Page 1 of 49
TEXAS ON-SITE SEWAGE FACILITIES (OSSF),
OSSF DR TEST PRACTICE 2026 EXAM WITH
ALL CURRENT TESTING QUESTIONS AND
CORRECT (VERIFIED) ANSWERS|TOP-RATED
A+.
OSSF
Ace your Texas OSSF (On-Site Sewage Facilities) Designated
Representative Test Practice exam by mastering system design,
soil evaluation, and state regulations for wastewater treatment.
This practice exam evaluates your knowledge of site
assessment, construction standards, and maintenance
requirements for septic systems. It is specifically designed to
prepare you for the official state certification and professional
practice in Texas.
6.67 cubic yards ✓ ✓...... ANSWER ....... How many cubic
yards of gravel would be needed to fill a ditch 3 feet deep, 10
feet wide, and 12 feet long with 18 inches of gravel? 1 cubic
yard = 27 cubic feet.
846 gals ✓ ✓...... ANSWER ....... A septic tank is 6 feet in
diameter and is 8 feet deep. How many gallons will it hold if
the overflow line is located half way up from the bottom?
, Page 2 of 49
1077gals ✓ ✓...... ANSWER ....... Calculate the working
liquid capacity (volume) for this septic tank. SEE PAGE 2-39!!
2,600 sqft ✓ ✓...... ANSWER ....... What is the surface
area (area in square feet) of an evapotranspiration system 40
feet wide and 65 feet long?
1.5 acres ✓ ✓...... ANSWER ....... Figure the acreage for a
piece of property that measures 256 feet on each of four
sides.
16,800sqft ,0.39 acres ✓ ✓...... ANSWER ....... Figure the
area of a lot that measures 60ft by 280ft
drip or spray irrigation ✓ ✓...... ANSWER ....... A disposal
option that might be considered in a clay soil would be a
________.
septic tank ✓ ✓...... ANSWER ....... The primary
treatment device providing the least or poorest treatment of
domestic wastewater would be _______.
, Page 3 of 49
vegetation uptake ✓ ✓...... ANSWER ....... Nitrogen or
nitrate removal in soil occurs by _________.
moisture, temperature, pH, and organic matter. ✓ ✓......
ANSWER ....... The factors influencing the survival of
bacteria in soil are _______.
the bacteria are larger than the pore openings in the soil ✓
✓...... ANSWER ....... Physical removal of bacteria by
straining occurs when _______.
suspended solid ✓ ✓...... ANSWER ....... A solid that can
be filtered out of the wastewater is a _________.
fresh, light in color, has dissolved oxygen ✓ ✓...... ANSWER
....... Which of the following describes domestic
wastewater as it leaves a home?
surface water pollution, groundwater contamination, and
standing sewage in neighborhoods ✓ ✓...... ANSWER .......
, Page 4 of 49
Which of the following are problems caused by
malfunctioning septic tank systems?
nitrate ✓ ✓...... ANSWER ....... An inorganic chemical that
affects human health is
hookworm, round worms, and tapeworms ✓ ✓......
ANSWER ....... Parasites (helminths) found in untreated
sewage include ________.
poliomyelitis and infectious hepatitis ✓ ✓...... ANSWER
....... Viruses are responsible for such diseases as
fecal coliform ✓ ✓...... ANSWER ....... A type of bacteria
that indicates sewage contamination is ________.
amoeba dysentery and Giardiasis ✓ ✓...... ANSWER .......
Protozoa are very simple animal organisms that may cause
________.
TEXAS ON-SITE SEWAGE FACILITIES (OSSF),
OSSF DR TEST PRACTICE 2026 EXAM WITH
ALL CURRENT TESTING QUESTIONS AND
CORRECT (VERIFIED) ANSWERS|TOP-RATED
A+.
OSSF
Ace your Texas OSSF (On-Site Sewage Facilities) Designated
Representative Test Practice exam by mastering system design,
soil evaluation, and state regulations for wastewater treatment.
This practice exam evaluates your knowledge of site
assessment, construction standards, and maintenance
requirements for septic systems. It is specifically designed to
prepare you for the official state certification and professional
practice in Texas.
6.67 cubic yards ✓ ✓...... ANSWER ....... How many cubic
yards of gravel would be needed to fill a ditch 3 feet deep, 10
feet wide, and 12 feet long with 18 inches of gravel? 1 cubic
yard = 27 cubic feet.
846 gals ✓ ✓...... ANSWER ....... A septic tank is 6 feet in
diameter and is 8 feet deep. How many gallons will it hold if
the overflow line is located half way up from the bottom?
, Page 2 of 49
1077gals ✓ ✓...... ANSWER ....... Calculate the working
liquid capacity (volume) for this septic tank. SEE PAGE 2-39!!
2,600 sqft ✓ ✓...... ANSWER ....... What is the surface
area (area in square feet) of an evapotranspiration system 40
feet wide and 65 feet long?
1.5 acres ✓ ✓...... ANSWER ....... Figure the acreage for a
piece of property that measures 256 feet on each of four
sides.
16,800sqft ,0.39 acres ✓ ✓...... ANSWER ....... Figure the
area of a lot that measures 60ft by 280ft
drip or spray irrigation ✓ ✓...... ANSWER ....... A disposal
option that might be considered in a clay soil would be a
________.
septic tank ✓ ✓...... ANSWER ....... The primary
treatment device providing the least or poorest treatment of
domestic wastewater would be _______.
, Page 3 of 49
vegetation uptake ✓ ✓...... ANSWER ....... Nitrogen or
nitrate removal in soil occurs by _________.
moisture, temperature, pH, and organic matter. ✓ ✓......
ANSWER ....... The factors influencing the survival of
bacteria in soil are _______.
the bacteria are larger than the pore openings in the soil ✓
✓...... ANSWER ....... Physical removal of bacteria by
straining occurs when _______.
suspended solid ✓ ✓...... ANSWER ....... A solid that can
be filtered out of the wastewater is a _________.
fresh, light in color, has dissolved oxygen ✓ ✓...... ANSWER
....... Which of the following describes domestic
wastewater as it leaves a home?
surface water pollution, groundwater contamination, and
standing sewage in neighborhoods ✓ ✓...... ANSWER .......
, Page 4 of 49
Which of the following are problems caused by
malfunctioning septic tank systems?
nitrate ✓ ✓...... ANSWER ....... An inorganic chemical that
affects human health is
hookworm, round worms, and tapeworms ✓ ✓......
ANSWER ....... Parasites (helminths) found in untreated
sewage include ________.
poliomyelitis and infectious hepatitis ✓ ✓...... ANSWER
....... Viruses are responsible for such diseases as
fecal coliform ✓ ✓...... ANSWER ....... A type of bacteria
that indicates sewage contamination is ________.
amoeba dysentery and Giardiasis ✓ ✓...... ANSWER .......
Protozoa are very simple animal organisms that may cause
________.
