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!

How Septic Tanks Work in France1 768x500 1

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
Septic tank size in gallons based on the number of compartments
Number of compartmentsMinimum septic tank capacity (gallons)Minimum septic tank liquid area (sq.ft)
0 compartment750 gal. (2) – obsolete in NYS
1, 2, or 3 compartments1,000 gallons27 sq. ft.
4 compartments1,200 gallons34 sq. ft.
5 compartments1,500 gallons40 sq. ft.
6 compartments1,750 gallons47 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 Sump3.14 x radius squared x depth (all in feet) = cubic capacity. Cubic capacity x 7.5 = gallons capacity.
Rectangular SumpLength 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
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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.