How Deep Do You Dig A Hole For 500 Gallon Septic Tank? (Solution)

500-gallon propane tank As such, it requires an excavated hole of around 12 feet in length, 5 feet in width, and 6 feet in depth.

  • A 500-gallon tank measures around: 9 feet, 10 inches in length, 5 feet in height As such, it requires an excavated hole of around 12 feet in length, 5 feet in width, and 6 feet in depth.

How deep should septic tank be buried?

In most cases, septic tank components including the lid, are buried between 4 inches and 4 feet underground. You can use a metal probe to locate its edges and mark the perimeter. If you do not find the lid by probing, shallow excavation with a shovel along the tank’s perimeter should reveal the lid.

How deep is a septic pit?

Seepage pits typically are 5-7 ft in diameter, and depending on soil condition anywhere between 15-40 feet deep. The actual walls of the pit are only 4′ in diameter, and the surrounding area is filled with gravel.

How deep are drain fields buried?

A typical drainfield trench is 18 to 30 inches in depth, with a maximum soil cover over the disposal field of 36 inches.

How do you find a buried septic tank?

Tips for locating your septic tank

  1. If the septic tank lid is underground, you can use a metal detector to locate it.
  2. You can use a flushable transmitter that is flushed in the toilet and then the transmitter is tracked with a receiver.

Is a 500 gallon septic tank big enough?

The minimum tank size for a three bedroom house is 1200 gallons. 500 or 750 gallon tanks used to be quite common in old houses, but they are not large enough for modern households, and are from a time without automatic washers, large spa tub, dishwashers, or multiple daily showers.

What are the dimensions of a 500 gallon concrete septic tank?

500 Gallon Siphon Tank Package Overall Length: 79” Overall Width: 48” Height to center line of inlet: 48” Height to center line of outlet: 48”

What size septic tank do I need for a tiny house?

Tiny homes typically require a 500 to 1,000-gallon septic tank. Though, it’s not always possible to implement a tank of this size. In some states, for example, the minimum tank size is 1,000 gallons. There may be exceptions to this rule if your home is on wheels.

How many Infiltrator chambers do I need?

As a general rule, trenches ‘fingers’ should be no longer than fifty feet ( 12 or 13 Infiltrators long ) for best function and most even effluent distribution. Unless you are installing as a “bed” system (where the chambers are right next to each other), leave at least six feet of undisturbed soil between fingers.

What is the minimum depth of a sewer line?

On average, trenches should be around 12-24 inches-deep, and wide enough to house your pipe comfortably before filling it in with soil and sod. As we’ve mentioned, in cold weather regions, this will need to be deeper or you’ll have problems with your sewage freezing.

What should be the size of septic tank?

Length of septic tank (L) should be taken as 9feet 9 inches or 9.75 feet. Breadth of septic tank (B) should be taken as 6 feet 3 inches or 6.25 feet. The standard height (D) of septic tank should be taken as 5 feet 9 inches or 5.75 feet.

How many lids are on a septic tank?

A septic tank installed before 1975 will have a single 24-inch concrete lid in the center of the rectangle. A two-compartment tank installed after 1975 will have two lids of either fiberglass or polyethylene, centered at opposite ends of the rectangle.

Septic Tank Design Depth – how deep should the septic tank be located

  • When establishing a septic tank, you may ask a QUESTION or make a COMMENT regarding how deep the septic tank should be located.

InspectAPedia does not allow any form of conflict of interest. The sponsors, goods, and services described on this website are not affiliated with us in any way. Design depth for a septic tank: What are the most frequent depths to which septic tanks, cesspools, seepage pits, and drywells are buried? Is it necessary to locate the septic tank below the frost line in order to prevent it from freezing? Septic tanks are placed at a certain depth, and there are various elements that impact the actual depth to which a septic tank (or cesspool, drywell, or soak-pit) will be sunk, which are discussed below.

For this topic, we also have anARTICLE INDEX available, or you may check the top or bottom of the page.

