Some homes can’t connect to traditional sewer systems, so they rely on septic tanks instead. A septic tank provides reliable waste removal including the management of both liquid wastewater and solid waste, and helps prevent the risk of plumbing damage and groundwater contamination. There are multiple types of septic tanks available, and choosing the right one depends on several factors:
Key Factors in Choosing a Septic Tank
- House size and occupancy: The number of rooms in your house, as well as the number of people using its facilities, helps determine the best septic tank dimension for your needs. Choosing the right septic tank size ensures efficient waste management and long-term reliability.
- Water usage: Households that use large amounts of water with laundry machines, dishwashers, bathtubs, and more may need a more advanced system to manage their daily output. Understanding how much wastewater your home produces daily is crucial in selecting the appropriate system.
- Budget: There are various types of tanks to choose from, each offering different advantages. If you have a limited budget, a less expensive tank made from a lightweight material like plastic septic tanks could be ideal.
- Local regulations: Every town and municipality sets its own standards for septic systems, which can influence the type of tank you can install and the materials it must be made of. You can find Boulder’s septic tank regulations in this document.
Before we delve into the details of septic tank size dimensions, let’s look at the different types available.
Types of Septic Tanks
There are three common types of septic tanks you can buy for a house: concrete, plastic (or polyethylene), and fiberglass.
- Concrete Tanks: Concrete is the most common material used for septic tanks and is considered the gold standard due to its long lifespan. With proper maintenance, a concrete septic tank can last 30-40 years.
- Plastic/Polyethylene Tanks: These tanks are durable, affordable, flexible, and lightweight compared to concrete. Polyethylene is a highly durable type of plastic, one of the most commonly used materials in the world. It’s non-hazardous and suitable for a wide range of applications, making it an excellent choice for a budget-friendly septic tank.
- Fiberglass Tanks: Fiberglass tanks are reinforced with plastic and are easy to install. They’re stronger than plastic systems and naturally resistant to bacteria.
All of these tanks can last 20-30 years, but if you’re really looking for the greatest long-term investment, a concrete tank is the best choice. However, many customers prefer the ease of installation and other benefits of plastic and fiberglass septic tanks.
Our team can help you make the right decision for your unique situation if you need more clarity on the pros and cons of each type of septic tank.
Now that we understand the different options available, we can take a closer look at septic tank systems and how to choose the right one for your home.
Types of Septic Systems
- Anaerobic System: This type of tank uses gravitational force and anaerobic bacteria to treat wastewater before moving it to a drain field.
- Above-ground Septic System: When traditional in-ground systems aren’t an option or preferred, above-ground tanks can work instead. The tank and drain field will be located above ground, so many homeowners also invest in landscaping to avoid eyesores on their property.
- Aerobic Septic System: The aerobic system uses oxygen to promote the growth of aerobic bacteria, which break down waste faster than anaerobic bacteria.
- Mound System: Mound septic systems are a type of above-ground septic tanks that direct wastewater to a drain field in a sand mound above natural soil.
- Pressure System: A pressurized pump moves wastewater to the drain field. Its motorized process helps ensure efficiency.
- Recirculating Sand or Gravel Filter Septic System: Waste is moved through a sand or gravel filter repeatedly before being dispersed to the drain field. In some cases, the water can be reused for irrigation.
- Bottomless Sand Filter Septic System: This type of system relies entirely on sand to treat wastewater; low pressure is applied to remove pollutants as the water passes through the sand. Although efficient, these systems have high maintenance costs.
Choosing the right system will vary depending on your needs and budget. It’s important to consider more than just initial costs; every septic tank requires routine cleaning and maintenance to operate effectively. More advanced systems will cost more, so you should carefully consider the total cost of ownership before settling on any particular system.
We know this is an extensive process and are here to help. Our professional team will work with you every step of the way to compare and contrast systems until you find the perfect one for your needs.
Septic Tank and Sewage System Compatibility
Your septic tank must be compatible with your overall sewage system to function properly. Ensuring proper drainage and filtration will help prevent backups and maintain a healthy home environment.
Septic Tank Sizes, Capacity, and Recommendations
When selecting a septic tank for your home, it’s important to consider both size dimensions and capacity, as they play a crucial role in the system’s overall performance. The capacity refers to the volume of wastewater the tank can handle, typically measured in gallons, while the physical size refers to the tank’s dimensions (length, width, and height).
