ASSE 12080 (14)-Practice Questions and
Answers.
The domestic (potable) water system in a hospital has had Legionella positivity averaging 45%
over six sampling dates in the past 12 months. The hospital does not have a supplemental
disinfection system but has hyperchlorinated the domestic water at 20 parts per million free
chlorines for a 2-hour period three times in the past 9 months. The public water supply at the
point of building entry (POE) has had a disinfectant residual ranging from 0 to 0.2 parts per
million over the last four months, has tested Legionella-positive (Legionella pneumophila
serogroup 1) in 2 of the last 3 sampling rounds, and has a temperature range of 68 to 78
degrees F (20 to 26 degrees C) for six months of the year. What steps should the hospital's WMP
team consider? - Answer Notify the water provider of the POE Legionella and disinfectant test
results. Install a continuous supplemental disinfection system that is effective against Legionella
and appropriate for this domestic water system
When applying supplemental disinfection in a domestic (potable) water system, disinfection
byproducts are a concern with all but which of the following: - Answer Ultraviolet light
Which of the following, if applied in a domestic (potable) water system near the point of
building entry (POE), is least likely to provide a disinfectant residual throughout the system? -
Answer Ultraviolet light
A hotel with high domestic water Legionella positivity and concentrations installs a
supplemental disinfection system. Assuming the supplemental disinfection system was properly
selected, designed, and installed, it should be able to control Legionella with little or no
maintenance or inspection. Moreover, it should allow the facility to eliminate many of the
domestic water control measures in its WMP - Answer False
Per the US EPA National Primary Drinking Water Regulations, the MCL for Total Trihalomethanes
(TTHMs) is ______ mg/L and the MCL for Total Haloacetic Acids (HAA5) is _______ ppm: -
Answer 0.080; 0.060
A 25-story office building that has been fully occupied for many months is tested for Legionella
for the first time. 24 samples are collected, one hot and one cold pre-flush water sample from a
restroom on the even numbered floors. Each restroom has a 15-gallon water heater supplying
its faucets. On the day samples were collected for Legionella testing, the free chlorine residual
was 0.9 parts per million (ppm) at the point of entry (POE) to the building, 0.5 to 0.8 ppm in the
cold water at the outlets sampled, and 0.2 to 0.4 ppm in the hot water at the outlets sampled.
Legionella was found in one sample, a hot water sample from a restroom on the 14th floor, at 8
colony forming units per milliliter (CFU/mL). What would be the most reasonable response to
these test results? - Answer Test to confirm a free chlorine residual in the hot and cold water
at the Legionella-positive outlet and then run the hot and cold water at that outlet for 5
minutes, wearing appropriate PPE. Collect a pre-flush and post-flush sample from the water
heater, send it to the lab for Legionella testing, and then drain and flush the heater before
returning it to service. Also confirm that the hot water temperature is within the target range.
, An ice machine on a patient floor in a hospital has tested Legionella-positive each month for the
past 6 months even though it has been cleaned and disinfected after each Legionella finding.
The best next step could include all but which of the following? - Answer Clean and disinfect
the machine weekly.
A hotel has 16 decorative fountains. Of these three, what would be the best way to interpret
Legionella test results for samples collected from the decorative fountains? - Answer Presence
of Legionella or Legionella concentrations per sample in a given fountain
Legionella pneumophila serogroup 1 was found in a cold-water sample from a domestic
(potable) water faucet in a hospital intensive care unit patient room. After running cold water at
the faucet for two minutes, no disinfectant residual was found. Which remediation method
would be an appropriate consideration for this faucet? - Answer Install a sub-micron (< 0.2
micron) filter on the faucet while investigating other solutions.
What should be considered in deciding on a domestic (potable) water supplemental disinfection
technology aimed to control Legionella and intended for continuous, long-term use? - Answer
All of the above
States that regulate supplemental disinfection of domestic (potable) water systems typically
require reporting of test results for all but which of the following per the Safe Drinking Water
Act? - Answer Legionella
Per the CDC (US), sample volume collected for Legionella testing should be ________ for
outbreak investigations and a minimum of ________ for routine environmental sampling of
potable water. - Answer 1 liter; 250 mL
The domestic (potable) water system in a college dormitory is tested for Legionella prior to
reopening for the fall semester after having been closed and unoccupied for 11 weeks.
Legionella was found in 8 of 12 samples collected, at concentrations ranging from 1 to 70 colony
forming units per milliliter. Student move-in day is 10 days away. The public water supply is
treated with chlorine. At the point of entry (POE) to the building, a free chlorine residual was
not detected until running water for more than 10 minutes but eventually reached 0.7 parts per
million free chlorine. What is likely the best option among these four? - Answer Hire a water
treatment company with expertise in domestic water remediation to hyperchlorinate and flush
the hot and cold domestic water system, and retest for Legionella 3 to 7 days and again 30 to 60
days after the procedure.
Per the CDC (US), a full investigation should be conducted if only 1 or more cases of
Legionnaires' Disease have been identified at a correctional facility or other facility where
people cannot leave the premises. - Answer True
Answers.
