Drinking water (SDWA)

Scope

The SDWA authorizes EPA to establish minimum standards to protect tap water and requires all owners or operators of public water systems to comply with these primary (health-related) standards. The 1996 amendments to SDWA require that EPA consider a detailed risk and cost assessment, and best available peer-reviewed science, when developing these standards. State governments, which can be approved to implement these rules for EPA, also encourage attainment of secondary standards (nuisance-related). Under the Act, EPA also establishes minimum standards for state programs to protect underground sources of drinking water from endangerment by underground injection of fluids.

Regulatory citations

• 40 CFR 141-149

Key definitions

• Action level: The concentration of lead or copper in water specified in 141.80(c) which determines, in some cases, the treatment requirements contained in subpart I of this part that a water system is required to complete.
• Aquifer: A geological formation, group of formations, or part of a formation that is capable of yielding a significant amount of water to a well or spring.
• Community water system: A public water system which serves at least 15 service connections used by year-round residents or regularly serves at least 25 year-round residents.
• Contaminant: Any physical, chemical, biological, or radiological substance or matter in water.
• Corrosion inhibitor: A substance capable of reducing the corrosivity of water toward metal plumbing materials, especially lead and copper, by forming a protective film on the interior surface of those materials.
• Direct filtration: A series of processes including coagulation and filtration but excluding sedimentation resulting in substantial particulate removal.
• Disinfectant: Any oxidant, including but not limited to chlorine, chlorine dioxide, chloramines, and ozone added to water in any part of the treatment or distribution process, that is intended to kill or inactivate pathogenic microorganisms.
• Disposal well: A well used for the disposal of waste into a subsurface stratum.
• Dose equivalent: The product of the absorbed dose from ionizing radiation and such factors as account for differences in biological effectiveness due to the type of radiation and its distribution in the body as specified by the International Commission on Radiological Units and Measurements (ICRU).
• Drywell: A well, other than an improved sinkhole or subsurface fluid distribution system, completed above the water table so that its bottom and sides are typically dry except when receiving fluids.
• Existing injection well: An injection well other than a new injection well.
• Filtration: A process for removing particulate matter from water by passage through porous media.
• Flocculation: A process to enhance agglomeration or collection of smaller floc particles into larger, more easily settleable particles through gentle stirring by hydraulic or mechanical means.
• Flow rate: The volume per time unit given to the flow of gases or other fluid substance which emerges from an orifice, pump, turbine or passes along a conduit or channel.
• Fluid: Material or substance which flows or moves whether in a semisolid, liquid, sludge, gas, or any other form or state.
• Generator: Any person, by site location, whose act or process produces hazardous waste identified or listed in 40 CFR Part 261.
• Ground water: Water below the land surface in a zone of saturation.
• Injection well: A well into which fluids are being injected.
• Injection zone: A geological formation, group of formations, or part of a formation receiving fluids through a well.
• Large water system: For the purpose of Subpart I of this part only, a water system that serves more than 50,000 persons.
• Lead service line: A service line made of lead which connects the water main to the building inlet and any lead pigtail, gooseneck or other fitting which is connected to such lead line.
• Legionella: A genus of bacteria, some species of which have caused a type of pneumonia called Legionnaires Disease.
• Maximum contaminant level: The maximum permissible level of a contaminant in water which is delivered to any user of a public water system.
• Maximum contaminant level goal (MCLG): The maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the health of persons would occur, and which allows an adequate margin of safety. Maximum contaminant level goals are non-enforceable health goals.
• Non-community water system: A public water system that is not a community water system. A non-community water system is either a “transient non-community water system (TWS)” or a “non-transient non-community water system (NTNCWS).”
• Plant intake: The works or structures at the head of a conduit through which water is diverted from a source (e.g., river or lake) into the treatment plant.
• Point of injection for Class V wells: The last accessible sampling point prior to waste fluids being released into the subsurface environment through a Class V injection well. For example, the point of injection of a Class V septic system might be the distribution box — the last accessible sampling point before the waste fluids drain into the underlying soils. For a dry well, it is likely to be the well bore itself.
• Point-of-use treatment device (POU): A treatment device applied to a single tap used for the purpose of reducing contaminants in drinking water at that one tap.
• Public water system PWS): A system for the provision to the public of water for human consumption through pipes or, after August 5, 1998, other constructed conveyances, if such system has at least fifteen service connections or regularly serves an average of at least twenty-five individuals daily at least 60 days out of the year. Such term includes: any collection, treatment, storage, and distribution facilities under control of the operator of such system and used primarily in connection with such system; and any collection or pretreatment storage facilities not under such control which are used primarily in connection with such system. Such term does not include any “special irrigation district.” A public water system is either a “community water system” or a “noncommunity water system.”
• SDWA: The Safe Drinking Water Act (Pub. L. 95-523, as amended by Pub. L. 95-190, 42 U.S.C. 300(f) et seq.).
• Sedimentation: A process for removal of solids before filtration by gravity or separation.
• Septic system: A well that is used to place sanitary waste below the surface and is typically comprised of a septic tank and subsurface fluid distribution system or disposal system.
• Small water system: For the purpose of Subpart I of this part only, a water system that serves 3,300 persons or fewer.
• Standard sample: The aliquot of finished drinking water that is examined for the presence of coliform bacteria.
• Subsidence: The lowering of the natural land surface in response to: Earth movements; lowering of fluid pressure; removal of underlying supporting material by mining or solution of solids, either artificially or from natural causes; compaction due to wetting; oxidation of organic matter in soils; or added load on the land surface.
• Supplier of water: Any person who owns or operates a public water system.
• Surface water: All water which is open to the atmosphere and subject to surface runoff.
• Too numerous to count: The total number of bacterial colonies exceeds 200 on a 47-mm diameter membrane filter used for coliform detection.
• Total Organic Carbon (TOC): Total organic carbon in mg/L measured using heat, oxygen, ultraviolet irradiation, chemical oxidants, or combinations of these oxidants that convert organic carbon to carbon dioxide, rounded to two significant figures.
• Total dissolved solids (TDS): The total dissolved (filterable) solids as determined by use of the method specified in 40 CFR Part 136.
• UIC: The Underground Injection Control program under Part C of the Safe Drinking Water Act, including an “approved program.”
• Underground injection: A well injection.
• Underground source of drinking water (USDW): An aquifer or its portion:
  • Which supplies any public water system; or
  • Which contains a sufficient quantity of ground water to supply a public water system; and
    • Currently supplies drinking water for human consumption; or
    • Contains fewer than 10,000 mg/l total dissolved solids; and
• Which is not an exempted aquifer.
• USDW: “Underground source of drinking water.”
• Well: A bored, drilled, or driven shaft whose depth is greater than the largest surface dimension; or, a dug hole whose depth is greater than the largest surface dimension; or, an improved sinkhole; or, a subsurface fluid distribution system.
• Well injection: The subsurface emplacement of fluids through a well.
• Well monitoring: The measurement, by on-site instruments or laboratory methods, of the quality of water in a well.
• Waterborne disease outbreak: The significant occurrence of acute infectious illness, epidemiologically associated with the ingestion of water from a public water system which is deficient in treatment, as determined by the appropriate local or State agency.
• Virus: A virus of fecal origin which is infectious to humans by waterborne transmission.

Summary of requirements

• If your business is considered to be a public water system:
  • Secure the services of a certified operator.
  • Submit required reports to your state and keep required records.
  • Conduct tests and monitoring for water quality and take steps to fix any identified issues.
  • Prevent well contamination.