The required septic tank size and all the details you want to know!
The required septic tank size and all the details you want to know!
A septic tank is an underground chamber of concrete, fiberglass or plastic through which domestic wastewater (wastewater) flows for basic treatment. The settling and anaerobic processes reduce solids and organic matter, but the treatment efficiency is only moderate (this is called “pretreatment”).
Septic tank size requirements and all details The septic tank system is a simple on-site sanitary installation (OSSF). They can be used in areas not connected to the sewer network, such as rural areas.Treated liquid wastewater is usually discharged to a septic tank for further treatment. However, groundwater contamination can occur and can be a problem.
An illustration with written descriptions of a septic tank uses a cross-sectional view to detail the internal process and components.
| Necessary septic tank size table based on daily discharge in gallons | |
| Average sewage flow – Gallons per day | Minimum septic tank size in gallons capacity necessary effect |
| 0-500 | 900 |
| 601-700 | 1200 |
| 801-900 | 1500 |
| 1001-1240 | 1900 |
| 2001-2500 | 3200 |
| 4501-5000 | 5800 |
| Septic tank size in gallons based on the number of compartments | ||
| Number of compartments | Minimum septic tank capacity (gallons) | Minimum septic tank liquid area (sq.ft) |
| 0 compartment | 750 gal. (2) – obsolete in NYS | |
| 1, 2, or 3 compartments | 1,000 gallons | 27 sq. ft. |
| 4 compartments | 1,200 gallons | 34 sq. ft. |
| 5 compartments | 1,500 gallons | 40 sq. ft. |
| 6 compartments | 1,750 gallons | 47 sq. ft. |
Note on the Sump Size Chart above
Origin: New York State NYS75-A. Wastewater treatment standards
| How to calculate septic tank capacity in gallons | |
| Round Sump | 3.14 x radius squared x depth (all in feet) = cubic capacity. Cubic capacity x 7.5 = gallons capacity. |
| Rectangular Sump | Length x Width x Depth in feet x 7.5 = gallons |
| Rectangular Sump (alternative method 1) | Length x width in inches / 231 = gallons per inch of septic tank depth. Multiply this number by septic tank depth in inches to get gallons |
| Rectangular Septum (alternative method 2) | Length x Width x Depth in feet / .1337 = gallons |
CALCULATION EXAMPLE – Calculation example of septic tank size, capacity or volume in gallons
One gallon of water has a volume of 0.1337 cubic feet. For rectangular septic tanks, multiply the depth (or “height” inside in feet by the width in length. Divide this number by 0.1337 to calculate the number of gallons in the septic tank.)
Example 1
How many gallons are in a 4 foot tank.depth x 5 feet. Septic tank 8 feet wide x 8 feet long?
If the tank size is 4 feet. x 5 meters.x 8 pins. = 160 cubic feet. Use the conversion factor to convert cubic feet to gallons, 160 / 0.1337 = 1196 – or approximately a 1200 gallon tank. One cubic foot of volume can hold 7.481 gallons of liquid. So, the second way to calculate the actual size or capacity of the septic tank in gallons is to multiply the volume of the septic tank in cubic feet by this constant, which we round to 7.5 gallons/ cubic feet.
