Emergency flushing and disinfection of a building’s water systems is important after notification that there has been a suspected case of Legionnaires’ disease, verified by health officials or after a positive test for Legionella bacteria in a building’s water system has been confirmed by lab testing.
When conducting an emergency Legionella response, the Centers for Disease Control and Prevention (CDC) recommends several key actions be taken to identify the source of the outbreak and prevent further spread. These actions include assessing the building’s water system, identifying potential sources of bacteria growth and exposure, collecting environmental samples and implementing emergency control measures.
The CDC also emphasizes the importance of documenting and communicating all activities and findings with a multifaceted approach focusing on clinical and environmental testing, as well as a reassessment of the water management program. The facilities’ water management team usually does these activities. If a facility does not have a water management plan, it should consider developing one.
Included in that multifaceted response, after initial testing, is an emergency flushing and disinfection procedure that should be done in an orderly and timely manner. Prior to flushing and disinfection, it is especially important to have an emergency flushing and disinfection plan that calls for testing before these procedures.
Having a plan in place will ensure it is done correctly, and this gives a baseline for the efficacy of remediation actions. All activities should be documented to show they were done under the emergency plan.
The types of water systems that may need to be assessed, flushed and disinfected in a building or on a site include the following building water systems:
- The water utility service pipe, domestic cold water storage and distribution system,
- Domestic hot water distribution, storage and recirculation system,
- Condenser water and cooling tower systems,
- Plumbing fixtures such as showers, sinks, whirlpool baths, pressure-assist or flushometer-type water closets that can aerosolize water,
- Humidification water systems,
- Decorative fountains and water features,
- Swimming pools and spas,
- Irrigation systems,
- Other building water systems.
A positive Legionella test in the water system does not always lead to illnesses if the levels are low. Still, it warrants following up to determine the cause of the elevated bacteria levels. This should include performing a risk assessment to evaluate the building water systems and premises, looking for potential hazards and areas that are not within the temperature or water treatment chemical residual target control limits. If these areas are within water management plan control limits and bacteria are still present, the water management team should look at adjusting the plan based on input from water management professionals.
Things the water management team should look for include:
1. Verifying water treatment chemical residuals at the building service entrance to check for the source/water utility entering the building and checking at pre-determined, remote points-of-use to look for water treatment chemical degradation within the building.
2. Looking for aging water or dead legs within the building at pre-determined locations per the water management plan.
3. Collecting water samples for culture and polymerase chain reaction (PCR) testing per the water management plan.
4. Checking water treatment, pumps and filters for water features.
5. Checking maintenance records for swimming pools and spas.
6. Ensuring the continuous operation of the pool and spa pump, filter and chemical feed units.
7. Checking for dead legs in the building water piping system.
8. Checking for water temperatures in the system conducive to Legionella bacteria growth.
9. Looking for sources of aerosolized water (inhalation risks).
10. Looking for stand-by equipment that is stagnant.
Epidemiology
If the building is identified as a potential source of Legionellosis related to someone who became ill and was a current or former building occupant, there may already be medical professionals and health department officials involved in performing an epidemiological survey of the patient and the facility, especially if more than one person associated with the building has been confirmed to have Legionellosis within a specified period.
Epidemiology can be described as the study and analysis of who, what, where, when, why and how a disease is transmitted to humans. An epidemiological survey can include determining the causative micro-organism (Legionella bacteria) and how it was transmitted to patients by interviewing them about where they were during the incubation period for Legionella to look for where they may have been exposed. Incubation is generally two to 10 days or, if in a hospital/healthcare setting, two to 14 days.
Further epidemiological investigation includes looking for where the bacteria could grow in the building’s water systems. This includes determining where or what portions of the building patients visited and how the bacteria could be transmitted or aerosolized and transmitted to or inhaled into a person’s lungs, where the bacteria can grow and cause Legionnaires’ disease.
Legionella bacteria can be detected using several types of tests, including clinical tests on patient samples and environmental tests on water sources in a building. Clinical tests include culture of lower respiratory secretions and the Legionella urinary antigen test. Environmental testing involves culture growth and takes several days to get results through PCR methods.
Culture is considered the gold standard for Legionella detection, while the urinary antigen test is a rapid and convenient method for detecting Legionella pneumophila serogroup one. If a patient tests positive with a urine antigen test, it would be good to perform a culture test to help determine the source of the Legionella.
Emergency remediation
When a facility is suspected in a Legionella case, it is important to shut down water systems at the facility and determine if evacuation may be necessary until the system can go through the emergency remediation procedure, an assessment of the water management plan to develop an emergency flushing and disinfection plan. The remediation also includes performing culture testing and PCR testing on key locations of the building water system to establish a baseline and see if emergency flushing and disinfection has eliminated the problem.
