Design standards
The numbers under a permit, not a guess from a catalog.
EPA writes manuals. New York writes Appendix 75-A. The county stamps the plan. Run Table 1 flow, Table 3 tanks, Table 2 setbacks, Table 4A perc, and the 75-A.8 / .9 siting tests. This is a briefing, not a stamped drawing.
House load
Codes size from bedrooms, not from how many people slept there last Tuesday. An expansion attic counts.
Bedrooms
Design flow · Table 1
What Table 3 says
Appendix 75-A Table 1. New construction with 1.6 gpf toilets sizes at 110 gpd per bedroom.
- Design flow
- 330 gpd
- Table 3 equivalent bedrooms
- 3
- Minimum tank
- 1,000 gal
- Minimum liquid surface
- 27 ft²
- Two × daily flow (other codes)
- 1,000 gal
NY uses the bedroom table, not two-times-flow, and floors at 1,000 gallons for 1–3 bedrooms. Two compartments, an outlet baffle, and a listed effluent filter are construction notes, not extras.
| Bedrooms | Gallons | Liquid surface |
|---|---|---|
| 1–3 | 1,000 | 27 ft² |
| 4 | 1,250 | 34 ft² |
| 5 | 1,500 | 40 ft² |
| 6 | 1,750 | 47 ft² |
| Each extra | +250 | +7 ft² |
Tank gallons and liquid surface follow NY Appendix 75-A Table 3. Design flow follows Table 1 (110 / 130 / 150 gpd per bedroom). Perc rates follow Table 4A. Setbacks follow Table 2. Raised and mound siting follow 75-A.9. County health departments may be stricter. Not a permit.