Septic Tank Installation Depth

Table of Contents for the Article Series

  • SEPTIC TANK DESIGN DEPTH- this article

How Deep Should WePutthe Septic Tank at Original Installation?

Septic tanks may be built almost anywhere in the soil, regardless of its depth. When operating in a freezing climate, even in uninhabited homes, it is unlikely that the septic tank serving an occupied home or even an unoccupied one will freeze. This is due in part to latent heat received by the septic tank’s bottom from earth, in part to heat generated by bacteria in the septic tank, and in part to warm wastewater entering from a building served by the septic system, and in part to warm wastewater entering from the building served by the septic system.

You’ll kill the bacteria, damage the drainfield, and taint the surrounding ecosystem as a result of this.

Factors Determining Septic Tank Depth

The following are the primary elements that influence the actual depth at which a septic tank is likely to be buried (and, consequently, the depth to which you may have to dig to locate the septic tank) at a specific site:

  • The depth to which the lowest sewage line departs the structure that the septic tank serves is referred to as the sewer line depth. Given that we often rely on gravity to transport sewage from a building to a septic tank, the tank will be lower than the waste line that exits the building that it serves. a spot where the contractor discovered site characteristics suited for burying a septic tank because of its form, rocks, and impediments If a location has bedrock or huge rocks that are near to the surface, the tank may be relocated
  • The greater the distance between the tank and the structure, and the greater the depth of the tank if the system relies on gravity to carry sewage, the deeper the tank will be. We don’t place septic tanks any deeper than they need to be since we are normally transporting effluent from the septic tank to the drainfield by gravity as well as by pumping it out. Plumbers often build sewage lines to slope down from the inlet to the outlet at a rate of 1/8″ per foot to 1/4″ per foot of linear run of the waste pipe, depending on the kind of waste pipe. In order to avoid septic drainfield burial at an excessive depth, we must ensure that there is sufficient air in the soil, since the absence of oxygen deep in the soil will inhibit certain desired bacterial action (the aerobic bacteria) that is required to break down and process sewage. It is certainly possible to locate and position the septic tank anywhere, including uphill from the building, if a sewer ejector pump or grinder pump system is utilized to transport sewage from a structure to an underground storage tank. If a sewage effluent pump is used to transport septic effluent from the septic tank to the drainfield, we may, of course, locate the tank “downhill” from the drainfield as well
  • But, if a sewage effluent pump is not utilized, we cannot. Growing grass: If the septic tank is just 2 or 3 inches below the surface of the earth, you might as well have left the top of the tank visible, because grass will not grow in such thin soil as you would expect. Adding 6″ to 12″ of backfill may be sufficient to allow grass to grow over the septic system
  • However, this is a purely aesthetic issue and does not affect the system’s functionality. See SEPTIC SYSTEMS, OVERHAULED PLANTS
  • Recommendations from the manufacturer: Some modern septic treatment system designs need the use of a skilled system operator to perform highly specified inspection and maintenance intervals. According to the information provided atBAT MEDIA SEPTIC PLANTS, BAT septic systems (biologically accelerated treatment) are maintained or examined at 6-month intervals, among other things. According to the maker of that technology (Jet Inc.), it is extremely critical that the finishing grade slope away from the facility when completed. In addition, the grade must be at least 1″ below the bottom of the access covers to be considered. (Jet retired in 2016)
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A service riser should be put in deep septic tanks to provide access to the tank. Plungers are large-diameter “wells” that are installed over the entrance and/or outlet ports of a septic tank in order to provide simple access for tank pumping, inspection, and baffle repair. Plungers are also used for septic tank pumping, inspection, and baffle repair. If the septic tank is sunk more than a few inches below the surface of the earth, good practice calls for the installation of a septic riser, which is a high diameter pipe that allows for easy access to the septic tank for inspection and cleaning.

Continue reading atSEPTIC TANK DEPTH to learn how to determine the depth of a septic tank’s cover, or choose a topic from the closely-related articles listed below, or see the completeARTICLE INDEX for more information.

