Legionella Environmental Assessment Form

Form Approved
OMB No. 0920-1011
Exp. Date 03/31/2017

Legionella Environmental Assessment Form

Public reporting burden of this collection of information is estimated to average 120 minutes per response, including the time for
reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing
the collection of information. An agency may not conduct or sponsor, and a person is not required to respond to a collection of
information unless it displays a currently valid OMB control number. Send comments regarding this burden estimate or any other
aspect of this collection of information including suggestions for reducing this burden to CDC/ATSDR Reports Clearance Officer;
1600 Clifton Road NE, MS D-74 Atlanta, Georgia 30333; ATTN: PRA (0920-1011)

Centers for Disease Control and Prevention

Legionella Environmental Assessment Form
HOW TO USE THIS FORM
This form enables public health officials to gain a thorough understanding of a facility’s water systems and assist facility
management with minimizing the risk of legionellosis. It can be used along with epidemiologic information to determine whether
to conduct Legionella environmental sampling and to develop a sampling plan. The assessment should be performed on-site by an
epidemiologist and an environmental health specialist with knowledge of the ecology of Legionella. Keep in mind that conditions
promoting Legionella amplification include water stagnation, warm temperatures (77-108°F or 25-42°C), availability of organic
matter, and lack of residual disinfectant such as chlorine. For training and information, please visit CDC’s legionellosis resources
webpage at: http://www.cdc.gov/legionella/outbreak-toolkit/.
Complete the form in as much detail as possible. Do not leave sections blank; if a question does not apply, write “N/A”. If a
question applies but cannot be answered, explain why. Where applicable, specify the units of measurement being used (e.g., ppm).
Completion of the form may take several hours.

BEFORE ARRIVING ON SITE
❒❒ Request the attendance of the lead facility manager as well as others who have a detailed knowledge of the
facility’s water systems, such as a facility engineer or industrial hygienist.
❒❒ Request that they have maintenance logs and blueprints available for the meeting.
❒❒ Bring a plastic bottle, thermometer, pH test kit, and a chlorine test kit that can detect a wide range of residual
disinfectant (<1 ppm for potable water and up to 10 ppm for whirlpool spas).
❒❒ If the epidemiologic information available suggests a particular source (e.g., whirlpool spa, cooling tower),
request that they shut it down (but do not drain or disinfect) in order to stop transmission.

INSTRUCTIONS FOR MEASURING WATER PARAMETERS IN THE PREMISE PLUMBING
(TABLE P. 8)

It is very important to measure and document the current physical and chemical characteristics of the potable water, as this
can help determine whether conditions are likely to support Legionella amplification.
STEP 1: Plan a sampling strategy that incorporates all central hot water heaters/boilers and various points along each loop
of the potable water system. For example, if the facility has one loop serving all occupant rooms, an occupant room near
(proximal) the central hot water heater and another at the farthest point (distal) of the loop should be sampled.
STEP 2: For each sampling point (e.g., tap in an occupant room):
a. Turn on the hot water tap. Collect the first 50 ml from the tap. Measure the free chlorine residual and pH. Document
the findings in the table on p. 8. Note: If there is no residual chlorine in the hot water, measure it in the cold water.
Note: Total chlorine should be measured instead of free chlorine if the method of disinfection is not chlorine (e.g.,
monochloramine).
b. Allow the hot water tap to run until it is as hot as it will get. Collect 50 ml and measure the temperature. Document the
temperature and the time it took to reach the maximum temperature.

National Center for Immunization and Respiratory Diseases
Division of Bacterial Diseases
06/2015

CS254961-A

LEGIONELLA ENVIRONMENTAL ASSESSMENT FORM
Persons completing the assessment:
Name: _______________________________ Job Title: __________________ Organization:_________________
Telephone: ___________________________ E-mail: ___________________
Name: _______________________________ Job Title:___________________ Organization:_________________
Telephone: _
E-mail:
Assessment details:
Facility Name: _____________________________________________ Date of Assessment: __________________
Facility Address: ______________________________________________________________________________

