As facility managers and building owners know, ensuring high water quality within buildings is crucial for both regulatory compliance and occupant safety. While internal water management is often prioritized, the quality of water entering the facility is equally critical. Monitoring this incoming water can significantly mitigate risks associated with waterborne pathogens, particularly Legionella, the bacteria responsible for Legionnaires’ disease. By maintaining high water quality standards, facilities can stay compliant with health regulations and protect the well-being of people. .

Understanding the Importance of Incoming Water Quality

The quality of incoming water directly influences a facility’s overall water management. Water sourced from municipal supplies or wells can carry various contaminants, including Legionella, that may proliferate within the building’s water system if not properly managed. Regular monitoring and management of incoming water are essential steps in preventing contamination and minimizing the risk of Legionnaires’ disease and other waterborne illnesses. If substantial construction or water pressure shock results in the release of biofilm into the water and a building’s plumbing system, routine Legionella testing would likely be ineffective to promptly notify the facility due to its inability to be conducted on multiple occasions throughout the day.

Six Key Benefits of Monitoring Incoming Water Quality:

  1. Early Detection of Contaminants Monitoring water quality allows for the early identification of potential contaminants, including bacteria such as Legionella. This early detection enables facilities to take prompt action before these contaminants can affect the building’s water supply and pose a health risk.
  2. Compliance with Health Standards Adhering to recommended water quality parameters ensures that facilities remain in compliance with health regulations aimed at preventing waterborne diseases like Legionnaires’ disease. This adherence minimizes the risk of legal issues and helps protect public health.
  3. Maintaining System Efficiency Effective water quality management helps maintain the efficiency and longevity of plumbing and heating systems. It also prevents issues such as scaling and corrosion, which can arise from poor water quality and create environments conducive to Legionella growth.
  4. Protection Against Legionnaires’ Disease Proactive monitoring of water quality is crucial in preventing the growth of Legionella. This bacterium thrives in specific water conditions, and regular monitoring can help maintain an environment that is inhospitable to its proliferation, thereby reducing the risk of Legionnaires’ disease.
  5. Enhancing Overall Safety Regular monitoring and management of water quality reduces the risk of Legionella and other waterborne pathogens. This vigilance supports a safer environment within the facility and protects public health.
  6. Optimizing Facility Operations By maintaining high water quality, facilities can ensure the smooth operation of systems that rely on water. This optimization can lead to cost savings, improved operational efficiency, and a reduced risk of Legionella outbreaks.

Key Parameters to Monitor in Incoming Water

To safeguard against contamination and maintain compliance, monitoring several key water quality parameters is essential. These parameters are recognized by leading health and safety organizations as critical for ensuring safe water quality in buildings and preventing the growth of Legionella.

ParameterASDWA 2020CDC 2021VHA 2021Joint Commission EC.02.05.02
Disinfectant ResidualsXXXX
Suspended/Dissolved SolidsX

1. pH Levels

The pH level of water is a critical indicator of its corrosiveness and potential to harbor pathogens like Legionella. Both highly acidic and highly alkaline water can damage plumbing and encourage the growth of bacteria. Monitoring pH helps in maintaining it within an optimal range, typically between 6.5 and 8.5.

2. Temperature

Temperature is a crucial factor in controlling the growth of Legionella, which thrives in temperatures between 20°C and 45°C (68°F to 113°F). Keeping water outside this range can help mitigate the risk of Legionella proliferation. Monitoring incoming water temperature allows facilities to take corrective actions if temperatures fall within the risk zone.

3. Disinfectant Residuals

Maintaining appropriate levels of disinfectants, such as chlorine or chloramine, is essential to keep the water free from microbial contamination, including Legionella. Monitoring these residuals ensures that the water retains its disinfectant properties as it enters the facility, providing a first line of defense against pathogens.

4. Water Hardness

Hardness, typically caused by calcium and magnesium ions in the water, can lead to scaling in pipes and equipment. This not only reduces system efficiency but also creates an environment conducive to biofilm formation, which can harbor Legionella. Regular monitoring can help manage and mitigate these risks.

5. Turbidity

Turbidity refers to the cloudiness of water caused by suspended particles. High turbidity can shield bacteria from disinfectants and is often an indicator of higher levels of organic matter, which can serve as nutrients for microbial growth, including Legionella. Monitoring turbidity can provide insights into the overall quality of incoming water.

6. Suspended or Dissolved Solids

Suspended solids include particles like silt, sand, and minerals that are not dissolved in the water. High levels can contribute to turbidity and provide a medium for bacteria like Legionella. Dissolved solids include minerals and salts that can impact water taste and hardness. Monitoring these can help maintain water clarity and prevent system inefficiencies.

Steps to Implement Effective Water Quality Monitoring

  1. Assessment of Incoming Water Sources: Evaluate the sources of water entering your facility and identify potential risks associated with each, especially the risk of Legionella contamination.
  2. Develop a Monitoring Plan: Create a plan that outlines the parameters to be monitored, the frequency of monitoring, and the methods to be used to detect Legionella and other contaminants.
  3. Install Monitoring Equipment: Use reliable and accurate equipment to measure the critical water quality parameters identified, ensuring they are capable of detecting Legionella.
  4. Regular Data Review: Establish a routine for reviewing monitoring data to quickly identify any deviations from acceptable levels and take immediate action to control Legionella and other pathogens.
  5. Corrective Actions: Define and implement corrective actions when monitoring indicates water quality issues that could lead to Legionnaires’ disease.
  6. Documentation and Reporting: Maintain detailed records of monitoring results and actions taken to demonstrate compliance with health standards and support continuous improvement efforts in Legionella management.


Monitoring the quality of water entering your facility is a vital component of a comprehensive water management strategy aimed at preventing Legionnaires’ disease. By proactively managing key water quality parameters, facilities can not only comply with health regulations but also ensure the safety and efficiency of their water systems. This vigilance in water quality monitoring serves as a foundational step in reducing the risk of Legionella and other waterborne pathogens, protecting both building occupants and infrastructure.

By focusing on these six crucial reasons for monitoring water quality, facilities can maintain a safe, efficient, and compliant environment. Regular and proactive monitoring of incoming water is essential for safeguarding against potential hazards and ensuring the long-term integrity of the facility’s water systems, ultimately protecting against the threat of Legionnaires’ disease

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