5 gpd/ft² | 660 ft² | 1,320 ft² | $15,500 |
| Loam | 0.4 gpd/ft² | 825 ft² | 1,650 ft² | $17,300 |
| Silt loam | 0.3 gpd/ft² | 1,100 ft² | 2,200 ft² | $20,400 |
| Clay loam | 0.2 gpd/ft² | 1,650 ft² | 3,300 ft² | $26,600 |
Estimates use New York's cost index of 1.25× the national average. Build a line-item estimate →
Permits and who issues them
County health departments and NYSDOH district offices permit residential systems under 10 NYCRR Appendix 75-A; DEC handles larger flows.
| Permit required | Yes |
|---|---|
| Typical fee | $250 – $1,200 |
| Soil evaluation | Required before permit |
| Licensed installer | Not required statewide |
| Turnaround | 3–10 weeks |
| Ongoing inspection | Required in some watersheds, notably the NYC watershed counties |
| Reserve area | 100% replacement area required |
Minimum setback distances
Measured horizontally from the drainfield unless noted. Local rules are frequently stricter, and on a small lot these numbers — not the soil — often decide the layout.
| Private water well | 100 ft |
|---|---|
| Well (septic tank) | 50 ft |
| Property line | 10 ft |
| Surface water | 100 ft |
| Building foundation | 10 ft |
Regulatory contact
New York State Department of Health — Residential Onsite Wastewater
www.health.ny.gov · 518-402-7650
What makes septic hard in New York
The New York City watershed counties — Delaware, Greene, Putnam, Sullivan, Ulster, Westchester — operate under separate, stricter rules with their own inspection and maintenance requirements.
Long Island sits over a sole-source aquifer, and Suffolk County now requires nitrogen-reducing systems for most new and replacement installs.
Adirondack and Catskill sites combine shallow bedrock with steep slopes and short seasons.
Things that catch people out
- Suffolk County's innovative/alternative system requirement adds roughly $10,000–$20,000 versus a conventional system, partially offset by a county grant.
- Appendix 75-A caps residential coverage at 1,000 gpd. Above that you are into DEC territory and a different, slower process.
New York septic questions
What size septic tank do I need in New York?
A three-bedroom home in New York requires a minimum 1,000 gallon tank under 10 NYCRR Appendix 75-A. Design flow is 110 gallons per day per bedroom, and the tank must also hold 2 times daily flow, so the practical recommendation is 1,000 gallons.
Do I need a permit for a septic system in New York?
Yes. County health departments and NYSDOH district offices permit residential systems under 10 NYCRR Appendix 75-A; DEC handles larger flows. Fees typically run $250 to $1,200, with a turnaround of about 3–10 weeks. A soil evaluation or percolation test is required before a permit is issued.
How much does a septic system cost in New York?
A conventional system for a three-bedroom home typically runs $14,000 to $38,000 installed. Soil quality moves this more than anything else — on tight clay requiring a mound, budget two to three times the low end.
How far must a New York drainfield be from a well?
100 feet from a private water well, with the septic tank itself allowed at 50 feet. Local rules can be stricter.
Sources
Every figure on this page traces to one of these documents.
- 10 NYCRR Appendix 75-A — Wastewater Treatment Standards — Residential Onsite Systems · verified 2026-09-18
- 10 NYCRR App. 75-A — Appendix 75-A rule text · verified 2026-09-18