Minimum and Recommended Septic Tank Capacity
In Boulder, CO, the minimum septic tank capacity is based on the number of bedrooms in your home. The minimum septic tank size dimensions ensure that the system can handle basic household waste without risk of overflow. However, the ideal septic tank size may vary based on your household’s water usage and specific needs.
Minimum Septic Tank Capacity:
- 2 or 3 bedrooms: 1,000 gallons
- 4 bedrooms: 1,500 gallons
- Each additional bedroom: +250 gallons
For homes with higher water usage (due to frequent laundry, multiple bathrooms, or large household appliances), a larger tank may be necessary to ensure long-term reliability.
Recommended Septic Tank Sizes:
- 2-Bedroom Home: 1,000 gallons (may increase based on high water usage)
- 3-Bedroom Home: 1,000 to 2,000 gallons
- 4-Bedroom Home: 1,500 to 2,500 gallons
- 5-Bedroom Home: 1,750 to 3,000 gallons
These ranges account for average water consumption in households. Keep in mind that larger homes with increased water usage will require a larger tank to prevent backups and overflows.
Septic Tank Dimensions and How They Relate to Capacity
The physical size dimensions of a septic tank typically average around 4.5 feet in width, 8 feet in length, and 6 feet in height. These dimensions can vary based on tank material (concrete, fiberglass, polyethylene) and manufacturer. Larger homes (over 2,500 square feet) will generally require a tank with greater size dimensions to handle increased wastewater production.
As for the capacity, this refers to the volume of wastewater the tank can manage:
- A 2 or 3-bedroom home typically needs a tank with 1,000 gallons of capacity.
- A 4-bedroom home usually requires 1,500 gallons, and
- Larger homes or those with more residents will need a tank with a higher capacity.
Septic Tank Capacity & Home Size Correlation:
| Number of Bedrooms | Recommended Tank Size (Gallons) | Average Home Size (Square Feet) |
|---|---|---|
| 1 bedroom | 1,000 to 1,500 gallons | 700 to 1,500 sq ft |
| 2-3 bedrooms | 1,000 to 2,000 gallons | 1,500 to 2,200 sq ft |
| 4 bedrooms | 1,500 to 2,500 gallons | 2,200 to 3,000 sq ft |
| 5 bedrooms | 1,750 to 3,000 gallons | 3,000 to 3,500 sq ft |
Keep in mind that local building codes and regulations will influence septic tank size requirements. It’s also important to factor in water usage and wastewater produced to know precisely which size septic tank is perfect for your home.
Choosing the Right Septic Tank
When selecting a septic tank, both the size dimensions and capacity should align with your household’s needs. Consider your home’s square footage, the number of bedrooms, daily water consumption, and the number of people living in the household. A professional can help assess these factors to determine the optimal septic tank size for your home.
By choosing a septic tank that balances both the right size dimensions and capacity, you’ll ensure efficient waste management and prevent issues like tank overload or backups. This choice will also promote long-term system reliability and help avoid expensive repairs or replacements.
How to Calculate Septic Tank Size
There are two factors you should consider when calculating septic tank size:
- Estimated daily water usage: Most people use around 70-100 gallons of water per day. Multiply these figures by the number of people in your household. This will give you a good starting range for what size septic tank you should buy.
- Consider the number of bedrooms: The general industry rule is that a septic tank should account for at least two people per bedroom.
Small Septic Tank Considerations
For homes with limited space or low water usage, a small septic tank might be a suitable choice. These tanks are designed for efficiency and affordability but require more frequent maintenance to prevent overflow issues.
Septic Tank Shape
Septic tanks typically come in two shapes: cylindrical and rectangular. The rectangular shape is more common and easier to install. Plastic or polyethylene tanks tend to be cylindrical for better weight distribution.
Both shapes are effective, and a professional can help determine which shape would be ideal based on your material preference and home size.
What Size Septic System Do I Need?
The right septic tank for your home will depend on how much water you use and the square footage of your house. More bedrooms generally mean more people, which requires a larger septic tank to accommodate their needs.
The more wastewater a home generates, the larger its septic tank should be.
Please contact us to learn more about septic tank installation in Boulder, CO. Our contractors will be happy to help you determine the perfect size and type of tank for your home.