street

city

state zip

Person(s) interviewed during assessment:
Name: _______________________________ Job Title: __________________
Name: _______________________________ Job Title: __________________
Name: _______________________________ Job Title: __________________
Facility Characteristics
1. Is this a healthcare facility or senior living facility with skilled nursing care (e.g., hospital, long term care/rehab/assisted living/
skilled nursing facility, or clinic)?
❑ YES ➔ If yes, skip to Q.3 & also complete Appendix A.
❑ NO
2. If NO, indicate type of facility (check all that apply):
❒ Senior living facility (e.g., retirement home without skilled nursing care)
❒ Other residential building (e.g., apartment, condominium)
❒ Hotel, motel, or resort
❒ Recreational facility (e.g., health club, water park)
❒ Office building
❒ Manufacturing facility
❒ Restaurant
❒ Other ___________________________________________________
3. Total number of buildings on campus: __________ Total number of buildings being assessed: __________
4. Total number of rooms that can be occupied overnight (e.g., patient rooms, hotel rooms): _________
5. Does occupancy vary throughout the year?

❑ YES

❑ NO

If YES, seasons with lowest occupancy (check all that apply):
❑ Winter ❑ Spring ❑ Summer ❑ Fall
6. Are any occupant rooms taken out of service during specific parts of the year, e.g., low season?
❑ YES ❑ NO
If YES, which rooms? ______________________________________________________
2 | CDC Legionella Environmental Assessment Form | www.cdc.gov/legionella/outbreak-toolkit/

7. Average length of stay for occupants (check one):
❑ 1 night ❑ 2-3 nights ❑ 4-7 nights ❑ >7 nights
8. Does the facility have emergency water systems (e.g., fire sprinklers, safety showers, eye wash stations)?
❑ YES ❑ NO
If YES, are these systems regularly tested (i.e., sprinkler head flow tests)? ❑ YES ❑ NO
If YES, how often and when was the last test? __________________________________________________
9. Are there any cooling towers or evaporative condensers on the facility premises?
❑ YES ➔ If yes, also complete Appendix B.
❑ NO
10. Are there any whirlpool spas, hot tubs, or hydrotherapy spas on the facility premises?
❑ YES ➔ If yes, also complete Appendix C.
❑ NO
11. Are there any decorative fountains, misters, water features, etc. on the facility premises?
❑ YES ➔ If yes, also complete Section D.
❑ NO
12. Does the facility have centralized humidification (e.g., on air-handling units) or any room humidifiers?
❑ YES ❑ NO
If YES, describe their location and operation:_

13. Has there been any recent (last 6 months) or ongoing major construction on or around the facility premises?
❑ YES ➔ If yes, also complete Appendix E.
❑ NO
14. Has this facility been associated with a previous legionellosis cluster or outbreak?
❑ YES ❑ NO
If YES, please describe number of cases, dates, source if found, and any interventions (immediate and long-term) to prevent
recurrence: _

15. Does the facility have a water safety plan or Legionella prevention program?
❑ YES ❑ NO
If YES, does the facility ever test for Legionella in water samples?
❑ YES ➔ If yes, obtain copies of results ❑ NO
If YES, please describe the plan briefly here (does it include clinical disease surveillance and/or environmental Legionella
surveillance?) and obtain a written copy of the program policy:
_

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4 | CDC Legionella Environmental Assessment Form | www.cdc.gov/legionella/outbreak-toolkit/

16. Describe each building that shares water or air systems, including the main facility

Original
Construction

Later Construction
(renovation,
expansion)

Stories or
Levels

Occupancy rate
(%)*

Daily Census
(yr. avg.)

Use
(List all types of uses)
e.g., occupant rooms, utilities,
heating/AC plant

Building Name
(List main facility building first)
Year Completed

From/To or “N/A”

1.

2.

3.

4.

5.

6.

7.

*[occupancy rate = (# of rooms occupied overnight / total # of rooms) X 100]

#

Rate (%) or “N/A”

#/day or “N/A”

For healthcare, specify:
Outpatient = O
Inpatient (acute) = I
Chronic = C
Intensive care = ICU
Transplant = Tx