Alternatively, view the FAQs on SEPTIC TANK DESIGN DEPTH – questions and answers that were originally posted on this page. Alternatively, consider the following:

Septic Tank Articles

  • The following topics are covered: SEPTIC DRAINFIELD LOCATION
  • SEP

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Septic Tank Installation Guidelines

Each and every tank built by Glacier Precast Concrete has through a thorough inspection and testing process at the factory. It is vital that each tank is installed correctly in order for it to work effectively and remain watertight. Correct installation techniques may prevent many of the issues that arise in the functioning of tanks, such as tanks leaking (either water flowing into or out of them) and system failure before they have a chance to occur. Improper installation procedures can cause significant damage to the tank, as well as serious physical injury to those working on it.

It should also be beneficial to designers, building inspectors, and homeowners in general.


PLAN YOUR NEXT PROJECT. To properly prepare the sub-bed elevation and allow the tank to properly receive the sewer pipe that is coming from the home or building, you will need to know the invert elevation (which is the measurement from underside of the tank to bottom of the tank’s inlet opening). You can find this information on the tank’s invert elevation page. For these crucial measurements, see the manufacturer’s most recent literature or website, or call us at 406-752-7163 for assistance.

Take into consideration the fact that the site where the tank will be installed must be accessible by large and highly laden vehicles with a maximum weight of up to 80,000 pounds.

It must be removed of all trees and branches, big boulders, overhead wires, underground utilities, and other structures that might be damaged or interfere with the delivery and unloading of the septic tank, as well as any other structures that could interfere with or be harmed by the septic tank.

If any damage occurs to the work site, the delivery vehicle, or the tank, the purchaser/installer is liable.

As a result, it is critical to provide appropriate access for delivery equipment to reach the excavation and remove the tank from the truck.

Standard concrete septic tanks are not built to withstand severe traffic loads or to transport any type of heavy equipment. Because of this, it is recommended that a dedicated tank be installed to handle high traffic loads or unique scenarios. Please inquire if you require any of these.


All underground utilities should be identified and found BEFORE YOU DIG! This is for the safety of your backhoe (excavator) operator as well as the general public’s benefit. The recommended technique is as follows: To identify the dig site, you must file a locate request by dialing 811 at least 24 hours before you want to begin digging. More information may be found on the following website: Location Center in the Subterranean Space (UULC) Toll-free number: 1-800-424-5555 (or 811) Area of Coverage: All of MontanaUULC will call the impacted utilities, who will either send someone to mark their subterranean lines or notify you if their underground services will not be affected by your intended dig, depending on the situation.

  • Prepare the hole so that it is at least 18″ bigger than the tank, to provide for adequate area to compact the backfill material appropriately.
  • It is important to slant excavation walls for the sake of stability and worker safety.
  • Over a thoroughly compacted and uniformly level basis, a layer of pea gravel or sand of 5-6″ minimum is recommended overlaying the foundation.
  • Tanks will be harmed if they are allowed to bear down on huge stones, rocks, or cliff edges, for example.

Tank Placement

The first step after receiving your new tank is to check it while it is still on the truck to ensure that you have gotten the tank that is appropriately designed and proportioned according to your specifications. Any inconsistencies should be noted to the driver, who should then cross-check the tank with the Bill of Lading or Sales Order to ensure that everything is in order. Second, check the tank for any possible damage that may have occurred during the transportation process. Prior to installation, it is important to establish that the tank’s orientation is such that the input ports face the dwelling and the discharge outlets face the drain field or treatment facility.

Check to see that the pitch of the input pipe leading from the home to the tank complies with local regulations.

The suitable equipment or special lifting device will be used to ensure that it is handled appropriately and safely. In accordance with industry policy, “all personnel should be kept away from loads that are going to be hoisted and from hanging loads” (OSHA Rule29 CFR 1901-184 -9)


When backfilling, extreme caution should be exercised to avoid damaging or misaligning the entrance and exit pipes, the tank and fittings, and any other pipe joints. Ideally, backfill should be deposited in layers of less than 12″ thickness that are mechanically compacted and homogeneous in appearance. It is not necessary to backfill and compress one or two sides before backfilling and compacting the opposing sides. In most cases, excavated material may be utilized for backfill, but it should not contain any huge stones or boulders.

