Definitions

The terms “Department,” “Director,” and “Waters” are defined in Section 39-103, Idaho Code. The term “Ground water” (Groundwater) is defined in Section 39-121, Idaho Code. (7-1-25) 01. Abandoned System. A system that no longer receives blackwaste or wastewater due to diversion to another treatment system or due to termination of waste flow for more than two (2) years. (7-1-25) IDAHO ADMINISTRATIVE CODE IDAPA 58.01.03 – Individual/Subsurface Sewage Department of Environmental Quality Disposal & Cleaning of Septic Tanks Rules Section 003 Page 4 02. Absorption Bed. A drainfield excavation exceeding six (6) feet in width. (7-1-25) 03. Alternative System. Any system other than a standard system for which the Department has issued design guidelines or the Director determines is a modification of a standard system. (7-1-25) a. A basic alternative system is any capping fill system, extra drainrock trench, gravelless trench system, steep-slope system, or other system specified in the TGM. (7-1-25) b. A complex alternative system is any evapotranspiration system, ETPS, lagoon system, LSAS, pressure distribution system, PWTP system, intermittent sand filter, sand mound, or other system specified in the TGM. (7-1-25) 04. Bedroom. A habitable room within a dwelling that meets state or local building code requirements applicable to bedrooms and includes methods of ingress and egress. The local building authority may designate any additional room as a bedroom. (7-1-25) 05. Blackwaste. As defined in IDAPA 58.01.16, Wastewater Rules. (7-1-25) 06. Blackwater. As defined in IDAPA 58.01.16, Wastewater Rules. (7-1-25) 07. Building Sewer. The extension of the building drain beginning five (5) feet outside the inner face of the building wall. (3-31-22) 08. Central System. Any system that receives blackwaste or wastewater in volumes exceeding twenty- five hundred (2,500) gallons per day; any system that receives blackwaste or wastewater from more than two (2) dwelling units or more than two (2) buildings under separate ownership. (7-1-25) 09. Construct. To make, form, excavate, alter, expand, repair, or install a system. (7-1-25) 10. Drainfield. A system of aggregate-filled trenches, gravelless chamber systems, drip systems, absorption beds, or other approved subsurface dispersal methods that distribute wastewater effluent into the soil. Also known as a “leachfield” or “soil absorption system.” (7-1-25) 11. Dwelling Unit. A single unit with complete independent living facilities for one (1) or more persons, including permanent improvements for living, sleeping, eating, cooking, and sanitation. (7-1-25) 12. Existing System. Any system installed before the effective date of these rules. (7-1-25) 13. Expand. To enlarge any nonfailing system. (3-31-22) 14. Extended Treatment Package System (ETPS). A wastewater treatment product that requires electricity and provides secondary or tertiary wastewater treatment to septic tank effluent for systems receiving less than twenty-five hundred (2,500) gallons per day. (7-1-25) 15. Failing System. Any system that exhibits one (1) or more of the following characteristics: (7-1-25) a. Does not meet the intent stated in Subsection 004.01. (7-1-25) b. Fails to accept blackwaste and wastewater; or (7-1-25) c. Discharges blackwaste or wastewater into the waters or onto the ground surface. (7-1-25) 16. Gray Water. As defined in IDAPA 58.01.16, Wastewater Rules. (7-1-25) 17. High Groundwater Level -- Normal, Seasonal. High groundwater level may be established by the soil characteristics, actual groundwater monitoring, or historic records. (7-1-25) IDAHO ADMINISTRATIVE CODE IDAPA 58.01.03 – Individual/Subsurface Sewage Department of Environmental Quality Disposal & Cleaning of Septic Tanks Rules Section 003 Page 5 a. Normal high groundwater level is the highest elevation of groundwater that is maintained or exceeded continuously for six (6) weeks a year. (7-1-25) b. The seasonal high groundwater level is the highest elevation of groundwater that is maintained or exceeded continuously for one (1) week a year. (7-1-25) 18. Individual System. Any standard, alternative, or subsurface disposal system that is not a central system. (7-1-25) 19. Install. To excavate or put in place a system or component