Water Supply Source
17. What is the source of the water used by the facility? (Check all that apply)
❑ M
 unicipal water if YES:
Name of supplier ___________________________________________________
How is the municipal water disinfected? (Check one) ❑ Chlorine ❑ Monochloramine ❑ Other ________
Has treatment of municipal water changed in the past year? ❑ YES ❑ NO
If YES, specify _________________________________________________________________________
❑ Non-municipal well if YES:
How is the well water disinfected? (Check one) ❑ Chlorine ❑ Other ___________ ❑ Not disinfected
Is the water filtered onsite? ❑ YES ❑ NO
❑ Other _________________________________________________________________________________
18. Have there been any pressure drops, boil water advisories, or water disruptions (e.g., water main break) to the facility in the
past 6 months? ❑ YES ❑ NO
If YES, describe what happened and which buildings or parts of buildings were affected: ______________________
________________________________________________________________________________________
________________________________________________________________________________________
19. Does the facility monitor incoming water parameters (e.g., residual disinfectant, temperature, pH)?
❑ YES ➔ If yes, obtain copies of the logs ❑ NO
If YES, what is the range of disinfectant residual, temperature, and pH entering the facility? ____________________
________________________________________________________________________________________
Premise Plumbing System
Note: It is important to gain an understanding of where and how water flows, starting where it enters the
facility and including its distribution to and through buildings to the points of use. Understand water processes,
including but not limited to: heating, storage, filtration, UV irradiation, and addition of secondary disinfectants.
Refer to a facility map and blueprints; obtain copies of these and/or draw a diagram and include with the
completed assessment.
20. Are cisterns and/or water storage holding tanks used to store potable water before it’s heated?
❑ YES ❑ NO
21. Is there a recirculation system (a system in which water flows continuously through the piping to ensure constant hot water to
all endpoints) for the hot water?
❑ YES ❑ NO
If YES, please describe where it runs and delivery/return temperatures if they are measured: ___________________
________________________________________________________________________________________
________________________________________________________________________________________
22. Are thermostatic mixing valves used?
❑ YES ❑ NO
If YES, describe where they are located (ideally, mixing valves are close to the point of use): _____________________
________________________________________________________________________________________
________________________________________________________________________________________

5 | CDC Legionella Environmental Assessment Form | www.cdc.gov/legionella/outbreak-toolkit/

6 | CDC Legionella Environmental Assessment Form | www.cdc.gov/legionella/outbreak-toolkit/

23. How is the hot water system configured to deliver hot water to each building?
Type of system
Building name

(e.g., instantaneous
heater, hot water heater
with a storage tank,
solar heating)

Name of system
(e.g., Boiler #1,
Loop #1)

Areas served
(e.g., floor, rooms)

Date of installation

Total capacity
(gallons)

Usual
temperature
setting
(°F)

1.

2.

3.

4.

5.

6.

7.

Comments/notes: _________________________________________________________________________________________________________________
______________________________________________________________________________________________________________________________
______________________________________________________________________________________________________________________________

24. What is the maximum hot water temperature at the point of delivery permitted by state / local regulations?
_______ °F or _______ °C
25. Are hot water temperatures ever measured by the facility at the points of use?
❑ YES ➔ If yes, obtain copies of the temperature logs
If YES, what is the lowest documented hot water temperature measured at any point within the facility?
_______ °F or _______ °C documented on (Month/Date/Year) ______/______/______
❑ NO
26. Are cold water temperatures ever measured by the facility at the points of use?
❑ YES ➔ If yes, obtain copies of the temperature logs
If YES, what is the highest documented cold water temperature measured at any point within the facility?
_______ °F or _______ °C documented on (Month/Date/Year) ______/______/______
❑ NO
27. Are the potable water disinfectant levels (e.g., chlorine) ever measured by the facility at the points of use?
❑ YES ➔ If yes, obtain copies of the logs
If YES, how often are they measured? ________________________________________________________________
If YES, list the range of disinfectant residuals __________________________________________________________
❑ NO
28. Does the facility have a supplemental disinfection system for long term control of Legionella or other microorganisms?
❑ YES ❑ NO
If YES, obtain SOPs for routine use and maintenance as well as maintenance logs and records of disinfection levels, and
complete the table:
Buildings with
supplemental disinfection

Type of system
(e.g., chlorine, chlorine dioxide,
copper-silver)

Date installed

Describe any maintenance
in the past year
(include routine and emergency)

Comments/Notes: _________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
29. Please describe any maintenance (either routine or emergency) carried out on the potable water system in the past year. Obtain
records/SOPs if available. ___________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________

7 | CDC Legionella Environmental Assessment Form | www.cdc.gov/legionella/outbreak-toolkit/

