Risk Assessment

Risk Assessment Services | Water Management Programs

What is a Risk Assessment?

Risk assessments are increasingly being used worldwide as an essential part of a non-potable and potable drinking water quality surveillance and control program. The World Health Organization (WHO) in its latest guidelines states “the most effective means of consistently assuring the safety of a drinking water supply is World Health Organization Logothrough the use of a comprehensive risk assessment and risk management approach that encompasses all steps in water supply from catchment to consumer”.

Risk assessment is a proactive approach to identify the risks (potential failures of standards and risks to human health and safety) and to take action to control those risks through a multiple barrier approach (for example, treatment of the source water and management of the distribution network to prevent contaminants entering the supply system, all the way through point of use or point of dispense). Terra Marra International provides these comprehensive Risk Assessment Services

Elements of a Waterborne Pathogen Risk AssessmentRisk Assessment Services and Water Management Programs

  • A list of water services plant and outlets.
  • Inspection of the facility to assess cleanliness, general condition, and compliance with standard operating procedures.
  • Production of water system schematics.
  • Samples for the presence of Legionella bacteria, or other waterborne pathogens, from various locations within the down service water systems (showers, taps, etc.) or from evaporative cooling systems.
  • Samples for microbial analysis from various locations within the down serv­ice water systems (showers, taps, tanks, etc.) or from evaporative cooling systems.
  • Temperature measurements taken from various locations within the down service water systems (showers, water heaters, taps, tanks, etc.).
  • pH measurements taken from various locations within the down service water systems (showers, taps, tanks, etc.) or from evaporative cooling systems.
  • Identification of sources of risk.
  • Review of previous test results for the evaporative cooling system and any other risk systems tested.
  • Numerical assessment of level of risk.
  • Review of the existing System of Legionella Control to assess compliance with best-practice guidance or regulations, where applicable.
  • Documentation of procedures and practices.

When to Consider a Risk Assessment:Risk Assessment Services

  • It has been more than 2 years since the last risk assessment.
  • There have been changes or alterations to the plumbing or water distribution system.
  • The building/facility use has changed.
  • There is new information about risks or control measures.
  • Checks indicate that control measures are no longer effective.
  • A case of Legionnaires’ Disease (Legionellosis) is associated with the system.

Risk Factors:

Implementing a corporate wide policy for waterborne pathogens risk reduction is challenging for building and facility water system owners/operators. While a corporate policy for managing the risk is prudent, application of such a policy should not be wholly applied across all buildings/facilities or site locations because not all water systems are equal or operated the same. Implementation starts with a plan that involves a multidisciplinary team including third party consultation Risk Assessment Servicesand expertise, such as Terra Marra International.

The risk of a waterborne pathogen(s) or legionellosis is a function of many factors. These factors can be grouped into three categories, that include:

  • Proliferation Potential
  • Aerosol Exposure
  • Population Susceptibility

Proliferation potential refers to factors such as water stagnation, water temperature, biocide use, water pH, biofilm accumulation, cleaning and disinfection procedures, source water quality, and control & monitoring methods.

The assessment of aerosol exposure is focused on the production, release and dissemination of small water droplets. While many of the well-publicized, mass cases of Legionnaires’ disease have had their origins in cooling towers, it is thought that the vast majority of sporadic cases are coming from domestic building water systems, especially where a spray may be generated from items such as showers, spray faucets, sidewalk or salad bar misters, or ornamental fountains.

Population susceptibility assessment can be more of a qualitative issue since susceptibility to waterborne pathogens is
related to factors such as age and health. Also, information is this area may be guarded or not easily accessed. However, assessing the population as a whole can make a reasonable estimation of risk for this category with factors such as population proximity to the facility water system and the numbers of people exposed to the system.

Principles of a Water Management Program:Water Management Programs

  • Analysis of Building or Facility Water Systems: Conduct a systematic analysis of hazardous conditions in the building or facility water systems
  • Control Locations: Determine the locations in the system where control measures are required.
  • Control Limits: For each control measure at each control location established in Control Locations, determine the limits, including but not limited to a maximum value, minimum value or range within which a chemical or physical parameter must be monitored and maintained in order to reduce hazardous conditions to an acceptable level.
  • Monitoring: Establish a system for monitoring the parameters associated with the control limits established previously.
  • Corrective Actions: Establish the corrective action(s) to be taken when monitoring indicates that the control parameters are outside the established control limits.
  • Confirm Program Implementation: Establish procedures to confirm that all the program elements are being implemented as designed.
  • Documentation and Recordkeeping: Establish documentation concerning all procedures and maintain records appropriate to these principles and their application.

Water Management Programs


ASHRAE Standard 188 Approved:ASHRAE advances the arts and sciences of heating, ventilation, air conditioning and refrigeration to serve humanity and promote a sustainable world.

Legionellosis Standard Provides Guidance On Risk Management Requirements
Atlanta – Long awaited industry guidance on Legionellosis is now available in a new standard from ASHRAE. The document establishes minimum Legionellosis risk management requirements for building water systems.

“The industry interest and input into developing this standard has been tremendous,” Presidential Member Tom Watson, chair of the committee that wrote the standard, said. “With 8,000 to 10,000 cases of Legionnaires’ Disease reported each year in the United States, and with more than 10 percent of those cases fatal, it is vital that we set requirements to manage risk of this bacteria.”

Legionella can also cause a less-severe influenza-like illness known as Pontiac Fever. Most cases of Legionellosis are the result of exposure to Legionella associated with building water systems, according to Watson.

ANSI/ASHRAE Standard 188-2015, Legionellosis: Risk Management for Building Water Systems, is intended for use by owners and managers of human-occupied buildings and those involved in the design, construction, installation, commissioning, operation, maintenance and service of centralized building water systems and components.

Publication of the standard coincides with ASHRAE’s 2015 Annual Conference taking place June 27-July 1, in Atlanta.

Specific requirements in the standard include:

  • Minimum Legionellosis risk management requirements for buildings and their associated potable and non-potable water systems.
  • Establishment by building owners of a Program Team and (in turn) a Water Management Program for which they are responsible in order to comply with the standard.
  • Provision of specific and detailed requirements for what Legionellosis control strategies must accomplish and how they are to be documented – but, does not provide (or place restrictions on) what specific strategies are to be used or applied.

Standard 188 consists of normative sections followed by normative and informative appendices. The normative sections and normative appendices specify the requirements to comply. The informative appendices and informative references are provided for guidance.

Click here to read the full release from ASHRAE.org

ASHRAE, founded in 1894, is a global society advancing human well-being through sustainable technology for the built environment. The Society and its more than 50,000 members worldwide focus on building systems, energy efficiency, indoor air quality, refrigeration and sustainability. Through research, standards writing, publishing, certification and continuing education, ASHRAE shapes tomorrow?s built environment today.


For more information, Contact Us Here or at 866-962-8800 or via email at info@terramarra.com