What Size Septic Tank Do I Need

Article Summary

For this article, we will be discussing underground septic tanks, and size refers to the septic tank&#;s total volume handling capacity. See our article on above ground septic tanks for more information on these tanks and systems.

For more information, please visit small septic tank for sale.

The requirements for minimum septic tank capacity depend on several factors. State, county and/or city guidelines can mandate approved sizes as well as tank material and placement. The soil conditions and regional geography have a large role in system effectiveness, which can impact drain field size and septic tank size. Whether the septic tank is intended for residential or commercial use will affect septic tank size per regulations; here we discuss home use. The specific septic tank system in place or that will be installed can also change the needed tank size.

In short, the size of septic tank needed will depend on: (1) the specific septic system type; (2) local government regulations; (3) suitability of the ground geology, and (4) the expected volume of wastewater based on size of the home.

Contrary to some belief, polyethylene (i.e. plastic) septic tanks make excellent choices for modern septic tank systems. Plastic septic tanks are much more resistant to cracking versus concrete septic tanks. Also, plastic septic tanks will not rust, are weatherproof, watertight, cheaper, lightweight, are easier to install and, if installed correctly, will not float.

1) The Specific Septic System Type

There are 7 types of septic tank systems and the tank size needed may vary by the specific system you plan to use. An overview of each system type and their size requirements are beyond the scope of this article. Here, when referring to system type, we mean conventional, gravity-fed anaerobic septic systems. The anaerobic septic system is the most common and the one that most visualize when they think of a septic tank.

The 7 common types of septic systems are listed below, and new polyethylene septic tanks can be used in most, if not all, of these systems that require a tank:

1. Conventional, Gravity-Fed, Anaerobic System
2. Above Ground Septic System
3. Pressure System
4. Aerobic System
5. Mound System
6. Recirculating Sand or Gravel Filter System
7. Bottomless Sand Filter System

If your septic tank system is anything but a conventional, anaerobic system, the guidelines in this article may not fully apply.

2) Local Government Regulations

Local government regulations for septic tanks vary widely across the United States. This is due to the vastly different soil geographies and water features that change by state and can even sometimes change by a few miles. This is why checking with local government regulations is such a key factor when finding the right septic tank size and the right location on the property for installation.

For an example and an informational overview of codes, rules, regulations often put forth by governing departments, as well as common terminology and definitions, review the Wastewater Treatment Standards &#; Residential Onsite Systems document from the New York State Department of Health

3) Suitability of the Ground Geology

The underground soil type has a key role in system effectiveness and therefore septic tank size. This point is heavily related to local government regulations. It is tied into the requirements and recommendations of a designated department that oversees septic tank installations, often the department of health. To find how suitable the ground is for a septic tank system, a certified professional must come out to the proposed installation area to perform certain tests. The most common test is a soil percolation evaluation, often referred to as the perc test. A perc test will determine how viable the underground soil is to properly handle and filter septic tank effluent.

Scheduling for these local ground geology tests can be the responsibility of the contractor installing the septic tank or the landowner. If you are installing a septic tank yourself, it will be your responsibility to contact your local oversight department to come perform perc tests and/or ground area evaluation. The results of the analysis and tests will decide if the desired location is acceptable and whether a specific septic tank system or size will be necessary.

4) The Expected Volume of Wastewater

The most important point to determine what size septic tank is needed is the average volume of wastewater that will be produced for the septic tank to handle. In a septic system only residence, all wastewater ends up at the septic tank unless a separate system for handling greywater is in place. Much research has gone into calculating and approximating these values for residential homes, commercial structures, and facilities. Most governmental recommendations for the smallest septic tank capacity in home use is based on the number of bedrooms in the house.

The recommendation for home use is a gallon septic tank as a starting point. The gallon size tank is a minimum and *can be suitable for a 2 bedroom, 3 bedroom house. Some recommendations say to add an extra 250 gallons of septic tank capacity for each bedroom over 3 bedrooms. Additional fixtures above the norm can also increase the tank and/or drain field size required; examples include large volume bathtubs, laundry sinks, bidets, double toilets, etc. This is often when considered collectively for the whole household rather than individually.

*As indicated throughout this article, septic tank size recommendations are highly variable based on where you live, local government standards, underground soil type, house size and how much wastewater your specific home is expected to produce.

Minimum Septic Tank Capacity Table

See the following table for details on Minimum Septic Tank Capacity based on the number of residential bedrooms:

Number of BedroomsMinimum Septic Tank SizeMinimum Liquid Surface AreaDrainfield Size2 or less &#; Gallons27 Sq. Ft.800 &#; Sq. Ft. &#; Gallons27 Sq. Ft. &#; Sq. Ft. &#; Gallons34 Sq. Ft. &#; Sq. Ft. &#; Gallons40 Sq. Ft. &#; Sq. Ft. &#; Gallons47 Sq. Ft. &#; Sq. Ft.