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Even concrete tanks, on the other hand, can float if the water level surrounding them increases to a sufficient level.

This aids in keeping the tank in place and offers some protection against the tank being damaged during the compaction process.

Tanks that will be installed at a depth greater than this will require special traffic-rated lids to be installed.


Please do not get inside the tank! Gases that are dangerous in enclosed environments can be found there. Only properly qualified professionals with the appropriate tests and protective equipment should contemplate entering a tank, and they should never do it by themselves.


Generally, the number of bedrooms in a house and the amount of water that percolates through the soil on the subject land define the size of the septic system and tank required. When designing a septic system, keep in mind the possibility of future expansion requirements. If a septic system is overwhelmed, it will not be able to perform its functions correctly. A guarantee will not be provided for tanks that are under capacity or that have not been properly sized and fitted. Glacier Precast Concrete suggests that the tank capacity (septic chamber) be raised by 500 gallons if the owner has installed or plans to install a waste disposal (grinder) or if the owner anticipates doing so in the future.

In addition, it is critical that all entrance and exit pipework be linked using flexible compression fittings that are compliant with ASTM C 1227 and C 923 standards and specifications.

MPCA staffer bites bullet, pulls “trigger” on new septic system

Barb McCarthy of the MPCA, like many other people who are looking to sell their home or lake property, wanted to have her septic system tested and given a clean bill of health before her home could be sold this past summer before it could be transferred. A number of Minnesota counties have implemented a variety of “triggers” in order to detect , upgrade or replace septic systems that do not meet current safety and performance criteria. Nevertheless, McCarthy, who works in the MPCA Subsurface Sewage Treatment System (SSTS) program, claims that she “didn’t even bother with an examination” since she knows what she knows about the soils in her neighborhood.

Louis County, I was aware that my old system would not be able to fulfill criteria (near Duluth).

They went to McCarthy’s farm as well as a few other locations in the Duluth area to dig pits and evaluate the soil profiles that emerged.

McCarthy’s property’s soil pit revealed around six to eight inches of soil ideal for a septic system drainfield and several feet of red clay that was largely impermeable to rain and snow (see photo below).

Getting the right “profile”

Water must pass through at least 36 inches of sufficient existing soil or other filter media, such as sand, in order to receive effective treatment. The wastewater must move at precisely the proper pace, and not too fast or too sluggish. A minimum of three feet of separation must also exist between the point where wastewater enters the treatment field and the seasonal high water table (the level at which soil is inundated during the wettest period of the year) in order to prevent ground water contamination.

  • Septic professionals must first dig a hole to examine the soil characteristics (soil profile and distance from seasonally flooded soils) and then present the homeowner with design alternatives that would be appropriate for that particular site before creating a septic system for them.
  • In some instances, the soil profile is such that a drainfield can be constructed quite simply.
  • An in-ground trench system is what this is referred to as.
  • McCarthy’s house was unquestionably in need of a mound system of some sort.

Building the mound

To find an appropriate place for her mound system, McCarthy collaborated with her septic system designer and installer to design and build a system that would service the home’s 2,100 square foot, three-bedroom layout. A large number of trees had to be removed in order to create way for the mound. Furthermore, because the current acceptable soil layer in her yard is only six inches thick at its weakest point, the mound required 30 to 32 inches of washed sand to be properly constructed and stabilized.

  • On top of the sand lies a rock bed that is 5 feet by 85 feet in dimensions (see photo above).
  • Fine debris must be removed from the rocks in order to prevent them from being washed down into the sand, where they might clog the system and cause it to fail.
  • Installed on top of the rock is a network of perforated wastewater distribution pipes.
  • Topsoil and sand are prevented from entering the rock bed by an unique fabric material that enables air and water to pass through while keeping topsoil and sand out.
  • Combined septic tank/pump tank: Liquid and solid waste created by sinks, bathtubs, showers, and toilets is conveyed from the home to the tank by an underground conduit known as a “building sewer” (above).
  • According to McCarthy’s design, the system will purify 300 gallons of wastewater each day and transport it to the mound through a supply pipe (pictured above).
  • Having a period of time between dosages gives the wastewater enough time to successfully travel through the mound sand and into the underlying soil.
  • When the tank level drops to a specific level, it will shut off until the pump tank fills back up to that level and another dosage is sent to the mound.

