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Water: Class V Wells

Large-Capacity Septic Systems

This page will help you determine whether you have a large-capacity septic system, understand why large-capacity septic systems are regulated, learn how to comply with regulations for large-capacity septic systems, and find where you can go for help.

Who should read this page?
What is a septic system?
What is a large-capacity septic system?
What is not a large-capacity septic system?
Why does EPA regulate large-capacity septic systems?
What are the minimum federal requirements for large-capacity septic systems?
How is EPA helping to improve the performance of large-capacity septic systems?
Need help?


Who should read this page?

If you own or are interested in Large-Capacity Septic Systems (LCSSs), you may find the information useful. It explains the minimum federal requirements for LCSSs and how EPA is trying to improve their performance nationwide to protect our drinking water sources.

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What is a septic system?

A septic system is an on-site method of treating and disposing of sanitary wastewater. A typical septic system often consists of a buried tank that removes suspended solids from raw wastewater, an effluent distribution system and a soil absorption area where effluent undergoes additional treatment and attenuation through the processes of adsorption, dispersion, and biodegradation.

Septic systems are commonly found in rural and suburban areas where people often rely on ground water for their drinking water. Septic systems that are properly sited, designed, constructed, operated, and maintained pose little threat to drinking water sources. However, poorly designed, maintained, or operated septic systems can contaminate ground water or surface water. For more information on properly managed septic systems, visit EPA's Office of Wastewater Management's septic systems site.

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What is a large-capacity septic system?

A septic system is considered an LCSS if it receives solely sanitary waste either from multiple dwellings or from a non-residential establishment and the system has the capacity to serve 20 or more persons per day. In addition to the typical gravity-fed underground septic tank, effluent distribution system, and soil absorption area, LCSSs may have grease traps or other pre-treatment technologies, several small septic tanks, septic tanks that drain into a dry well, and connections to one large soil absorption system or multiple absorption areas that can be used on a rotating basis.

In general, LCSSs may be found serving the following facilities:

  • Apartment buildings
  • Trailer parks
  • Schools and religious institutions
  • Office, industrial, and commercial buildings
  • Shopping malls
  • State parks and campgrounds
  • Recreation or vehicle (RV) parks
  • Highway rest areas
  • Train and bus stations
  • Hotels and restaurants
  • Casinos

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Definitions

A well or injection well is a bored, drilled, or driven shaft, or a dug hole, whose depth is greater than its largest surface dimension; an improved sinkhole; or a subsurface fluid distribution system used to discharge fluids underground (40 CFR 144.3).

 

A Class V well is typically a shallow on-site disposal system used to place various non-hazardous fluids below the land surface (40 CFR 144.80).

 

Sanitary waste is liquid or solid waste originating solely from humans and human activities. This category includes waste collected from toilets, showers, wash basins, sinks used for cleaning domestic areas, sinks used for food preparation, clothes washing operations, and sinks or washing machines where food and beverage-serving dishes, glasses, and utensils are cleaned (40 CFR 144.3).


What is not a large-capacity septic system?

The disposal of industrial waste into septic systems can inhibit wastewater treatment and cause these systems to malfunction. More important, toxic chemicals can pass through these systems untreated, enter the ground water, and pose serious public health threats. To safeguard against this type of contamination, the Safe Drinking Water Act (SDWA) requires that EPA set minimum federal requirements to prevent the endangerment of underground sources of drinking water. A septic system that receives wastes other than sanitary waste is known as an industrial waste disposal well. A septic system that receives vehicular repair or maintenance waste is known as a motor vehicle waste disposal well. A covered pit that receives sanitary waste from multiple dwellings or a non-residential location and has the capacity to serve 20 or more persons per day is known as a large-capacity cesspool. As of 2000, new motor vehicles waste disposal wells and large-capacity cesspools are banned.

Here are links to more information about these kinds of wells:

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Why does EPA regulate large-capacity septic systems?

SDWA directs EPA to establish minimum federal requirements for state and tribal Underground Injection Control (UIC) Programs to protect underground sources of drinking water (USDWs) from contamination caused by injection activities (such as placing or discharging waste fluids underground). Protective requirements include the oversight of construction, operation, and closure of injection wells.