The domestic (potable) water system in a hospital has had Legionella positivity averaging 45%
over six sampling dates in the past 12 months. The hospital does not have a supplemental
disinfection system but has hyperchlorinated the domestic water at 20 parts per million free
chlorines for a 2-hour period three times in the past 9 months. The public water supply at the
point of building entry (POE) has had a disinfectant residual ranging from 0 to 0.2 parts per
million over the last four months, has tested Legionella-positive (Legionella pneumophila
serogroup 1) in 2 of the last 3 sampling rounds, and has a temperature range of 68 to 78
degrees F (20 to 26 degrees C) for six months of the year. What steps should the hospital's WMP
team consider? - Answer Notify the water provider of the POE Legionella and disinfectant test
results. Install a continuous supplemental disinfection system that is effective against Legionella
and appropriate for this domestic water system
When applying supplemental disinfection in a domestic (potable) water system, disinfection
byproducts are a concern with all but which of the following: - Answer Ultraviolet light
Which of the following, if applied in a domestic (potable) water system near the point of
building entry (POE), is least likely to provide a disinfectant residual throughout the system? -
Answer Ultraviolet light
A hotel with high domestic water Legionella positivity and concentrations installs a
supplemental disinfection system. Assuming the supplemental disinfection system was properly
selected, designed, and installed, it should be able to control Legionella with little or no
maintenance or inspection. Moreover, it should allow the facility to eliminate many of the
domestic water control measures in its WMP - Answer False
Per the US EPA National Primary Drinking Water Regulations, the MCL for Total Trihalomethanes
(TTHMs) is ______ mg/L and the MCL for Total Haloacetic Acids (HAA5) is _______ ppm: -
Answer 0.080; 0.060
A 25-story office building that has been fully occupied for many months is tested for Legionella
for the first time. 24 samples are collected, one hot and one cold pre-flush water sample from a
restroom on the even numbered floors. Each restroom has a 15-gallon water heater supplying
its faucets. On the day samples were collected for Legionella testing, the free chlorine residual
was 0.9 parts per million (ppm) at the point of entry (POE) to the building, 0.5 to 0.8 ppm in the
cold water at the outlets sampled, and 0.2 to 0.4 ppm in the hot water at the outlets sampled.
Legionella was found in one sample, a hot water sample from a restroom on the 14th floor, at 8
colony forming units per milliliter (CFU/mL). What would be the most reasonable response to
these test results? - Answer Test to confirm a free chlorine residual in the hot and cold water
at the Legionella-positive outlet and then run the hot and cold water at that outlet for 5
minutes, wearing appropriate PPE. Collect a pre-flush and post-flush sample from the water
heater, send it to the lab for Legionella testing, and then drain and flush the heater before
returning it to service. Also confirm that the hot water temperature is within the target range.
, An ice machine on a patient floor in a hospital has tested Legionella-positive each month for the
past 6 months even though it has been cleaned and disinfected after each Legionella finding.
The best next step could include all but which of the following? - Answer Clean and disinfect
the machine weekly.
A hotel has 16 decorative fountains. Of these three, what would be the best way to interpret
Legionella test results for samples collected from the decorative fountains? - Answer Presence
of Legionella or Legionella concentrations per sample in a given fountain
Legionella pneumophila serogroup 1 was found in a cold-water sample from a domestic
(potable) water faucet in a hospital intensive care unit patient room. After running cold water at
the faucet for two minutes, no disinfectant residual was found. Which remediation method
would be an appropriate consideration for this faucet? - Answer Install a sub-micron (< 0.2
micron) filter on the faucet while investigating other solutions.
What should be considered in deciding on a domestic (potable) water supplemental disinfection
technology aimed to control Legionella and intended for continuous, long-term use? - Answer
All of the above
States that regulate supplemental disinfection of domestic (potable) water systems typically
require reporting of test results for all but which of the following per the Safe Drinking Water
Act? - Answer Legionella
Per the CDC (US), sample volume collected for Legionella testing should be ________ for
outbreak investigations and a minimum of ________ for routine environmental sampling of
potable water. - Answer 1 liter; 250 mL
The domestic (potable) water system in a college dormitory is tested for Legionella prior to
reopening for the fall semester after having been closed and unoccupied for 11 weeks.
Legionella was found in 8 of 12 samples collected, at concentrations ranging from 1 to 70 colony
forming units per milliliter. Student move-in day is 10 days away. The public water supply is
treated with chlorine. At the point of entry (POE) to the building, a free chlorine residual was
not detected until running water for more than 10 minutes but eventually reached 0.7 parts per
million free chlorine. What is likely the best option among these four? - Answer Hire a water
treatment company with expertise in domestic water remediation to hyperchlorinate and flush
the hot and cold domestic water system, and retest for Legionella 3 to 7 days and again 30 to 60
days after the procedure.
Per the CDC (US), a full investigation should be conducted if only 1 or more cases of
Legionnaires' Disease have been identified at a correctional facility or other facility where
people cannot leave the premises. - Answer True
