How To Calculate The Size And Capacity Of The Septic Tank | Shape, Size & Dimensions

SEPTIC TANK SHAPE, SIZE & DIMENSIONS

A septic tank is a device that treats wastewater from water closets. In other words, it is a waterproof single-storey, underground tank in which the sewage is stored for a sufficiently long period of time, allowing for the practical digestion of sediment and settled sediments suspended by anaerobic bacterial activity.

Also use: Water-Sump Tank Calculator | Tank Volume Calculator | Sump Volume Calculator

SHAPE OF SEPTIC TANK

The simplest form of septic tank is a single box, rectangular or cylindrical shape. The shape of the septic tank affects the flow velocity of the wastewater and sludge accumulation.

 

The dimension of the septic tank should not be too deep. This is because it may cause a short circuit of the inlet and outlet flows.

 

The septic tank has a large surface area and sufficient depth should always be desired.

 

The rectangular single box tank (three times its width and length) is the most favourable.

 

In some cases, a cylindrical shape with the appropriate size may also be the best choice.

SIZE OF SEPTIC TANK	DIMENSIONS	WEIGHT (kg)	ANCHOR WEIGHT (kg)	SOIL COVER (IN)
5000 gal -18928 liter	17’ L x 8’ W x7.75’ H	41400	30850	24
3000 gal - 11356 liter	13.75’ L x 7. 67‘W x 6.41’H	20300	23320	23
2600 gal - 9842 liter	12.25’L x 7.5’W x 6.08’H	18100	20625	24
2000 gal – 7570 liter	13.5’L x 6.5’W x 5.33’H	16100	15675	19
1600 gal – 6056 liter	12.08’L x 6.5’W x 5.08’H	14000	11270	16
1200 gal – 4542 liter	9.25’L x 6.5’W x 5.08’H	11400	9532	17
1000 gal – 3785 liter
Low Profile	10’L x 67’W x 57’H	9500	8705	17
1000 gal – 3785 liter
Heavy Duty	8’L x x 6.5’W x 5.08’H	9200	8945	18
800 gal – 3028 liter	8’L x 67’W x 57’H	8000	6560	16
600 gal – 2271.25 liter	6.5’L x 56’W x 60’H	6600	3810	14
1600/1400 gal - 6056/5299 liter	14.5’L x 90’W x 73’H	23000	22410	22
1250/750 gal – 4730/2839 liter	13.5’L x 6.5’W x 5.33’H	16400	15725	19
1000/600 gal – 3785/2271 liter	12.08’L x x 6.5’W x 5.08’H	14700	12705	17

 

 

How To Calculate The Size And Capacity Of The Septic Tank In Gallons?

How do we calculate the gallon volume a septic tank can deliver based on the simple measurements we can make?

 

Generally, the residential septic tank is typically 4.5 feet wide x 8.0 feet long x 6 feet high. Your septic tank may be a different size. The best practice is to find and measure the septic tank to make correct calculations.

 

Tanks are generally buried 4 inches to 4 feet deep, depending on local site conditions, shape, slope, and other factors.

 

Here is the basic math for calculating the capacity (volume) of the septic tank in gallons. Measurements taken on the internal dimensions of the septic tank are in feet.

 

HOW TO CALCULATE THE SEPTIC TANK CAPACITY IN GALLONS
Septic Tank In Rectangular	Length x Width x Depth in feet x 7.5 = gallons
Septic Tanks In Round	3.14 x radius squared x depth (all in feet) = cubic capacity. Cubic capacity x 7.5 = gallons capacity.
Septic Tank In Rectangular (alternative method 1)	Length x Width x Depth in feet / .1337 = gallons
Septic Tanks In Round (alternative method 2)	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

 

Notes To The Table Above:

These simple constants and the formula for sizing a rectangular or round tank can help convert the size of a septic tank into cubic feet of sewage:

 

·       One gallon = 231 cubic inches

·       One gallon = 0.1337 cubic feet.

·       1 cubic foot = 7.48 gallons

·       Volume of a cylinder = Pi x radius² x depth

Where,

Radius = half the diameter

Pi = 3.1416

·       Volume of a rectangle = Length x Width x Depth

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