Reference
The standard sizing most states start from. Massachusetts, California and a few others set higher floors — check your state page.
| Dwelling | Design flow | Minimum tank | With garbage disposal |
|---|---|---|---|
| 1 bedroom | 450 gpd | 1,000 gal | 1,250 gal |
| 2 bedrooms | 450 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 |
| 6 bedrooms | 900 gpd | 2,000 gal | 2,250 gal |
| 7 bedrooms | 1050 gpd | 2,500 gal | 2,750 gal |
| Soil | Application rate | Absorption area | Trench length at 3 ft |
|---|---|---|---|
| Gravel / coarse sand | 1.20 gpd/sq ft | 375 sq ft | 125 ft |
| Sand | 0.80 gpd/sq ft | 562 sq ft | 188 ft |
| Sandy loam | 0.60 gpd/sq ft | 750 sq ft | 250 ft |
| Loam | 0.45 gpd/sq ft | 1,000 sq ft | 333 ft |
| Silt loam | 0.30 gpd/sq ft | 1,500 sq ft | 500 ft |
| Clay loam | 0.20 gpd/sq ft | 2,250 sq ft | 750 ft |
| Clay | 0.10 gpd/sq ft | 4,500 sq ft | 1,500 ft |