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Document ID us-sss-2026-04-06 Title Septic Systems (Decentralized/Onsite Systems) URL https://www.epa.gov/septic Jurisdiction /us Subdomain(s) none Language Status completed Analyzed at 2026-05-12 04:41:48.190097+00:00 Relevance inventory_targeted_fetch

Q Qualitative Requirements (0)

No qualitative requirements.

P Quantitative Requirements (0)

No quantitative requirements.

D Definitions (42)

Req ID Category Name Context Confidence
#D001urbanized areasurban areas with a population of at least 50,000high
#D002BMPsBest Management Practiceshigh
#D003MS4An MS4 is a conveyance or system of conveyances that is: owned by a state, city, town, village, or other public entity that discharges to waters of the U.S., designed or used to collect or convey stormwater (e.g., storm drains, pipes, ditches), not a combined sewer, and not part of a sewage treatment plant, or publicly owned treatment works (POTW).high
#D004POTWpublicly owned treatment workshigh
#D005SWMPsstormwater management programshigh
#D006NPDESNational Pollutant Discharge Elimination Systemhigh
#D007MSGPMulti-Sector General Permithigh
#D008Category One (i)Facilities subject to federal stormwater effluent discharge standards at 40 CFR Parts 405-471high
#D009Category Two (ii)Heavy manufacturing (e.g., paper mills, chemical plants, petroleum refineries, steel mills and foundries)high
#D010Category Three (iii)Coal and mineral mining and oil and gas exploration and processinghigh
#D011Category Four (iv)Hazardous waste treatment, storage, and disposal facilitieshigh
#D012Category Five (v)Landfills, land application sites, and open dumps with industrial wasteshigh
#D013Category Six (vi)Metal scrapyards, salvage yards, automobile junkyards, and battery reclaimershigh
#D014Category Seven (vii)Steam electric power generating plantshigh
#D015Category Eight (viii)Transportation facilities that have vehicle maintenance, equipment cleaning, or airport deicing operationshigh
#D016Category Nine (ix)Treatment works treating domestic sewage with a design flow of 1 million gallons a day or morehigh
#D017Category Ten (x)Construction sites that disturb 5 acres or morehigh
#D018Category Eleven (xi)Light manufacturing (e.g., food processing, printing and publishing, electronic and other electrical equipment manufacturing, public warehousing and storage)high
#D019Pretreatment standardspollutant discharge limits which apply to industrial users (IUIUA source of indirect discharge. [40 CFR 403.3(j)]s).high
#D020Pretreatment requirementssubstantive or procedural requirements applied to IUs.high
#D021IUindustrial usershigh
#D022Local limitssite-specific and can be numeric or narrative effluent discharge limits, including BMPs.high
#D023pass throughA discharge that exits the POTW into waters of the United States in quantities or concentrations that, alone or in conjunction with a discharge or discharges from other sources, is a cause of a violation of any requirement of the POTW's NPDES permit (including an increase in the magnitude or duration of a violation). [40 CFR 403.3(p)]high
#D024interfereA discharge that, alone or in conjunction with a discharge or discharges from other sources, both (1) inhibits or disrupts the POTW, its treatment processes or operations, or its sludge processes, use, or disposal; and (2) therefore is a cause of a violation of any requirement of the POTW's NPDES permit (including an increase in the magnitude or duration of a violation) or of the prevention of sewage sludge use or disposal in compliance with ... [applicable] statutory provisions and regulations or permits issued thereunder (or more stringent state or local regulations). [paraphrased from 40 CFR 403.3(k)]high
#D025PGPPesticide General Permithigh
#D026NOINotice of Intenthigh
#D027NPDESNational Pollutant Discharge Elimination Systemhigh
#D028.govA .gov website belongs to an official government organization in the United States.high
#D029NPDES Permit Writers’ Clearinghousea searchable database containing resources such as permits, templates, and webinars that are shared by NPDES authorities.high
#D030WETWhole Effluent Toxicityhigh
#D031CWAClean Water Acthigh
#D032CAFOConcentrated Animal Feeding Operationshigh
#D033CORMIXa U.S. EPA-supported mixing zone model and decision support system for environmental impact assessment of regulatory mixing zones resulting from continuous point source discharges.high
#D034SWToolboxdesigned to assist NPDES permit writers and other practitioners estimate critical stream statistics such as the 7Q10.high
#D035Delft3Da modeling package that allows users to simulate flow, sediment transport, water quality in a range of water bodies.high
#D036EFDCEnvironment Fluid Dynamics Code (EFDC) can simulate both near- and far-field thermal mixing and can be applied to rivers, lakes, reservoirs, estuaries, and coasts.high
#D037CE-QUAL-W2can simulate thermal mixing in rivers, lakes, reservoirs, and estuaries, but is best suited for long and narrow water bodies because it assumes lateral homogeneity.high
#D038National Stormwater Calculatorestimates the annual amount of stormwater runoff from a specific location anywhere in the United States.high
#D039Storm Water Management Model (SWMM)used for planning, analysis and design related to stormwater runoff, combined and sanitary sewers, and other drainage systems in urban areas.high
#D040Hydrologic and Water Quality System (HAWQS)an interactive water quantity and quality modeling system to simulate the effect of management practices on water quality.high
#D041SWMM-CATThe Storm Water Management Model Adjustment Tool (SWMM-CAT) is an add-in tool to SWMM. It is a simple to use software utility that allows future projections to be incorporated into the Storm Water Management Model.high
#D042Delft3D-FLOWthe hydrodynamic module in the Delft 3D package that applies to thermal modeling.high