If a pump fails to shut off, any residual water in the supply line flows back into the pump tank, keeping water in the pipe from freezing during the winter months.

Insulation important for new septic systems

McCarthy’s mound measured 125 feet long and 40 feet broad when it was done, at a cost of more than $15,000. As McCarthy points out, “when you average the cost of the system over its estimated lifetime of 30 years or more, you come up with a value that is not that different from what folks who live in metropolitan areas pay for their wastewater treatment.” The major difference between the cost of a rural septic system and the cost of a city septic system is that the investment is paid up front, which can present a barrier for some homeowners if they are not able to recuperate part or all of the cost via a home sale.

The large dimensions of the mound are required on this site to ensure that the effluent is able to move through it at the proper rate and in a manner that does not allow the effluent to surface at the “toe” or downslope berm of the mound, which is necessary to keep the sewage below the surface of the ground.

Plants such as grass and other cover crops are crucial because they assist to provide insulation, which will aid in the prevention of freezing difficulties, particularly during the first winter after the building of the system.

She also expects that there will be snow cover this year, which will provide as extra insulation for the house.

Septic Tank Installation and Replacement Cost

The typical cost in the United States ranges from $500 to $5,000. The national average cost of a septic tank installation or the cost of replacing an outdated septic system is dependent on a number of different variables.

Septic Tank Installation Average Costs
National Minimum Cost $500
National Maximum Cost $5000
National Average Cost $1500

According to the Environmental Protection Agency, one in every five residences in the United States relies on a septic system for wastewater management (EPA). In the case of septic systems, you may have a septic system for your home alone, or you may be connected to a communal system that services a small number of homes. Untreated wastewater created by a house or company is treated on site by a septic system, which is an on-site treatment system. Sewage lines convey wastewater from your shower, toilet, sinks, clothes washer, and trash disposal away from your home and into a septic tank buried in your yard.

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Solids are separated from floatable debris in the septic tank, and the leftover liquid drains from the tank through a series of perforated tubes and onto a drain field or leach field after being separated in the tank.

The usage of septic systems is popular in rural regions that do not have access to a centralized municipal sewer system.

Tank capacity ranges from less than 1,000 gallons to more than 2,000 gallons, with the size of the tank determined by the quantity of water you consume on a daily basis.

Condos, apartments, residences, business spaces, and other types of structures might benefit from septic system installation or replacement services.

What’s in this cost guide?

  • Soil type
  • Tank size and kind
  • Equipment
  • Installation
  • Maintenance
  • Lift station
  • And more. Septic systems that are not conventional
  • How septic tanks function
  • Signs that you need to upgrade your system
  • How to employ a professional

Alternative septic systems

Alternative techniques are particularly effective on steep locations, highly rocky land, or poor soil. Among the options available are aerobic septic systems, mound septic systems, raised-bed septic systems, and others. The cost of a septic system installation or replacement may be greater or cheaper than the average depending on the area and kind of system. Locate the most qualified septic system consultant for your project needs. Zip code must be entered correctly.

Signs you need a new system

Anyone would not want sewage water rising up through their front yard on one of the hottest days of the summer season (or even on the coldest day of winter). Waterborne pathogens such as protozoa, bacteria (such as E. coli), and viruses may be spread through fecal matter, making wastewater not just stinking and disgusting, but also potentially deadly. It is possible for unclean wastewater to drain through the soil and pollute the water you and your friends and neighbors drink if your septic system is leaky, overwhelmed, or otherwise compromised.

Knowing what indicators to look for might help you catch an issue before it becomes a major problem.

