Septic Tank Dimensions (with Drawings)

Concrete vs. Plastic Septic Tank

More than 30% of newly built homes in the United States use on-site wastewater management such as septic tanks. If you want to install a septic tank, you need to be sure it is the correct one. Use this as a guide to determine the size and type of septic tank you need for your home. 

Septic tank dimensions vary based on size and type, but most have a capacity of 1,000 or 1,500 gallons. On average, septic tanks are 4.5 feet wide, 8 feet long, and 6 feet tall. Tanks are buried underground 4 inches to 4 feet deep depending on the site conditions, shape of the tank, and slope. 

Source: Wikipedia

What Is a Septic Tank?

A septic system is a sewerage treatment and disposal system. Waste flows from the house by way of the main sewer line into the septic tank. 

Typically, 40% of the waste is from the toilet, and 30% is from bathing. Additionally, 15% is from laundry, and 10% is from the kitchen. 

A septic tank is a chamber constructed out of concrete, plastic, or fiberglass. Most tanks have one or two compartments, but some tanks have more. The purpose of multiple-compartment tanks is to provide better settling of the solid waste.

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What’s the Average Size of a Septic Tank?

Septic tanks come in a variety of models and sizes. The most common sizes are 1,000 and 1,500-gallon septic tanks. On average, septic tanks are 4.5 feet wide, 8 feet long, and 6 feet tall. The number of bedrooms and number of people in your home will determine the dimensions of the septic tank you need. 

1,000-gallon septic tanks are 8 feet 2 inches long, 5 feet 8 inches wide, and 5 feet 1 inch deep. A 1,000-gallon tank is sufficient for a three-bedroom house. 500-gallon septic tanks can support a 2-bedroom home and are 79 inches long, 45 inches wide, and 56 inches deep.

1,250-gallon septic tanks can support a 4-bedroom home. It is 8 feet 6 inches long, 5 feet 8 inches wide, and 5 feet 9 inches deep. 

A 1,500-gallon septic tank is sufficient for a five-bedroom house. It has a length of 10 feet 9 inches, a width of 6 feet, and a depth of 10 feet 9 inches. 

How to Determine the Size Septic Tank You Need

When installing a septic tank, the correct size is essential to keep your system running efficiently. 

Source: Wikipedia

Here are the factors you should consider when choosing a septic tank that is suitable for your home. 

Your Water Usage

The most effective way to determine the septic tank you need for your home is to calculate your water usage. The septic tank size you need depends on the volume of water it can hold. In the United States, the minimum septic tank size permitted is 1,000 gallons. 

If you use less than 1,240 gallons per day, a septic tank of 1,900 gallons is recommended. If you use less than 900 gallons per day, you should get a 1,500-gallon septic tank.

But if you use less than 700 gallons of water per day, you only need a 1,200-gallon tank. And, if you use less than 500 gallons of water per day, you could get by with a 900-gallon tank.

The Size of Your Property

Consider the square footage of your home when choosing the septic tank you need. If you have a larger home, you will need a larger septic tank. A house that is smaller than 1,500 square feet usually requires a 750 to 1,000-gallon tank. 

If you have a home that is more than 2,500 square feet, you will need a bigger tank. For these homes, it’s best to consider tanks that are bigger than 1,000-gallons.

The Number of Occupants in Your Home

The more people that live in your home, the larger the septic tank should be. For example, if two people live in the house, it will require a smaller septic tank. However, if your home has more than five occupants, you will need a bigger septic tank to manage wastewater effectively.

Keep in mind that the septic tank size also determines the overall efficiency. If your home’s septic tank surpasses its holding capacity, waste can back up into your home. This can cause blockages and flooding and put your family at risk.

Single Compartment Septic Tank Dimensions

500 Gallon Single Septic Tank

A 500-gallon single septic tank has one compartment. It is best for single and multifamily residential septic tank applications. It has an overall height of 56 inches, length of 79 inches, and width of 48 inches. 

The tank has a height of 48 inches from the ground to the centerline of the inlet. It has a height of 45 inches from the ground to the centerline of the outlet. The weight of the 500-gallon single septic tank is 5,000 pounds. 

600 Gallon Single Septic Tank

A 600-gallon single septic tank is best for single and multifamily residential septic tank applications. The overall height is 62 inches, the length is 79 inches, and the width is 48 inches. The tank weighs roughly 5,000 pounds. 

The height of the tank to the centerline of the inlet is 52 inches. The tank’s height from the ground to the centerline of the outlet is 49 inches. 

1,000 Gallon Single Septic Tank

A 1,000-gallon single septic tank has one compartment best for single and multifamily residential septic tank applications. The tank has an overall height of 60 inches, length of 96 inches, and width of 67 inches. The tank weighs 8,000 pounds. 

The tank’s height to the centerline of the inlet is 52 inches. The height of the tank to the centerline of the outlet is 49 inches.