Sometimes flushing does not help if the source water is contaminated. Contacting the municipal water supplier may be needed if water mains need to be flushed. The water utility may need to develop a water management plan to address aging water issues or other conditions that cause elevated contaminants in the utility water supply.
The source of a Legionella outbreak can be determined with accuracy, like DNA testing, when both the patient and the source environment are tested with a culture test. Once the culture test has determined a match, the source of Legionella bacteria growth and amplification in the building needs to undergo a risk assessment by a person familiar with building water systems and Legionella growth conditions.
The person conducting the risk assessment and sampling should be capable of assessing the system and understanding the system performance requirements. System operating and Legionella control conditions should be addressed in the water management plan. The risk assessor should also understand conditions that lead to bacteriological growth and be able to recommend changes to the plan to minimize growth and aerosolization risks.
The emergency remediation contractor or risk assessor should be familiar with Legionella bacteria growth temperatures and look for them in the system operation temperatures and the environment, or elsewhere in the water system where the bacteria can grow and be aerosolized. They should understand the bacteria’s nutrient sources (in the pipe scale and biofilm) and the water quality/chemistry in which Legionella bacteria can thrive.
They should also understand how water treatment chemicals dissipate over time with water age and be able to record water temperatures and measure the level of water treatment chemical residuals in accordance with the water management plan.
‘Prevention rather than cure’
The American Society of Sanitary Engineering has a motto, “Prevention rather than Cure.” For Legionnaires’ disease, this involves epidemiology to research how Legionella bacteria grow in a building water system, identify where it can be aerosolized and transmitted to humans, and intervene to eliminate growth and aerosolization before people become infected.
It is important to teach building maintenance personnel how to maintain systems in a way that prevents bacterial growth and aerosolization. Testing for Legionella is part of the epidemiological process to determine when someone is sick, but monitoring building water system conditions and following protocols to prevent bacterial growth in a building water system are extremely important.
In a typical case, after a patient becomes sick and a test is done to determine they have Legionnaires’ disease, the doctors follow protocols for interviewing patients to see where they have been during the incubation period from the time of exposure to the first symptoms. So, if an active person who travels a lot gets sick, the potential exposure sites in the incubation period can be many.
If the patient has a compromised immune system, he is generally less mobile and more susceptible to getting Legionnaires’ disease because his immune system cannot fight off invasive micro-organisms fast enough, usually leading to flu-like symptoms and fluid in the lungs or pneumonia. Hospitals, nursing homes, senior apartments and hotels can all have higher-risk guests or building occupants. Risk factors for getting Legionnaires’ disease are age, smoking, cancer treatment, organ transplants and other medical issues that weaken the immune system.
When someone notifies the building of a potential Legionella issue, the building’s water management team should be quickly assembled to follow its emergency remediation procedures outlined in the water management plan for the building. If no emergency remediation procedure exists, a plan should be developed. Part of the water management plan can also be a spokesperson who addresses the press with an outline of the emergency flushing and disinfection or remediation procedures being taken and basic facts about Legionnaires’ disease growth and transmission.
Code requirements for flushing and disinfection
• The 2024 International Plumbing Code
The 2024 International Plumbing Code, Chapter 6, Water Supply & Distribution, Section 610.1 states:
“610.1 General
“New Potable water Systems shall be purged of deleterious matter and disinfected prior to utilization. The method to be followed shall be that prescribed by the health Authority or water purveyor having jurisdiction or, in the absence of a prescribed method, the procedure described in either AWWA C651, or AWWA C652, or as described in this section. This requirement shall apply to ‘on-site’ or ‘in-plant’ fabrication of a system or to a modular portion of a system.
“The pipe system shall be flushed with clean, potable water until dirty water does not appear at the points of outlet.
“The system of parts thereof shall be filled with a water/chlorine solution containing not less than 50 parts per million (50/mg/l) of chlorine and the system or part thereof shall be valved off and allowed to stand for 24 hours; or the system or part thereof shall be filled with a water/chlorine solution containing not less than 200 parts per million (200/mg/l) of chlorine and allowed to stand for 3 hours.”
• The 2024 Uniform Plumbing Code
The 2024 Uniform Plumbing Code, Chapter 6, Water Supply & Distribution, Section 609.10 states:
“609.10 Disinfection of Potable Water System
“New or repaired potable water systems shall be disinfected prior to use where required by the Authority Having Jurisdiction. The method to be followed shall be that prescribed by the Health Authority or, in case no method is prescribed by it, the following:
“1. The pipe system shall be flushed with clean, potable water until potable water appears at the point of the outlet.