Note the following regarding the table above:

• Minimum Liquid Surface Area, from the State of New York, refers to the surface area provided for the liquid by the tank&#;s width by length dimensions.
• Drainfield Size range is dependent on soil type. The drainfield recommendations given above are provided by the State of Michigan and can vary significantly based on local guidelines and area geography.

Additional Thought: Can a Septic Tank Be Too Big?

Without considering cost, a good question may be: &#;Can a septic tank be too big?&#;. The answer is no. As long as the septic tank is installed correctly, a septic tank cannot be too big, it can only be too small. By most recommendations, installing a larger size septic tank is often the safer, more preferred option. The reasons for this are:

1. A larger septic tank can accommodate for home usage fluctuations, such as with parties or long-term guests.
2. A larger septic tank can keep you from having to install a new tank if your family size increases or plan to make additions to your home such as extra bedrooms, bathrooms, plumbing fixtures, etc.

Takeaways | What Size Septic Tank Do I Need

The septic tank size recommendations presented here are recommendations only. They are based on compiled information from government and academic research. The exact septic tank size you need will vary on the variables outlined in this article. There is not a &#;one-size-fits-all&#; answer to the septic tank size for your specific home. There is a lot of variance based on where you live. Using the provided Minimum Septic Tank Capacity Table can give general insight into the septic tank and system size that may be best suited to your application and help estimate costs.

To find what size septic tank you need, know the size of your home and water-using features installed, then inquire with local government. Always check and verify with your state, city or local county&#;s department assigned to handle septic tanks, soil tests, and approvals prior to starting any septic tank installation job. This is often your local department of health.

If looking for a chart of tank sizes, check out our post on available septic tank volumes and size dimensions.

National Tank Outlet offers a wide selection of underground polyethylene septic tanks in both single chamber and double chamber in various styles, configurations and volumes.

For more information on conventional septic systems, consider this article from Texas A&M University for an overview of onsite wastewater treatment systems.

Understanding Septic Systems for Single-Toilet Setups: An Overview

A septic system for single-toilet setups is an on-site waste and wastewater treatment system, usually built for off-grid homes or small properties without access to centralized sewer systems. Its goal is to ensure a sanitary and safe toilet experience by effectively managing and treating domestic liquid waste within the confines of the property.

Septic tank installation for waste treatment

Septic tanks are more common than you may think &#; one in every four households in the US relies on a septic tank for waste management. The system can be eco-friendly when designed and maintained correctly. However, ensuring its legality involves compliance with local regulations and obtaining necessary building permits. You may have to consult local authorities and professionals to meet the environmental and legal standards requested in your area.

Mechanics of A Septic System: A Closer Look

A small septic system for one toilet comprises a septic tank and a drain field. If you decide to use more than one field, you&#;ll also need a distribution box that ensures that wastewater is divided equitably between them.

A small septic system for one toilet comprises a septic tank and a drain field.

• The small septic tank receives and holds the wastewater from the single toilet. Inside, heavy stuff sinks to the bottom and becomes sludge. Lighter stuff floats and creates scum, and what&#;s left in the middle is a clear liquid called effluent. The waste undergoes a natural treatment process facilitated by bacteria that break down organic matter.
• The drain field facilitates the final stage of treatment after the processing in the septic tank. The effluent is dispersed through perforated pipes and undergoes natural filtration because the soil is a biological filter, removing suspended solids and other impurities.

Advantages of Using Septic Tanks

• Small septic tanks are often more cost-effective than connecting to a centralized sewer system.
• Septic tanks eliminate the need for extensive infrastructure.
• Properly functioning septic systems can contribute to the natural treatment of wastewater.
• Septic tanks can accommodate various property sizes and soil types.
• The independence that comes with septic tanks can be advantageous in areas with unreliable or unavailable centralized services.
• Septic tanks generally require less energy than centralized treatment plants.
• Well-maintained septic systems are durable and can effectively manage human waste for many years.
• Vegetation in the drain field uses nutrients in the treated effluent, contributing to nutrient recycling and promoting plant growth.

Septic System for One Toilet: Guidelines and Size Considerations

1. Local regulations and permits

The company is the world’s best underground fiberglass water storage tanks supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

Most states delegate the issuance of construction and operating permits for septic tanks to local health departments. Some include water resource protection provisions to address potential impacts from nitrogen and phosphorus. The regulations also establish setback distances from buildings, driveways, property lines, and surface waters to prevent potential threats.

As part of most regulatory programs, local permitting agencies typically conduct site assessments to ensure that the ground adequately treats wastewater without endangering groundwater resources.

