INSTALLER EXAM
1. What is the primary purpose of a residential septic
system?
A. To provide drinking water to the home
B. To generate electricity
C. To treat and disperse household wastewater
D. To collect stormwater runoff
Rationale: A septic system is designed to collect, treat, and
safely disperse wastewater generated from household plumbing
fixtures such as sinks, toilets, showers, and washing machines.
Proper treatment protects public health and groundwater
quality.
2. Which component of a septic system separates solids from
wastewater?
A. Distribution box
B. Drainfield
C. Effluent filter
D. Septic tank
Rationale: The septic tank is the primary treatment component
where solids settle to the bottom as sludge, oils float to the top
as scum, and partially treated liquid effluent exits toward the
drainfield.
3. What is the function of the drainfield?
A. To chlorinate wastewater
B. To distribute and further treat effluent in the soil
,C. To collect rainwater
D. To increase water pressure
Rationale: The drainfield disperses effluent into soil where
natural biological and physical processes remove harmful
organisms and contaminants before the water reaches
groundwater.
4. Which soil condition is generally most suitable for septic
drainfields?
A. Heavy clay with poor drainage
B. Bedrock at the surface
C. Well-drained loamy soil
D. Permanently saturated soil
Rationale: Well-drained loamy soils allow adequate filtration
and absorption while still retaining enough moisture for
microbial treatment of wastewater.
5. What is the purpose of a distribution box?
A. To store sludge
B. To filter grease
C. To evenly distribute effluent to drainfield lines
D. To disinfect wastewater
Rationale: A distribution box ensures that wastewater is
distributed evenly among drainfield trenches, preventing
overload of one section and extending system life.
6. What is sludge in a septic tank?
A. Floating grease layer
B. Settled solid waste at the bottom of the tank
,C. Clear wastewater leaving the tank
D. Rainwater entering the system
Rationale: Sludge consists of heavy solids that settle at the
bottom of the septic tank during the treatment process.
7. Which gas commonly forms in septic tanks and can be
dangerous?
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Hydrogen sulfide
Rationale: Hydrogen sulfide gas forms during decomposition of
waste and can be toxic, explosive, and deadly in confined spaces
such as septic tanks.
8. What is the minimum purpose of septic tank baffles?
A. To heat wastewater
B. To control flow and prevent solids from leaving the tank
C. To pump wastewater uphill
D. To soften water
Rationale: Baffles direct wastewater flow and reduce
disturbance of settled solids, preventing solids from entering
and clogging the drainfield.
9. Which condition can cause septic system failure?
A. Proper maintenance
B. Moderate water use
C. Excessive hydraulic loading
D. Regular inspections
, Rationale: Excessive water entering the system can overload the
tank and drainfield, reducing treatment effectiveness and
causing backups or surfacing effluent.
10. What is hydraulic loading?
A. Electrical pressure in pumps
B. Soil acidity measurement
C. The volume of wastewater entering the system
D. Chlorine concentration in water
Rationale: Hydraulic loading refers to the amount of
wastewater entering the septic system over time. Excessive
loading can overwhelm system components.
11. What is scum in a septic tank?
A. Settled mineral deposits
B. Floating fats, oils, and grease
C. Clean wastewater
D. Soil entering the tank
Rationale: Scum is composed mainly of oils, grease, and lighter
solids that float on the surface inside the septic tank.
12. Which pipe carries wastewater from the house to the
septic tank?
A. Lateral pipe
B. Header pipe
C. Vent stack
D. Building sewer
Rationale: The building sewer is the pipe that transports
wastewater from the home plumbing system to the septic tank.