Septic Tank Dimensions (Standard Sizes & Capacity)

In this guide to septic tank dimensions you’ll see standard wastewater container sizes with holding capacity for rectangular & circular tanks, and factors for choosing capacity.

Septic tanks are probably one of the most life-saving innovations made by humans in collaboration with nature in history. These underground chambers are the unsung heroes of plumbing and commonly constructed with concrete, fiberglass, or plastic to treat household wastewater. Their job is to ensure that they do not pollute any of our water supplies. 

Creating these systems requires skilled plumbers with experience and understanding of leach fields, pipes, and drains. Most septic containers have two compartments, but others can have more depending on the design and other factors.

Choosing the best septic tank size for your home is vital to ensuring that this waste management treatment system will work efficiently so that any costly repairs or, worse, water contamination harmful to everyone’s health will be avoided in the long run.

Standard Septic Tank Size

There are a variety of septic tanks available in the market; each type will depend on its kind, size, or capacity. All sewage tanks need to be buried underground at 4 inches or 10 centimeters to 4 feet or about 1.2 meters, depending on the tank’s shape, slope, and site conditions, among others. 

The standard septic tanks will be 4.5 feet or 54 inches wide, with a length of 8 feet or 96 inches and a height of 6 feet or 72 inches. Most tanks have a water capacity of 1000 to 1500 gallons. 

Rectangular Tank Measurement Chart

Capacity (Gal.)	Height (H)	Length (L)	Width (W)
500	56″	79″	48″
1000	60″	96″	67″
1500	60″	150″	67″

Circular Tank Sizing

Capacity (Gal.)	Height (H)	Length (L)	Width (W)
500	42″	97″	48″
1000	60″	101″	60″
1500	51″	157″	69″

How Many Gallons Is A Standard Septic Tank?

The capacity or hold of each septic tank will depend on the number of people living in a home on an average day and their daily water usage. A tank’s holding capacity will also depend on the size of a home since water capacity can range from the smaller 750 gallons to 1250 gallons for bigger homes. 

Another consideration is the amount of water that each person uses, whether in the kitchen or the bathroom. The average water usage for one person a day is 60 to 70 gallons of water; multiply that by the number of individuals in the household and get the holding container close to that number. 

500 Gallon Tank Capacity

500 gallon septic tanks are available for smaller residences and single-family homes. They come in many shapes and sizes that depend on whether you are getting a rectangular or a circular one. 

A rectangular 500 gallon tanks will have an overall height of 56 inches or 142 centimeters, a length from left to right of 79 inches or 201 centimeters, and a width of 48 inches or about 122 centimeters. Most will be steel reinforced for added protection to your water system. 

There are also 500 gallon circular tanks available. It will usually have dimensions of 97 inches or 246 centimeters in length, a width of 48 inches or 122 centimeters, and a height of 42 inches or about 107 centimeters. 

1000 Gallon Tank

A more acceptable option for a much bigger household is the 1000 gallon tank. Reinforced steel tanks are buried underground and can withstand the pressure of soil to ensure a lower chance of water contamination. 

Regular 1000 gallon rectangular septic tanks will have an overall height of 60 inches or 152 centimeters, a length of 96 inches or about 244 centimeters, and an overall width of 67 inches or 170 centimeters. 

For more rounded plastic tanks with a capacity of 1000 gallons, it will have dimensions of 101 inches or 257 centimeters in length and 60 inches or 152 centimeters for both width and height. 

1500 Gallon Tank

There are even larger septic tanks with an even more water capacity, and one of them is the 1500 gallon model, which can be utilized for bigger houses and even small businesses. Although their holding capacity will be the same, it will differ across the board regarding their dimensions. 

Rectangular  tanks with a holding capacity of 1500 gallons have an overall height of 60 inches or 152 centimeters, a length from one end to the other of 150 inches or 381 centimeters, and a width of 67 inches or 170 centimeters. 

There are also more cylindrical ones with a dimension of 157 inches or 399 centimeters for the length, a width of 69 inches or 175 centimeters, and a height of 51 inches or 130 centimeters. 

Round Septic Tank System Dimensions 

A round septic tank, like the regular two-chambered rectangular ones, will have different dimensions depending on the tank’s holding capacity. You can get a smaller circular tank holding 330 gallons with a height of 63 inches or 160 centimeters and a width of 49 inches or 124 centimeters. 

There are also bigger ones that hold 500 gallons of capacity with a tank height of 67 inches or 170 centimeters and a width of 59 inches or about 150 centimeters. 

Sizes For A Concrete Septic Tank

 

Most underground wastewater containers are usually steel-reinforced concrete tanks that are rectangular. They are tried and tested and will mostly have two chambers depending on their length and how big the household is. 

There are many concrete septic tanks, and you can go for the smallest ones at 500 gallons with a height of 56 inches or 142 centimeters, a length of 79 inches or 201 centimeters, and a width of 48 inches or 122 centimeters. 

There are 2500 gallon tanks for the wider variety with dimensions of 68 or 173 centimeters in height, a length of 144 inches or 366 centimeters, and a width of 78 inches or 198 centimeters. 

How Big Of A Septic Tank Do I Need? 

There are many ways to determine what size of septic tank you will need for your home, and considering these specifications will help you purchase the best you can find to ensure that everything will work out smoothly. 

The first factor you can consider is looking at your household’s daily water use. In most states, the minimum tank size is 1000 gallons, and this size is excellent for any home that uses at least 500 gallons of water in a day. 

Another factor of consideration can also be the size of your property. For example, the best septic tank size for a small 1500 square feet home is the size that holds 750 to 1000 gallons. For homes at 2500 and above, going for a tank range of 1000 gallons and above is the best choice. 

The number of house occupants is also another factor to consider. The more people living in a place at a given time, the larger the household’s wastewater container should be. 

What Size Septic Tank For 2 Bedroom House?

Aside from occupants, property size, and water usage, another factor you can count on deciding on your wastewater container size is the number of bedrooms in your household. For a smaller house with a single or two bedrooms, the best tank size will have a holding capacity of 750 gallons. 

What is the Septic Tank Capacity For 3 Bedroom Houses?

For a household with three bedrooms, among other rooms like the kitchen, the living room, or the dining area, the best tank for this size is any product with a hold of 1000 gallons. 

How Big Is A Septic Tank For a 4 Bedroom Home?

The more bedrooms there are in a home, the larger the wastewater container should be, so for a four-bedroom house, the best size for a septic system is the one with a holding capacity of 1200 gallons. You can go up to 1500 gallons capacity for houses with five to six bedrooms. 

Visit our septic tank pros and cons guide for more related content.