“2. The system or parts thereof shall be filled with a water-chlorine solution containing not less than 50 parts per million of chlorine and the system or part thereof shall be valved off and allowed to stand for 24 hours; or, the system or part thereof shall be filled with a water-chlorine solution containing not less than 200 parts per million (200/mg/l) of chlorine and allowed to stand for 3 hours.
“3. Following the allowed standing time, the system shall be flushed with clean, potable water until the chlorine residual in the water coming from the system does not exceed the chlorine residual in the flushing water.
“4. The procedure shall be repeated where it is shown by a bacteriological examination made by an approved agency that contamination persists in the system.”
The model plumbing code sections require that potable water systems be flushed and disinfected before putting them into service. Both model codes provide general requirements for flushing and disinfection according to the Authority Having Jurisdiction (AHJ) or the appropriately referenced industry standard or the prescribed method in the code. The codes do not provide a detailed procedure for performing and documentation of emergency flushing and disinfection procedures for building water systems, unless the AHJ requires it.
The code does not specifically require a water management plan or cover steps that should be in the water management plan, such as sampling/testing source water for Legionella and other micro-organisms and documenting the results before flushing, recording water treatment chemical residual testing, detailed steps for a flushing procedure to purge the piping of contaminants, the proper disinfection procedure to avoid excessive water treatment chemical levels that can corrode or damage the piping system, then post-disinfection flushing and post-remediation testing and documentation to validate the procedure was effective.
If the source water is extremely contaminated because of water age and decayed disinfectant residuals, then flushing and disinfection will not resolve the issue.
The American National Standards Institute (ANSI) and the American Water Works Association (AWWA) Standard ANSI/AWWA C651: Disinfection of Water Mains and ANSI/AWWA C652: Disinfection of Storage Facilities have been referenced in the International Plumbing Code and the Uniform Plumbing Code and are often referenced in construction specification documents for disinfection of building potable water systems.
However, these standards were recently revised to say they are not intended or appropriate for building potable water systems. This is because they do not address piping systems smaller than 4 inches in diameter. Most plumbing and building water system pipes in typical building water systems are not of cast iron or ductile iron material and are smaller than the 4-inch diameter pipe, the smallest pipe listed in the standard.
The AWWA C651 and C652 standards were developed many years ago for using disinfectant levels intended for cast iron or ductile iron water mains that have very thick pipe walls. The minimum chemical levels they recommend for disinfection are typically too high for most domestic water distribution pipe materials; the high water treatment chemical levels have been known to damage building plumbing systems. The main problem is that there is no maximum water treatment chemical level listed in the standard, only a minimum level and contact time.
A new AWWA technical report that is not a standard written in mandatory language and does not address emergency flushing and disinfection of building water systems, has lower minimum levels of water treatment chemicals for disinfecting building water systems. Still, the new report repeats the same problem, and it does not address or provide any guidance on maximum water treatment chemical levels.
It is up to the water management team to provide directions and guidance on the maximum water treatment chemical levels for a given building, based on the pipe materials and equipment in that building, for the emergency flushing and disinfection plan.
Owners/operators/water management plan team members should pay close attention to developing their emergency disinfection plans and address controlling and monitoring the maximum water treatment chemical levels and the minimum disinfection contact time. They should also require quickly flushing the higher levels of disinfectant from the piping system so as not to damage the plumbing systems with excessive chemicals.
Plumbing system failures
In recent years, I have travelled across North America investigating plumbing system failures in all building types with various piping materials, where the piping systems in new buildings were corroded and oxidized and were failing because of excessive water treatment chemical exposure. Some cases exceeded $100 million in damage claims for a new high-rise building.
Some contractors noted they just hooked up the chlorine barrels and the pumps to the piping system, turned the pumps on and let them run, so during times when there was little to no flow in the plumbing pipe, 100% of the water treatment chemicals were pumped into the piping system. There was no pre-mixing or flow proportioning with meters and chemical injection pumps for the disinfection procedure to prevent excessive chemical levels and damage to the piping during disinfection and flushing.
A few contractors have told me that in the past, they would ignore the disinfection requirement in the construction specifications and the plumbing code during construction and flush water through the system to save money.
Awareness of Legionnaires’ disease is on the rise, so owners are requiring proof of the flushing and disinfecting procedures, and there has been a rise in the number of new piping systems damaged by poor disinfection techniques.
The water management plan should guide how to prepare building plumbing for disinfection by performing baseline testing first, then flushing the high levels of contaminants from the piping system, then disinfecting with the appropriate concentration of water treatment chemicals and contact times, then flushing the disinfectant chemicals out of the building water system and documenting the entire process.
Next month, we will continue with Part 2, detailing how a water management plan should address emergency remediation that includes testing, flushing, disinfecting, post-disinfection flushing then validating testing.