This includes having your septic tank pumped out by a professional every three to five years.

Other indicators may indicate that it is necessary to contact a septic system specialist as soon as possible to either repair or replace the system.

What size of septic tank do I need?

Probably one of the last things on your mind when you are constructing a new house is the location of your septic system. After all, shopping for tanks isn’t nearly as entertaining as shopping for cabinetry, appliances, and floor coverings. Although you would never brag about it, your guests will be aware if you do not have the proper septic tank placed in your home or business.

septic tanks for new home construction

The exact size of the septic tank is determined mostly by the square footage of the house and the number of people who will be living in it. The majority of home septic tanks have capacities ranging from 750 to 1,250 gallons. A 1000 gallon tank will most likely be required for a typical 3-bedroom home that is smaller than 2500 square feet in size. Of course, all of this is dependent on the number of people who live in the house as well as the amount of water and waste that will be disposed of through the plumbing system.

For the most accurate assessment of your septic tank needs, you should speak with an experienced and trustworthy sewer business representative. They can assist you in planning the intricacies of your septic system, including which sort of septic system will be most beneficial to you.

planning your drainfield

Here are some helpful hints for deciding where to locate your drainfield when you’re designing it.

  • Vehicles should not be allowed on or around the drainfield. Planting trees or anything else with deep roots along the bed of the drain field is not recommended. The roots jam the pipes on a regular basis. Downspouts and sump pumps should not be discharged into the septic system. Do not tamper with or change natural drainage features without first researching and evaluating the consequences of your actions on the drainage field. Do not construct extensions on top of the drain field or cover it with concrete, asphalt, or other materials. Create easy access to your septic tank cover by placing it near the entrance. Easy maintenance and inspection are made possible as a result. To aid with evaporation and erosion prevention, plant grass in the area.

a home addition may mean a new septic tank

Do not make any big additions or renovations to your house or company until you have had the size of your septic system assessed. If you want to build a house addition that is more than 10% of your total floor space, increases the number of rooms, or necessitates the installation of new plumbing, you will almost certainly need to expand your septic tank.

  • For a home addition that will result in increased use of your septic system, your local health department will require a letter from you that has been signed and authorized by a representative of your local health department confirming that your new septic system is capable of accommodating the increase in wastewater. It is not recommended that you replace your septic system without the assistance of a certified and competent contractor.

how to maintain your new septic system

Septic tank cleaning and septic tank pumping services are provided by Norway Septic Inc., a service-oriented company devoted to delivering outstanding septic tank cleaning and septic tank pumping services to households and business owners throughout the Michiana area. “We take great delight in finishing the task that others have left unfinished.” “They pump, we clean!” says our company’s motto. Septic systems are something we are familiar with from our 40 years of expertise, and we propose the following:

  • Make use of the services of a qualified specialist to develop a maintenance strategy. Make an appointment for an annual examination of your septic system. Utilize the services of an effluent filter to limit the amount of particles that exit the tank, so extending the life of your septic system. Waste items should be disposed of properly, and energy-efficient appliances should be used. Make sure you get your septic system professionally cleaned every 2 to 3 years, or more frequently if necessary, by an experienced and qualified expert
  • If you have any reason to believe that there is an issue with your system, contact a professional. It is far preferable to catch anything early than than pay the price later. Maintain a record of all septic system repairs, inspections, and other activities

common septic questions

Here are some of the most frequently asked questions by our septic customers.

How do I determine the size of my septic tank?

If you have a rectangular tank, multiply the inner height by the length to get the overall height of the tank. In order to find out how many gallons your septic tank contains, divide the number by.1337.1337

How many bedrooms does a 500-gallon septic tank support?

The exact size of the septic tank is determined mostly by the square footage of the house and the number of people who will be living in it. The majority of home septic tanks have capacities ranging from 750 to 1,250 gallons. A 1000 gallon tank will most likely be required for a typical 3-bedroom home that is smaller than 2500 square feet in size.

How deep in the ground is a septic tank?

Your septic system is normally buried between four inches and four feet underground, depending on the climate.

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