8 | CDC Legionella Environmental Assessment Form | www.cdc.gov/legionella/outbreak-toolkit/

30. Measured Water System Parameters (see instructions on p. 1)
Copy from table for question 23 (p. 6)

Part of system
(Central heater/ boiler=C

Name of system
Building name

(e.g., incoming water,
Boiler #1, Loop #1)

Proximal
occupant room=P
Distal occupant room=D)

Sampling site
(e.g., heater #1,
hot water tap
in room #436)

Free
chlorine
(ppm)

pH

Maximum
measured
temperature
(°F)

Time to reach
max temp
(min)

APPENDIX A. HEALTHCARE FACILITIES
Note: Complete for all healthcare facilities, including but not limited to hospitals, long term care/rehab/assisted
living/skilled nursing facilities, or clinics.
1. Type of healthcare facility (check all that apply):
❒❒ Acute care hospital
If YES, does the facility have a solid organ or bone marrow transplant program?
❑ YES ❑ NO
❒❒ Long term care facility (i.e., nursing home, long term acute care)
❒❒ Rehabilitation facility or other skilled nursing care
❒❒ Assisted living facility
❒❒ Outpatient surgical center
❒❒ Other outpatient clinic (describe): __________________________________________________________________
❒❒ Other healthcare facility (describe): _________________________________________________________________
2. Number of beds: ___________
3. Are ice machines used to provide ice for patient consumption or processing medical equipment?
❑ YES ❑ NO
If YES, list manufacturer and model or catalog number: _____________________________________________________
4. Has this facility experienced previous Legionnaires’ disease cases that were “possibly” or “definitely” facility-acquired?
❑ YES ❑ NO
If YES, describe (e.g., number of cases, dates): ___________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________

A-1 | CDC Legionella Environmental Assessment Form | Appendix A: Healthcare Facilities

B-1 | CDC Legionella Environmental Assessment Form | Appendix B: Cooling Towers and Evaporative Condensers

APPENDIX B. COOLING TOWERS AND EVAPORATIVE CONDENSERS

Note: It is important to gain an understanding of where the cooling towers are located, how they work, and how they are maintained. Cooling towers
are frequently maintained by an outside contractor, and you may need to contact them directly if facility management does not have an in-depth
knowledge of these systems. Request copies of the maintenance logs.
1. List all cooling towers and evaporative condensers on the facility premises:
Name of device
(e.g., CT1)

Date Installed

Manufacturer

Location of device

Distance to nearest air
intake*/location of the air
intake/ passive or forced

Drift
eliminators
used?

Party responsible for
maintenance

(Y/N)

*intakes to air handling units (AHUs)

2. List details of how each cooling tower is chemically disinfected:
Name of device from
Table 1
(e.g., CT1)

List type/name of
bactericide(s) used

Range in which the bactericide(s)
is regularly maintained
(e.g., 5–10 ppm)

Schedule and method
of adding bactericide
(e.g., daily, weekly, as needed,
automatic, by hand)

Are cooling towers turned off
at any time?
(e.g., seasonally) (Y/N)
If yes, include schedule

B-2 | CDC Legionella Environmental Assessment Form | Appendix B: Cooling Towers and Evaporative Condensers

3. List recent (last 6 months) special (non-routine) treatments, maintenance, or repairs to cooling devices:
Name of device from Table 1
(e.g., CT1)

Action taken

Date

Comments

4. Does the cooling tower water come from a branch of the potable water system inside the facility?
❑ YES ❑ NO
If YES, are backflow prevention devices in place to ensure cooling tower water is not introduced into the potable water system?
❑ YES ❑ NO
If NO, what is the source of water for the cooling towers and evaporative condensers? _____________________________________________________________
_____________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________
5. Can any windows in any occupant rooms or common areas be opened? ❑ YES

❑ NO

If YES, describe which rooms or which buildings have windows that can be opened: _______________________________________________________________
_____________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________
_____________________________________________________________________________________________________________________________

APPENDIX C. WHIRLPOOL SPAS, HOT TUBS, AND HYDROTHERAPY SPAS
Note: Do NOT complete Appendix C for Jacuzzis or whirlpool baths that are filled from the tap and drained after
each use. In many jurisdictions, whirlpool spas are publicly permitted and inspected by the local health authority.
An environmental health specialist with expertise in pool and spa inspection should participate in assessment of
spas and will be aware of local regulations and enforcement powers, as well as have access to a pool sampling
kit. Request copies of the last inspection report as well as routine maintenance logs.
1. Who performs the spa maintenance (e.g., on-site facilities management, name of outside contractor)? ___________________
2. Describe each whirlpool spa and how it is disinfected:
Spa Questions

