Bedroom Gallons: Arizona's Septic Tank Rules In 2019

Arizona's diverse landscape, characterised by sprawling deserts and vibrant communities, presents unique challenges for managing wastewater. In rural communities, septic tanks are a necessity for healthy and sustainable waste disposal. Sizing a septic tank properly is crucial, as an undersized tank can lead to premature failure and costly repairs or replacements. The minimum septic tank capacity depends on several factors, including state, county and/or city guidelines, tank material, placement, soil conditions, and the expected volume of wastewater based on the size of the home.

Gallons per day (GPD)

For instance, a 4-bedroom home would have a GPD of 600, calculated as 4 bedrooms x 150 GPD. The septic tank size must then be double the daily GPD. So, for a 4-bedroom home with a GPD of 600, the recommended septic tank size is 1200 gallons. Similarly, a 5-bedroom home with a GPD of 750 would require a septic tank of at least 1500 gallons.

The minimum septic tank capacity requirements in Arizona are based on the number of bedrooms. For a 1- or 2-bedroom home, the minimum capacity is a 1000-gallon tank. A 3-bedroom home requires a minimum of a 1250-gallon tank, while a 4-bedroom home needs at least a 1500-gallon tank. For each additional bedroom beyond four, 250 gallons should be added to the septic tank capacity.

It is worth noting that these are the minimum requirements, and for optimal performance, experts often suggest going a size larger than the minimum. Larger tanks offer more capacity and extend the time between pump-outs. Other factors that can influence the recommended septic tank size include household water usage habits, the presence of a garbage disposal, jacuzzi tub, or whirlpool, and the soil percolation rate on the property. Consulting with an experienced septic professional is advisable to ensure the appropriate septic tank size for a specific home.

Septic tank sizing requirements

Sizing a septic tank correctly is crucial to avoid premature failure and costly repairs or replacements. The size of the septic tank is determined by several factors, including the specific type of septic system, local government regulations, ground geology, and the expected volume of wastewater.

In Arizona, the minimum septic tank capacity is determined by the number of bedrooms in the home. For optimal performance, it is often recommended to go a size larger than the minimum requirement. A larger tank means more capacity and longer times between needing to be pumped out.

• 1 or 2 bedrooms: 1,000-gallon tank
• 3 bedrooms: 1,250-gallon tank
• 4 bedrooms: 1,500-gallon tank
• Each additional bedroom over 4: Add 250 gallons

Other factors that can impact the recommended septic tank size include household water usage habits, the presence of a garbage disposal, the existence of a jacuzzi tub or whirlpool, and the soil percolation rate on the property.

It is important to note that these are just the minimum requirements, and bigger tanks are often preferred for their added capacity and reduced maintenance needs.

The size of the septic tank is also influenced by the specific type of septic system being used. There are several types of septic systems, including conventional, gravity-fed anaerobic systems, above-ground systems, recirculating sand or gravel filter systems, and bottomless sand filter systems. The specific system in place or planned for installation will impact the required tank size.

Local government regulations also play a significant role in determining septic tank size. These regulations vary widely across the United States due to differences in soil geographies and water features. Therefore, it is essential to check with local government regulations and guidelines to ensure compliance with size, placement, and material requirements.

Additionally, the underground soil type is a critical factor in determining septic tank size. A certified professional must perform a soil percolation evaluation, also known as a perc test, to assess the viability of the soil to handle and filter septic tank effluent properly.

In summary, determining the right septic tank size involves considering the number of bedrooms, local regulations, soil type, and expected wastewater volume. By taking these factors into account, homeowners can ensure they have a properly sized septic tank that meets their needs and complies with local requirements.

Local government regulations

In Arizona, the Arizona Department of Environmental Quality (ADEQ) is the primary authority responsible for enforcing regulations related to septic tanks. The ADEQ follows the Arizona Administrative Code (AAC) R18-9-A314, which covers on-site wastewater treatment facilities, commonly known as septic tank systems. These regulations encompass system design, permitting, installation, maintenance, and inspections.

When installing a septic tank in Arizona, permits are required, and specific forms must be submitted to the ADEQ or the county health department. A soil evaluation is also necessary, and careful planning and understanding of the system design are essential. While self-installation is allowed, many homeowners opt for professional installation to ensure compliance with all regulations.

The minimum septic tank capacity requirements in Arizona are based on the number of bedrooms in the home. For a 1 or 2-bedroom house, the minimum capacity is a 1,000-gallon tank. For a 3-bedroom house, the minimum capacity increases to 1,250 gallons. A 4-bedroom house requires a minimum of a 1,500-gallon tank, and for each additional bedroom over 4, 250 gallons should be added. These are the minimum sizes, and experts often recommend opting for a larger tank for optimal performance and longer intervals between pumping.

Other factors that can impact the recommended septic tank size in Arizona include household water usage habits, the presence of a garbage disposal, the existence of a jacuzzi tub or whirlpool, and the soil percolation rate on the property. Consulting with an experienced septic professional can help determine the most suitable septic tank size for a specific home.

