Much has already been said about the safety improvements homeowners and business owners can anticipate by switching from traditional water heaters to tankless models. Usually the discussions have revolved around the half a million scald or burn incidents happening every year, many caused by overheated tap water from an old or uncalibrated water heater. According Read more
Much has already been said about the safety improvements homeowners and business owners can anticipate by switching from traditional water heaters to tankless models.
Usually the discussions have revolved around the half a million scald or burn incidents happening every year, many caused by overheated tap water from an old or uncalibrated water heater. According to the Burn Foundation, more than one-sixth of all childhood hospitalizations from scalds happen because of hot tap water.
That said, another threat endangers those who use both residential and commercial tank heaters: Legionnaires’ disease. What causes Legionnaires’ bacteria to grow and how can traditional tank heaters put your home or business at risk?
“Legionella grow in still warm water.”
What is Legionnaire’s disease?
Legionnaires’ disease is actually a body of diseases – more than 43 according to the U.S. Occupational Safety and Health Administration – all caused by the same bacteria called Legionella. This pathogen grows in still warm water. If inhaled through water vapor, these bacteria could cause fever, pneumonia, comas and even death.
So, how does a standard hot water tank turn into a Petri dish for Legionella? Unfortunately, a few different ways.
How can hot water tanks produce Legionella?
Fiddling with hot water tank temperatures for energy efficiency gains could set off a chain reaction producing Legionella. Many energy experts, including the U.S. Department of Energy, recommend setting hot water tanks to 120 degrees Fahrenheit to shave a few bucks off a home gas bill. Unfortunately, Legionella can survive that temperature and prosper. OSHA recommends keeping tanks at 140 degrees, which effectively neutralizes Legionella-infected water, but hot water at that temperature could easily scald children or seniors with sensitive skin. Either way, water tank owners lose.
“Sediment collecting in water tank can encourage Legionella growth.”
Sediment collecting at the bottom of a dilapidated water tank can also encourage Legionella growth. If tank owners neglect to flush their systems at least once a year to rid systems of calcium carbonate buildup – common in areas with high water hardness – and other debris, Legionella could develop with time.
Legionella also breeds in pipes where stagnant hot water cools below that 120-degree mark. As hot water trapped between a water tank to a faucet or tap cools, it becomes more and more susceptible to infection.
Fight disease with tankless water heaters for your home
Tankless water heaters provide a number of solutions for these problems. First and foremost, automated technology controls hot water temperatures right at the source, so it’s always the perfect temperature: warm enough to prevent waterborne disease, cool enough to avoid scalds and energy-efficient enough to keep monthly bills low.
Point-of-use tankless water heaters not only forego the large cylindrical basin where Legionella can grow, but also reduce the piping needed to deliver water from a utility to the faucet, thus eliminating another threat. Water moves directly from the public system, into the home and right to the tap where it’s heated on demand
.If your hot water heater isn’t working for you, it’s working against you. Choose tankless models to prevent the spread of Legionella, protect your family from overheated water and save money on your energy bill.
A previous article, “Microorganisms in Plumbing Systems”, warned that under certain conditions microorganisms can grow out-of-control in plumbing systems. When this happens, a “biofilm” of microorganisms and acidic enzymes that they secrete can become attached to pipe walls (Figure 1). This can lead to: Increased metals concentration (such as copper, iron, and lead) in the Read more
A previous article, “Microorganisms in Plumbing Systems”, warned that under certain conditions microorganisms can grow out-of-control in plumbing systems. When this happens, a “biofilm” of microorganisms and acidic enzymes that they secrete can become attached to pipe walls (Figure 1). This can lead to:
- Increased metals concentration (such as copper, iron, and lead) in the drinking water that comes in contact with the affected pipe
- Pitting and pinhole leaks in metal pipe
- Increased possibility of water-borne illnesses from microorganisms that are toxic to humans
Stagnating or slow moving water with inadequate disinfection allows microorganisms to grow rapidly. Microorganisms also need surface area to attach to – the more surface area, the more colonies of microorganisms can attach and grow.
This article identifies critical locations in a plumbing system where microbiological growth and biofilm formation tend to start. These locations are important to keep in mind as methods to prevent microbiological growth are discussed in future articles.
Biofilm in a Residential Copper Pipe
The light coating on the pipe in Figure 1 is a biofilm. Not all biofilms look like this. But, the one in Figure 1 is smooth, thick, and tightly adhered to the pipe wall.
The Water Source
A biofilm problem in a building can start with the water source. The water can carry microorganisms into a building’s plumbing system. If conditions are right in the plumbing system, the microorganism population will grow.
