Septic Tank Dimensions (Standard Sizes & Capacity)

In this guide to septic tank dimensions you’ll see standard septic tank sizes with holding capacity for rectangular & circular tanks, and factors for choosing home tank 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 commonly constructed with concrete, fiberglass, or plastic to treat household wastewater and ensure that they do not pollute any of our water supplies. Most septic tanks have two compartments, but others can even 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 that is 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 and its size or capacity. All septic tanks need to be buried underground at 4 inches or ten 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 septic tanks have a water capacity of 1000 to 1500 gallons. 

How Many Gallons Is A Standard Septic Tank?

The capacity or hold of each septic tank will depend on the number of people are living in a home on an average day and their daily water usage. Septic tank 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 septic tank close to that number. 

500 Gallon Septic Tank Dimensions

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 septic tank 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 septic tanks available. It will usually have dimensions of 97 inches or 246 centimeters for length, a width of 48 inches or 122 centimeters, and a height of 42 inches or about 107 centimeters. 

1000 Gallon Septic Tank Dimensions

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

A regular 1000 gallon rectangular septic tank 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 a more rounded plastic septic tank 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 the width and height. 

1500 Gallon Septic Tank Dimensions

There are even larger septic tanks with an even larger water capacity, and one of them is the 1500 gallons septic tank, 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 when it comes to their dimensions. 

A rectangular septic tank with a holding capacity of 1500 gallons has 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 Dimensions 

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

And 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. 

Concrete Septic Tank Sizes

Most septic tanks 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 that have 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 gallons of septic tanks for the wider variety with dimensions of 68 or 173 centimeters for the 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 factors will help you purchase the best you can find to ensure that everything will be working 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 a 750 to 1000 gallons tank. For homes at 2500 and over, going for a septic 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 septic tank 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 septic tank’s size is the number of bedrooms in your household. For a smaller house with a single or two bedrooms, the best septic tank size will have a holding capacity of 750 gallons. 

What Size Septic Tank For 3 Bedroom House?

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

How Big Of Septic Tank For 4 Bedroom House?

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

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