Washington State (WOSSA) Septic
Installer Practice Exam 2026 | Updated
Actual Exam with Verified Questions and
Correct Solutions | Expert Verified |
Guaranteed Pass | Latest Update
/. ANSI - Answer-✅American National Standards Institute
/.BOD - Answer-✅biochemical oxygen demand, typically expressed in mg/L.
/.CBOD - Answer-✅Carbonaceous Biochemical Oxygen Demand, expressed in mg/L.
/.FC - Answer-✅Fecal Coliform, expressed in number of colonies 100/ml.
/.LOSS - Answer-✅large on-site sewage system
/.NSF - Answer-✅Nation Sanitation Foundation International
/.O&G - Answer-✅Oils and Grease, component of sewage typically originating from
food stuffs (animal fats of vegetable oils) expressed in mg/L.
/.RS&G - Answer-✅Recommended Standards and Guidance
/.SSAS - Answer-✅a subsurface soil absorption system
/.TAC - Answer-✅Technical Advisory Committee established in WAC 247-272A-0400
/.TN - Answer-✅Total Nitrogen, expressed in mg/L.
/.TSS - Answer-✅Total Suspended Solids. A measure of the total suspended solids in a
given solution, expressed in mg/L.
/.USEPA - Answer-✅United States Environmental Protection Agency
,/.Additive - Answer-✅a commercial product added to an on-site sewage system
intended to affect the performance or aesthetics of an on-site sewage system
/.Approved - Answer-✅Acceptable to the authority having jurisdiction. Local health
officer or the department
/.BED - Answer-✅a soil dispersal component consisting of an excavation with a width
greater than 3 feet
/.Building Sewer - Answer-✅that part of the horizontal piping of a drainage system
which starts from the end of the building drain and which receives the discharge of the
building drain and conveys it to a public sewer, private sewer, individual sewage
disposal system or other point of disposal. It begins two feet outside the building wall
and conveys sewage from the building drain to the remaining portions of the on-site
sewage system.
/.Cesspool - Answer-✅a covered hole or pit for receiving drainage or sewage, as from a
house allowing liquid to seep into the surronding rock or soil
/.Conforming System - Answer-✅an on-site sewage system of component meeting
rules of: New construction requirements
Approved and installed within previous requirements
Permitted by WAC-246-272A-0420
/.Cover Material - Answer-✅Soil placed over dispersal component, made up of mineral
material with no greater than 10% organic content. Cover may contain organic surface
material, an organic landscaper to help reduce and contain soil erosion.
/.Cuts and Banks - Answer-✅a naturally occurring or artificially formed slope greater
than one hundred percent (forty-five degrees) and extending vertically at least five from
the toe of the slope to top of the slope.
/.Department - Answer-✅Washington State Department of Health
/.Designer - Answer-✅Person who matches site and soil characteristics with approved
components
/.Design Flow - Answer-✅Means the maximum volume of sewage a residence,
structure or other facility is estimated to generate in a twenty-four hour period. It
incorporates both an operating capacity and a surge capacity for the system during
periodic heavy use events. The sizing and design of a on-site sewage system
component is based on the design flow.
/.Development - Answer-✅The creation of a residence, structure, facility, subdivision,
area, or similar activity resulting in the production of sewage.
,/.Disinfection - Answer-✅The process of destroying pathogens in sewage through the
application of chlorination, ultra-violent light, or ozonation.
/.Distribution Technology - Answer-✅any arrangement of equipment and/or material
that distributes sewage within and on-site sewage system.
/.Drainfield - Answer-✅subsurface soil absorption system, and soil dispersal component
/.Drainrock - Answer-✅cleaned washed gravel or crushed rock ranging in size from 3/4"
to 2.5", and containing no more than two percent by weight passing a US No.8 sieve
and no more than one percent by weight passing through a US No. 200 Sieve.
/.Effluent - Answer-✅liquid waste discharged to a septic tank or other on-site sewage
system
/.Expanding Clay - Answer-✅means a clay soil with the mineralogy of clay particles.
Clay particles expand when absorbing water
/.expansion - Answer-✅a change in residence, facility or site that results in the quantity
of sewage to exceed the original design
/.Extremely gravely - Answer-✅soils with 60% or more, but not less than 90% rock
fragments by volume.
/.Failure - Answer-✅a condition of an on-site sewage component that threatens the
public health by inadequately treating the sewage, or creating a potential direct or
indirect contact between sewage and the public.
/.Fecal coliform bacteria - Answer-✅bacteria found in the intestinal tracts of warm-
blooded animals that are cultured in standard tests. Generally expressed as colonies
per 100 ml.