Soil percolation rate

The soil percolation rate is a critical factor in determining the design and functionality of a septic system. Percolation refers to the rate at which water moves through the soil, and this has a direct impact on the effectiveness of wastewater treatment in septic systems.

In Arizona, the percolation rate is a key consideration in the installation of septic tanks, especially in rural areas where there is no access to public sewer systems. The Arizona Department of Environmental Quality (ADEQ) enforces strict regulations on on-site wastewater treatment facilities, commonly known as septic tank systems.

The percolation rate is determined through a soil percolation evaluation, often referred to as a perc test. This test assesses how viable the underground soil is to handle and filter septic tank effluent. The results of this test will determine if a specific location is suitable for a septic tank and what type of system is required.

The perc test measures the time it takes for water to drop a certain distance in a saturated hole. If it takes less than 5 minutes for the water to drop by 1 inch, the effluent will move too quickly for proper treatment, as is often the case with sandy soils.

In Arizona, the nominal Soil Absorption Rate (SAR) is based on qualitative soil analysis and/or percolation tests. Each major soil band can have a different SAR, and the overall SAR may be a weighted average of the individual SARs if horizontal dispersal is assumed. However, if downward dispersal is assumed, the most limiting SAR will be chosen.

The SAR is then used to determine the Minimum Vertical Separation (MVS), which is the allowable distance from the bottom of the constructed drainfield to the top of the nearest limiting subsurface condition. Higher treatment levels that result in lower biochemical oxygen demand (BOD) and suspended solids (SS) can lead to higher allowable SAR values and a reduced total absorption area.

The percolation rate of the soil is just one factor in designing a septic system. Other considerations include the number of bedrooms, plumbing fixtures, and water-using features in the home, as well as local government regulations and the expected volume of wastewater.

In summary, the soil percolation rate plays a crucial role in determining the design and functionality of a septic system in Arizona. The perc test helps to evaluate the viability of the soil for wastewater treatment and informs the choice of septic system type and size. By considering the percolation rate along with other factors, homeowners can ensure that their septic system is efficient, compliant with regulations, and environmentally friendly.

Septic tank installation

Installing a septic tank in Arizona requires careful planning and consideration of various factors. Here is a comprehensive guide to help you through the process:

Understanding Septic Tank Sizing in Arizona:

Firstly, it's important to understand that septic tank sizing requirements in Arizona are typically based on the number of bedrooms in a home. The minimum capacity requirements are as follows:

• 1 or 2 bedrooms: 1,000-gallon tank
• 3 bedrooms: 1,250-gallon tank
• 4 bedrooms: 1,500-gallon tank
• Each additional bedroom over 4: Add 250 gallons

Other Factors Influencing Septic Tank Size:

Apart from the number of bedrooms, other factors can impact the recommended septic tank size:

• Household water usage habits
• Presence of a garbage disposal unit
• Existence of a jacuzzi tub or whirlpool
• Soil percolation rate on your property

Choosing the Right Septic System:

There are several types of septic systems available, and the chosen system will impact the required tank size. The most common type is the conventional, gravity-fed anaerobic system. However, other options include above-ground septic systems, recirculating sand or gravel filter systems, and bottomless sand filter systems.

Complying with Local Regulations:

It is crucial to adhere to local government regulations when installing a septic tank. In Arizona, the Arizona Department of Environmental Quality (ADEQ) is the primary authority for septic tank regulations. They enforce the Arizona Administrative Code (AAC) R18-9-A314, which covers on-site wastewater treatment facilities, including septic tank systems. Make sure to obtain the necessary permits from the ADEQ or the local county health department before starting any installation work.

Site Evaluation and Soil Considerations:

A site evaluation is essential to determine the suitability of a conventional septic system for your property. This evaluation considers factors such as soil conditions, absorption rates, subsurface characteristics, and setback requirements. Arizona regulations require a registered professional engineer, geologist, sanitarian, or licensed septic/plumbing contractor to perform this evaluation. Additionally, the underground soil type plays a critical role in system effectiveness and septic tank size. A certified professional must conduct a soil percolation evaluation (perc test) to assess the viability of the soil for handling and filtering septic tank effluent.

Installation Process:

The installation process for a septic tank can be complex and demanding. While it is legal to install your own septic tank in Arizona, many homeowners opt for professional installation to ensure compliance with regulations and system efficiency. The installation must adhere to approved design plans, manufacturer guidelines, and construction best practices.

Maintenance and Pumping:

Regular maintenance of your septic tank is crucial to keep it functioning correctly. This includes pumping and cleaning filters, baffles, and filters to prevent clogs and maintain proper effluent flow. For a typical 3-bedroom home, experts recommend pumping the septic tank every 3 to 5 years, with more frequent pumping for larger households.

Frequently asked questions