of a system. (7-1-25) 20. Installer. Any person, corporation, or firm engaged in the business of excavation or construction of individual or subsurface sewage disposal systems in the State. (7-1-25) 21. Large Soil Absorption System (LSAS). A subsurface sewage disposal system designed to receive two thousand five hundred (2,500) gallons of wastewater or more per day, including where the total wastewater flow from the entire proposed project exceeds two thousand five hundred (2,500) gallons per day, but is separated into absorption modules that receive less than two thousand five hundred (2,500) gallons per day. (7-1-25) 22. Limiting Layer. A subsurface layer or material that severely limits the capability of the soil to treat or absorb wastewater including, but not limited to, water tables, fractured bedrock, excessively permeable material, and impermeable material. (7-1-25) 23. Manufactured Medium Sand. Sand that meets the following gradation requirements: (3-31-22) 24. Minimum Tank Capacity. The minimum required total liquid capacity of the septic tank facility. (7-1-25) 25. New System. A system that is or might be approved on or after the effective date of these rules. (7-1-25) 26. Nondischarging System. Any system designed and constructed to prevent subsurface discharge of blackwaste or wastewater. (7-1-25) 27. Pollutants. As defined in IDAPA 58.01.16, Wastewater Rules. (7-1-25) 28. Proprietary Wastewater Treatment Product (PWTP). A manufactured product that provides passive treatment to septic tank effluent for systems receiving less than twenty-five hundred (2,500) gallons per day. (7-1-25) Manufactured medium sand allowable particle size percent composition. Sieve Size Passing (%) 4 95–100 8 80–100 16 50–85 30 25–60 50 10–30 100 2–10 200 <2 IDAHO ADMINISTRATIVE CODE IDAPA 58.01.03 – Individual/Subsurface Sewage Department of Environmental Quality Disposal & Cleaning of Septic Tanks Rules Section 004 Page 6 29. Repair. To remake, reform, replace, or enlarge a failing system, or any component as is necessary to restore proper operation. (7-1-25) 30. Scarp. The side of a hill, canyon, ditch, river bank, roadcut, or other geological feature characterized by a slope of forty-five (45) degrees (100% slope) or more from the horizontal. (7-1-25) 31. Septic Tank. A watertight, covered receptacle designed and constructed to receive wastewater discharge, separate solids from liquid, digest organic matter, store digested solids through a period of detention, and allow clarified liquids to discharge for final disposal. (7-1-25) 32. Septic Tank Facility. A septic tank or series of septic tanks preceding a subsurface disposal system. Tanks or compartments used for housing pretreatment products or used as dosing chambers are not considered part of the septic tank facility. (7-1-25) 33. Septage. As defined in IDAPA 58.01.16, Wastewater Rules. (7-1-25) 34. Service Provider. Any person, corporation, or firm engaged in the business of providing operation, maintenance, and monitoring of complex alternative systems in the state of Idaho. (3-31-22) 35. Sewage. As defined in IDAPA 58.01.16, Wastewater Rules. (7-1-25) 36. Standard System. An effluent sewer, one (1) or more aggregate filled trenches, and a gravity flow wastewater distribution system. (7-1-25) 37. Subsurface Disposal System. Any system with a point of discharge beneath the earth’s surface. (7-1-25) 38. Surface Water - Intermittent, Permanent, Temporary. (3-31-22) a. Any waters including but not limited to, lakes, streams, canals, and ditches. (7-1-25) b. Intermittent surface water exists continuously for more than two (2) months but not more than six (6) months a year. (7-1-25) c. Permanent surface water exists continuously for more than six (6) months a year. (7-1-25) d. Temporary surface water exists continuously for less than two (2) months a year. (7-1-25) 39. System. Beginning at the point of entry, physically connected piping, treatment devices, receptacles, structures, or areas of land designed, used or dedicated to convey, store, stabilize, neutralize, treat, or dispose of blackwaste or wastewater. (7-1-25) 40. Trench. A drainfield excavation six (6) feet or less in width. (7-1-25) 41. Wastewater. As defined in IDAPA 58.01.16, Wastewater Rules. (7-1-25)