/.Gravely - Answer-✅Soils with 15% or more, but less than 35% rock fragments by
volume.
/.Gray Water - Answer-✅Sewage from bathtubs, showers, bathroom sinks, kitchen
sinks, washing machines, and dishwashers.
/.Ground water - Answer-✅Subsurface water in the zone of saturated soils, seasonally,
permanently, or as the result of the tides.
/.Holding tank sewage system - Answer-✅an on-site sewage system that a holding tank
with no discharge outlet
, /.hydraulic loading rate - Answer-✅the amount of effluent applied to a given treatment
step, expressed as gallons per square foot per day, (gal./sq.ft./day)
/.industrial waste - Answer-✅Waste from production of consumer goods, mining,
agriculture and petroleum extraction and refining
/.Infiltrative surface - Answer-✅Surface within a treatment component or soil dispersal
component to which effluent is applied and through which effluent moves into original,
undisturbed soil or other porous treatment media.
/.Installer - Answer-✅a person approved by the local health office to install on-site
sewage systems or components
/.Local Health Officer - Answer-✅The provincial or municipal health officer.
/.Maintenance - Answer-✅The actions necessary to keep the on-site sewage system
components functioning as designed
/.Massive structure - Answer-✅the condition of a soil layer in which the layer appears
as a coherent of solid mass not separated into peds of any kind
/.Moderated structure - Answer-✅Well- formed distinct peds evident in undisturbed soil.
When disturbed, soil material parts into mixture of whole peds, broken peds, and
material that is not in peds.
/.Monitoring - Answer-✅Periodic or continuous surveillance of on-site sewage system,
which is performed by observations and measurements, to determine if the system is
functioning as intended and if system is in need of maintenance.
/.On-site sewage system (OSS) - Answer-✅An integrated system of components ,
located on or nearby the property it serves. that conveys, stores, treats, and/or provides
subsurface soil treatment and dispersal of sewage. It consists of a collection system, a
treatment component or treatment sequence, and a soil dispersal component.
/.Operating capacity - Answer-✅the average daily volume of sewage an OSS can treat
and disperse on a sustained basis. The operating capacity, which is lower than design
flow, is an integral part of the design and is used as an index in OSS monitoring.
/.Ordinary High Water Mark - Answer-✅The point on the bank or shore where water is
present often enough so that the upland begins to look different from the lake or stream
bed.
Installer Practice Exam 2026 | Updated
Actual Exam with Verified Questions and
Correct Solutions | Expert Verified |
Guaranteed Pass | Latest Update
/. ANSI - Answer-✅American National Standards Institute
/.BOD - Answer-✅biochemical oxygen demand, typically expressed in mg/L.
/.CBOD - Answer-✅Carbonaceous Biochemical Oxygen Demand, expressed in mg/L.
/.FC - Answer-✅Fecal Coliform, expressed in number of colonies 100/ml.
/.LOSS - Answer-✅large on-site sewage system
/.NSF - Answer-✅Nation Sanitation Foundation International
/.O&G - Answer-✅Oils and Grease, component of sewage typically originating from
food stuffs (animal fats of vegetable oils) expressed in mg/L.
/.RS&G - Answer-✅Recommended Standards and Guidance
/.SSAS - Answer-✅a subsurface soil absorption system
/.TAC - Answer-✅Technical Advisory Committee established in WAC 247-272A-0400
/.TN - Answer-✅Total Nitrogen, expressed in mg/L.
/.TSS - Answer-✅Total Suspended Solids. A measure of the total suspended solids in a
given solution, expressed in mg/L.
/.USEPA - Answer-✅United States Environmental Protection Agency
,/.Additive - Answer-✅a commercial product added to an on-site sewage system
intended to affect the performance or aesthetics of an on-site sewage system
/.Approved - Answer-✅Acceptable to the authority having jurisdiction. Local health
officer or the department
/.BED - Answer-✅a soil dispersal component consisting of an excavation with a width
greater than 3 feet
/.Building Sewer - Answer-✅that part of the horizontal piping of a drainage system
which starts from the end of the building drain and which receives the discharge of the
building drain and conveys it to a public sewer, private sewer, individual sewage
disposal system or other point of disposal. It begins two feet outside the building wall
and conveys sewage from the building drain to the remaining portions of the on-site
sewage system.
/.Cesspool - Answer-✅a covered hole or pit for receiving drainage or sewage, as from a
house allowing liquid to seep into the surronding rock or soil
/.Conforming System - Answer-✅an on-site sewage system of component meeting
rules of: New construction requirements
Approved and installed within previous requirements
Permitted by WAC-246-272A-0420
/.Cover Material - Answer-✅Soil placed over dispersal component, made up of mineral
material with no greater than 10% organic content. Cover may contain organic surface
material, an organic landscaper to help reduce and contain soil erosion.