Spa Descriptor/Location (e.g., main pool, private room #)

Indoor or outdoor?
Max. bather load
Filter type
S = sand
DE = diatomaceous earth,
C = cartridge
Date filter was last changed
Date of last filter backwash
Compensation tank present?
Type of disinfectant used
(include chemical name,
formulation, and amount used)
Current measured disinfectant
level
(e.g., free chlorine, bromine) (ppm)
Current measured pH
Method used for adding
disinfectant
(e.g., automatic feeder, by hand)
Method used for monitoring
and maintaining disinfectant
and pH levels
(e.g., automatic controllers)
Date last drained and scrubbed
Was there a recent disinfectant
“shock” treatment?
Operating as designed and in
good repair?
If no, describe issues.

C-1 | CDC Legionella Environmental Assessment Form | Appendix C: Whirlpool Spas, Hot Tubs, and Hydrotherapy Spas

APPENDIX D. OTHER WATER FEATURES
Note: Complete for decorative fountains, water walls, recreational misters, etc. This can also be modified for
industrial use water. If SOPs and/or maintenance logs exist, request copies.

Water Feature Questions

Water Feature Descriptor/Location
(e.g., lobby fountain, cabana misters)

Indoor or outdoor?

Source of water

Operates continuously (C) or
intermittently (I)
Presence of a heat source?
(e.g., incandescent lighting)
Type of disinfectant used
(include chemical name,
formulation, and amount used)
Current measured disinfectant
level
(e.g., free chlorine, bromine)
(ppm)
Current measured pH

Is there a maintenance
protocol?
Date last cleaned

Operating as designed and in
good repair?
If no, describe issues.

D-1 | CDC Legionella Environmental Assessment Form | Appendix D: Other Water Features

APPENDIX E. RECENT OR ONGOING MAJOR CONSTRUCTION
1. Describe in general the extent of the construction: _________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
2. Was temporary water service provided to the new construction area (i.e., separate meter)?
❑ YES ❑ NO
If YES, describe: _________________________________________________________________________________
______________________________________________________________________________________________
3. Has jack-hammering or pile-driving been used during the construction process?
❑ YES ❑ NO
If YES, list dates and locations: _______________________________________________________________________
______________________________________________________________________________________________
4. Have there been disruptions or changes to the existing potable water system during the construction?
❑ YES ❑ NO
If YES, describe: _________________________________________________________________________________
______________________________________________________________________________________________
5. Has the potable water changed in terms of taste or color during the construction process?
❑ YES ❑ NO
If YES, describe the changes including when they started and ended: ___________________________________________
______________________________________________________________________________________________
6. Is there a standard operating procedure (SOP) for shutting down, isolating, and refilling/flushing for water service areas that
have been subjected to repair and/or construction interruptions?
❑ YES ❑ NO
If YES, briefly describe the steps used in the SOP (attach a copy if possible): ______________________________________
______________________________________________________________________________________________
7. Was the potable water system flushed before occupying the new building space?
❑ YES ❑ NO
If YES, what period of time passed between flushing and when the building was occupied? ___________________________
______________________________________________________________________________________________
8. Complete table on next page.

E-1 | CDC Legionella Environmental Assessment Form | Appendix E: Recent or Ongoing Major Construction

E-2 | CDC Legionella Environmental Assessment Form | Appendix E: Recent or Ongoing Major Construction

8. Complete the table below:

New Building/Wing Name
or Remodeled Area

Date
construction
began

Estimated
date of
completion

Date water
service
began or
restarted*

Relationship to
existing potable
water system

Stories and
Square Feet
Involved

Independent=I
Extension of
existing system=E

(# and Ft2)

*If remodeling of existing structure, include water shut-down date and re-start date.

Uses

(e.g., rooms, dining, recreation,
utilities)
For healthcare:
Inpatient = I
Outpatient = O
Both = B
Intensive Care = ICU
Transplant = Tx

Date
occupants
began
occupying
new or
remodeled
building

Floors
currently
occupied