1,250 Gallon Single Septic Tank

A 1,250-gallon single septic tank has one compartment best for single and multifamily residential septic tank applications. It has an overall height of 60 inches, length of 117 inches, and width of 68 inches. The tank weighs 10,400 pounds. 

The height of the tank to the centerline of the inlet is 52 inches. The tank’s height to the centerline of the outlet is 49 inches.

1,500 Gallon Single Septic Tank

A 1,500-gallon single septic tank is best for single and multifamily residential septic tank applications. It weighs approximately 11,700 pounds. The overall height is 60 inches, the length is 150 inches, and the width is 67 inches. 

The height of the tank from the centerline of the inlet is 52 inches. From the centerline to the outlet, the height of the tank is 49 inches.

2,500 Gallon Single Septic Tank

A 2,500-gallon single septic tank has a height of 68 inches, length of 144 inches, and width of 78 inches. The height of the tank to the centerline inlet is 61 inches, and to the centerline outlet is 61 inches. 

The tank weighs roughly 16,000 pounds.

3,500 Gallon Single Septic Tank

A 3,500-gallon single septic tank has an overall height of 98 inches, length of 144 inches, and width of 78 inches. The height of the tank to the centerline inlet is 91 inches. The height of the tank to the centerline outlet is 91 inches. 

This tank is suitable for single and multifamily residential septic tank applications. The tank weighs 20,000 pounds.

Dual Compartment Septic Tank Dimensions 

1,000 Gallon Dual Septic Tank

A 1,000-gallon dual septic tank has two 500-gallon compartments with a solids separator between the first and second compartments. The tank is suitable for single and multifamily residential septic tank applications. It has an overall height of 60 inches, length of 96 inches, and width of 67 inches. 

The tank has a height of 52 inches to the centerline of the inlet. The height to the centerline outlet is 49 inches. The tank weighs 10,000 pounds.

1,250 Gallon Dual Septic Tank

A 1,250-gallon dual septic tank has two 625-gallon compartments with a solids separator between the first and second compartments. The tank is suitable for single and multifamily residential septic tank applications. It has an overall height of 60 inches, length of 117 inches, and width of 67 inches. 

The height of the tank to the centerline inlet is 52 inches. The height to the centerline outlet is 49 inches. The tank weighs 10,700 pounds.

1,500 Gallon Dual Septic Tank

A 1,500-gallon dual septic tank has two compartments. The first compartment holds 1000 gallons, and the second compartment holds 500 gallons. The second compartment is usually the dosing pump section. 

The tank is suitable for single and multifamily septic tank applications. It has a height of 60 inches, length of 150 inches, and width of 67 inches and weighs 11,700 pounds. The height to the centerline inlet is 52 inches, and the height to the centerline outlet is 49 inches.

Triple Compartment Septic Tank Dimensions

1,500 Gallon Triple Septic Tank

A 1,500-gallon triple septic tank has three 500 gallon compartments. There is a solids separator between the first and second compartments, and the third compartment is the dosing pump section. It is best for single and multifamily residential septic tank applications. 

The tank has an overall height of 60 inches, length of 150 inches, and width of 67 inches. The height to the centerline of the inlet is 52 inches, and the height to the centerline of the outlet is 49 inches. The tank weighs 12,000 pounds. 

Related Questions

How do you clean a septic tank?

Septic tanks are self-contained wastewater disposal systems, so they are not connected to the city water supply. Because of this, you are responsible for keeping your system operational, not the city. If you don’t clean your septic tank, it can become clogged with sludge and scum and lead to system collapse.

To prevent your septic tank from failing, you need to keep it clean and regularly have it inspected and pumped. To clean your septic tank, uncover the tank and look for any cracks and leaks. Clean out the filter, measure the depth of the waste inside the tank, then have a professional pump out the waste.

What’s the average cost of a septic tank?

On average, installing a new septic tank system will cost $3,900. For a standard 1,250-gallon tank, the price can range from $1,500 to $5,000. This is ideal for a three or four-bedroom home. 

The cost includes the tank itself, ranging from $600 to $2,100 or more, depending on the type of septic tank. Labor costs are usually included in the installation price. Labor to install the septic tank can range from $1,500 to $4,000. 

What is a septic tank riser?

A septic tank riser is a pipe that installs on the top of your septic tank’s pump out and reaches the surface. It makes accessing your tank easier so you don’t have to dig underground to reach the access ports.

They come in various sizes, so make sure if using one you get the proper size for your septic tank.

Source: Amazon

Stacy Randall

Stacy Randall is a wife, mother, and freelance writer from NOLA that has always had a love for DIY projects, home organization, and making spaces beautiful. Together with her husband, she has been spending the last several years lovingly renovating her grandparent’s former home, making it their own and learning a lot about life along the way.

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