/.Cuts and Banks - Answer-✅a naturally occurring or artificially formed slope greater
than one hundred percent (forty-five degrees) and extending vertically at least five from
the toe of the slope to top of the slope.
/.Department - Answer-✅Washington State Department of Health
/.Designer - Answer-✅Person who matches site and soil characteristics with approved
components
/.Design Flow - Answer-✅Means the maximum volume of sewage a residence,
structure or other facility is estimated to generate in a twenty-four hour period. It
incorporates both an operating capacity and a surge capacity for the system during
periodic heavy use events. The sizing and design of a on-site sewage system
component is based on the design flow.
/.Development - Answer-✅The creation of a residence, structure, facility, subdivision,
area, or similar activity resulting in the production of sewage.
,/.Disinfection - Answer-✅The process of destroying pathogens in sewage through the
application of chlorination, ultra-violent light, or ozonation.
/.Distribution Technology - Answer-✅any arrangement of equipment and/or material
that distributes sewage within and on-site sewage system.
/.Drainfield - Answer-✅subsurface soil absorption system, and soil dispersal component
/.Drainrock - Answer-✅cleaned washed gravel or crushed rock ranging in size from 3/4"
to 2.5", and containing no more than two percent by weight passing a US No.8 sieve
and no more than one percent by weight passing through a US No. 200 Sieve.
/.Effluent - Answer-✅liquid waste discharged to a septic tank or other on-site sewage
system
/.Expanding Clay - Answer-✅means a clay soil with the mineralogy of clay particles.
Clay particles expand when absorbing water
/.expansion - Answer-✅a change in residence, facility or site that results in the quantity
of sewage to exceed the original design
/.Extremely gravely - Answer-✅soils with 60% or more, but not less than 90% rock
fragments by volume.
/.Failure - Answer-✅a condition of an on-site sewage component that threatens the
public health by inadequately treating the sewage, or creating a potential direct or
indirect contact between sewage and the public.
/.Fecal coliform bacteria - Answer-✅bacteria found in the intestinal tracts of warm-
blooded animals that are cultured in standard tests. Generally expressed as colonies
per 100 ml.
/.Gravely - Answer-✅Soils with 15% or more, but less than 35% rock fragments by
volume.
/.Gray Water - Answer-✅Sewage from bathtubs, showers, bathroom sinks, kitchen
sinks, washing machines, and dishwashers.
/.Ground water - Answer-✅Subsurface water in the zone of saturated soils, seasonally,
permanently, or as the result of the tides.
/.Holding tank sewage system - Answer-✅an on-site sewage system that a holding tank
with no discharge outlet
, /.hydraulic loading rate - Answer-✅the amount of effluent applied to a given treatment
step, expressed as gallons per square foot per day, (gal./sq.ft./day)
/.industrial waste - Answer-✅Waste from production of consumer goods, mining,
agriculture and petroleum extraction and refining
/.Infiltrative surface - Answer-✅Surface within a treatment component or soil dispersal
component to which effluent is applied and through which effluent moves into original,
undisturbed soil or other porous treatment media.
/.Installer - Answer-✅a person approved by the local health office to install on-site
sewage systems or components
/.Local Health Officer - Answer-✅The provincial or municipal health officer.
/.Maintenance - Answer-✅The actions necessary to keep the on-site sewage system
components functioning as designed
/.Massive structure - Answer-✅the condition of a soil layer in which the layer appears
as a coherent of solid mass not separated into peds of any kind
/.Moderated structure - Answer-✅Well- formed distinct peds evident in undisturbed soil.
When disturbed, soil material parts into mixture of whole peds, broken peds, and
material that is not in peds.
/.Monitoring - Answer-✅Periodic or continuous surveillance of on-site sewage system,
which is performed by observations and measurements, to determine if the system is
functioning as intended and if system is in need of maintenance.
/.On-site sewage system (OSS) - Answer-✅An integrated system of components ,
located on or nearby the property it serves. that conveys, stores, treats, and/or provides
subsurface soil treatment and dispersal of sewage. It consists of a collection system, a
treatment component or treatment sequence, and a soil dispersal component.
/.Operating capacity - Answer-✅the average daily volume of sewage an OSS can treat
and disperse on a sustained basis. The operating capacity, which is lower than design
flow, is an integral part of the design and is used as an index in OSS monitoring.
/.Ordinary High Water Mark - Answer-✅The point on the bank or shore where water is
present often enough so that the upland begins to look different from the lake or stream
bed.