2. Septic tank size

The size of your septic tank will vary with the property size, estimated daily wastewater generation, and the number of occupants. For smaller homes with two rooms or less, a small septic tank size in the capacity range of 700 to 900 gallons is enough for adequate storage and treatment.

3. Types of small septic tanks 

Choosing the best septic tank will depend on local regulations, geographical conditions, and your budget. Concrete tanks are durable but may crack over time, while fiberglass tanks are lightweight and corrosion-resistant. On the other hand, a plastic septic tank is easy to install but may be less durable, and fiberglass-reinforced plastic (FRP) combines strength with corrosion resistance. Steel tanks, although strong, are less common due to rust and corrosion issues.

Plastic septic tanks

4. Installation

The process involves excavating the area, placing the tank, connecting the pipes, and setting up the drain field. Consider getting professional help to ensure adherence to design specifications and local regulations.

5. Routine maintenance

Schedule periodic pumping of the septic tank to remove accumulated sludge and scum. Also, routine inspections will help you identify any septic system issues before they become significant problems.

It&#;s wise to maintain detailed records of all maintenance activities, including pumping dates, inspections, and any repairs.

6. Other considerations

Since you opted for a small system, you must shift to water-efficient appliances and bathroom fixtures and fix any leaks as soon as they occur. These measures will avoid excessive water usage and reduce the overall load on the system.

Once your small septic system and pump are installed, you must develop emergency plans for unexpected events &#; such as system failures, heavy rain, or other extreme weather conditions. Write down the location of shut-off valves and always keep contacts for professional assistance on hand for emergencies.

Determining the Ideal Location for Your Small Septic Tank

The ideal location for your small septic tank depends on the following factors:

• Local regulations and zoning requirements: they provide clear limitations for setback distances from buildings, property lines, and water bodies
• Property characteristics: avoid placing the septic tank in low-lying areas prone to flooding
• Environmental considerations: the soil&#;s ability to absorb water will influence the location of the septic system
• Accessibility: you need an area with easy entry for service vehicles and routine maintenance activities
• Future landscaping: place the septic system away from deep-rooted plants

Alternatives to Septic Tanks for A Single Toilet 

• Aerobic treatment units (ATUs). They use oxygen to grow aerobic bacteria that treat wastewater. They&#;re more compact than traditional septic tanks and are suitable for areas with challenging soil requirements.
• Composting toilets. They break down organic waste into compost through natural processes. They are waterless or use minimal water, making them suitable for water conservation and off-grid living.

Composting public toilet. They are waterless or use minimal water, making them suitable for water conservation and off-grid living.

• Mound systems. They&#;re elevated beds of sand or gravel designed to treat and filter wastewater, ideal for areas with high water tables.
• Greywater systems. They capture and treat water from showers, sinks, and laundry, allowing it to be reused for non-potable purposes like irrigation.
• Biological filtration systems. They use biological processes and filtration media to treat wastewater. Examples include peat moss filters and biofilters.
• Anaerobic treatment units. They&#;re similar to septic systems but break down organic matter with anaerobic bacteria in sealed environments without oxygen.

HomeBiogas Eco-Toilet Solution

The HomeBiogas Bio-Toilet Kit is a modern alternative to traditional septic tanks. The kit includes a specialized toilet unit that connects with a biodigester and all the essential components necessary for effective waste management and step-by-step instructions for easy installation and maintenance. 

The HomeBiogas Bio-Toilet Kit is a modern alternative to traditional septic tanks.

The waste and wastewater go into the biodigester, where they undergo anaerobic digestion, producing biogas for cooking and nutrient-rich fertilizer.

Unlike traditional septic tanks that require extensive digging and installation processes, the HomeBiogas biodigester is easy to install and maintain, eliminating the need for complex ground excavation.

Another notable advantage is its adaptability to all geographical conditions. The HomeBiogas biodigester efficiently treats waste directly within its system. Furthermore, the booster kit can keep optimal temperatures in the biodigester throughout the year, ensuring reliable functionality in different weather conditions.

An environmentally friendly aspect of the HomeBiogas system is its minimal water requirement for operation. It cuts water bills and lowers water consumption, making it a sustainable choice for eco-conscious households.

Perhaps one of the most compelling advantages is the dual productivity of the system. Besides efficient waste treatment, the HomeBiogas solution allows users to collect biogas for cooking. Simultaneously, the biodigester produces nutrient-rich effluent from the waste, providing an eco-friendly resource for gardens and lawns.

Final Thoughts

Septic tanks function without extensive mechanical or chemical intervention. This advantage makes them a fascinating and environmentally conscious solution for decentralized wastewater treatment &#; perfect for off-grid, remote locations.

And, if you prefer not to dig extensively or use ample space for drain fields, a smaller system using composting toilets or a biogas digester can handle waste effectively off-grid.

If you want to learn more, please visit our website used cone bottom tank.