The UIC Program is designed to protect USDWs and provide safe and cost-effective means for industries, municipalities, and small businesses to dispose of their wastewater, extract mineral resources, and store water for the future. Illegal discharges have the potential to contaminate our drinking water resources. Preventing contamination of these resources protects the public and the economic health of communities nationwide.

States and tribes may apply to EPA for authority to administer the UIC Program. States and tribes that receive such authority must meet the minimum federal requirements; however, state and tribes can always adopt more stringent requirements.

The UIC Program regulates the shallow injection of non-hazardous fluids in a category called Class V wells. An LCSS is considered a type of Class V well. Visit the Well Types page to learn about other types of injection wells.

EPA does not regulate septic systems used by single-family homes or non-residential septic systems receiving solely sanitary waste that serve fewer than 20 persons per day. However, if these systems are improperly sited, operated or maintained they can threaten water quality. EPA has the authority to address malfunctioning systems on a case-by-case basis. States and local authorities may also have their own requirements to address these threats. Homeowners interested in learning more about single family septic systems can go to EPA's Office of Wastewater Management septic systems site.

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What are the minimum federal requirements for large-capacity septic systems?

The majority of Class V wells, including LCSSs, are "authorized by rule" provided they meet these minimum federal requirements:

  1. The owner or operator must submit basic inventory information (PDF) (3 pp, 69K, About PDF) to the permitting authority and
  2. The injectate cannot endanger USDWs.

In 1999, EPA published the Class V UIC Study of 23 categories of Class V wells including LCSSs. EPA undertook the national study to develop information to use in evaluating the risk these wells pose to USDWs and to determine whether additional federal regulations were warranted.

EPA concluded based on the Class V study that (1) the actual contamination from LCSSs is relatively isolated and (2) an additional layer of federal UIC requirements, placed on top of existing state and local LCSS regulations, would not be effective in further preventing endangerment from these wells.

EPA further concluded that LCSS requirements tailored to local conditions by state and local authorities, coupled with implementation of EPA's Voluntary Management Guidelinesis the most effective way to protect USDWs from contamination.

Existing federal regulations provide EPA and states with the authority to ensure that shallow injection wells are properly situated, constructed, operated, maintained, and (if necessary) closed in a manner that protects USDWs.


"Authorized by rule" means that an individual permit is not required. Local, state, or tribal rules governing these wells may be more stringent than the federal regulations. To determine the LCSS requirements in your state, check with your permitting authority. Inventory information includes facility name and location, owner/operator name and address, nature and type of injection well, and operating status. The second minimum federal requirement prohibits injection that allows the movement of fluids containing any contaminants (such as pathogens, solvents, or heavy metals) into a USDW if the presence of that contaminant may cause a violation of any primary drinking water regulation or adversely affect public health.

The "point of compliance" where LCSSs must meet the second minimum federal requirement is determined, case by case, depending on a variety of site-specific factors such as soil, hydrogeology, wastewater characteristics, and system design. Soil is an integral part of the design for an LCSS receiving solely sanitary waste and generally should be considered when determining the point of compliance. Attenuation occurs as the septic tank effluent travels through the soil below the drain field. Dissolved organic matter, pathogens, and some inorganic constituents can be attenuated in unsaturated soils below the drain field. If the LCSS is designed, operated, and maintained properly, it generally should not endanger USDWs. To find out who makes these decisions in your state, contact either the health department or permitting authority.

For more information on the technical aspects of on-site systems refer to:

How is EPA helping to improve the performance of large-capacity septic systems?

EPA is working with state and local health departments to ensure that the minimum federal requirements for Class V wells are met before an LCSS is permitted. In addition to educating owners and operators, EPA has a wide variety of tools and resources to assist state and local governments in improving the management and performance of septic systems. The cooperative relationship between EPA, states, and communities can ensure that all LCSSs are managed and regulated at the local level in a consistent way, regardless of size, and in a manner that protects drinking water sources.

In recognition of the unique relationship between tribal governments and EPA, the agency would like to develop with tribes partnerships similar to those it has with state and local health departments to address potential threats from LCSSs. EPA is gathering initial background information for use in developing a national perspective on tribal LCSSs. This information will be used to provide technical assistance so that tribes will be well equipped to address problems posed by these systems.

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Need help?

The links below provide contact information and additional information about septic systems.

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