When private wells are a building’s water source, microorganisms can enter the well in the groundwater which has had contact with the surrounding soil and sometimes with surface water that has percolated down into the aquifer. Once in the well, microorganisms can form biofilms and attach to screens, casings, and piping. For this reason, wells should be cleaned periodically with high concentrations of chlorine solution. This is called shock chlorination and usually involves a solution of 200 to 300 mg/L free chlorine held in the well for twenty-four hours. Well owners may not realize the importance of this cleaning procedure and may neglect to have it done.
For buildings with water provided by a municipal or community water system, microorganisms are present in the water to varying degrees. In the drinking water industry, the emphasis is on microorganisms that are toxic to humans and can cause illness. However, the absence of illness-causing microorganisms in a water system does not mean that other microorganisms are not thriving. The lowest presence of microorganisms is found in municipal or community water systems where disinfection concentrations are maintained at effective levels and monitored throughout the distribution system. There are some water systems where disinfection is not maintained sufficiently and some where no disinfection is added at all. In those systems, the presence of microorganisms entering a building can be quite high.
The Water Service Line
A building is connected to a water source by means of a water service line. This can be piping between a building and a privately-owned well; or, it can be piping between a building and a water main in a municipal or community water distribution system. The longer that water stays in the water service line, the more likely it is that microorganisms will form biofilms on the pipe walls. This can lead to microbiologically influenced corrosion of the water service line with the effect of increasing metal concentrations in drinking water or creating leaks through holes in the pipe wall. Microorganisms from the biofilms can also be carried away by the passing water and taken into the building’s plumbing system to start new colonies.
Point of Entry Water Treatment
Water treatment is sometimes installed in buildings just as the water piping enters the building. This is called “point of entry” water treatment. Any water treatment device should be considered a critical location for microbiological growth in a water system for three reasons:
- Many water treatment devices include tanks that hold a large volume of water. Depending on water usage in the building, water might stay in a water treatment tank for an extended period of time. This long residence time in slow moving water allows for the growth of microorganisms.
- Along with the large volume of water in water treatment devices comes increased surface area. Many water treatment tanks are filled with particles that perform the water treatment, where the higher the surface area of the particle, the better the treatment. Examples of such particles are sand, ion-exchange resin beads, and granular activated carbon. The increased surface area gives great advantage to the attachment of microorganisms and the development of biofilms.
- Any disinfection in the water that enters most water treatment devices is removed in the device. The disinfection might be removed because that may be the purpose of the water treatment device, like granular activated carbon filters. It might also be removed because the disinfection is used up fighting microorganisms that have already taken up residence in the device. With the disinfection gone, downstream piping is no longer protected against the microorganisms that are carried out of the water treatment device in the flowing water.
Water softening is a type of water treatment device. It is typically installed farther downstream from the building’s point of entry, but all of the problems of microbiological growth discussed above affect water softeners.
In areas of the country where water high in calcium carbonate (also called “hard” water) is used, water softeners are needed to keep calcium carbonate out of hot water systems. This is because calcium carbonate can fall out of the water as solid particles that build up on heating surfaces. The energy required to transfer heat from the heating surface through the increasing layer of calcium carbonate and into the water becomes greater and greater. Therefore, it is more cost effective to remove the calcium carbonate before it enters the hot water system.
Unfortunately, if microbiological growth has occurred significantly in a water softener, the hot water system downstream receives microorganisms in the water and no disinfection to fight them.
Hot Water Systems
Hot water systems have some additional characteristics that encourage the growth of microorganisms. For example, if the storage tank is oversized for routine water usage, water is in the tank for an extended time, creating the conditions for microbiological growth. An oversized hot water storage tank is installed when there is an infrequent but large demand for hot water, such as for filling a large bathtub. When the tub is not in use, water has a long residence time in the tank making it prone to microbiological growth.
For large buildings, hot water recirculation systems are typically used so that hot water will be immediately received at each faucet, no matter how far away from the hot water storage tank. The recirculation system contributes to microbiological growth by adding more residence time and surface area to the plumbing system. It also helps to spread microorganisms from an infected site to other sites that have not yet been infected.
Point of Use Water Treatment
Water treatment devices at or near faucets are referred to as “point of use” water treatment. The same issues of microbiological growth can occur on those devices as discussed above. The good news is that there is little to no piping downstream of the device that can be affected by microbiological growth. The bad news is that the consumer is directly downstream of these devices. For this reason, the manufacturers’ instructions on equipment cleaning and replacement of filters must be followed closely.
Biofilms can form upstream and inside faucets as with any surface area in a plumbing system. Faucets and associated upstream plumbing that are reached a long time after the water has entered the building have a greater potential for microbiological growth. Faucets and associated upstream plumbing that are used infrequently also have a greater potential for microbiological growth.
In a plumbing system, the conditions of water stagnation, high surface area, and lack of disinfection contribute to the possibility that significant microbiological growth and biofilm formation can occur.
This article has discussed critical locations in a plumbing system where microbiological growth and biofilm formation tend to start, beginning at the water source and continuing through the water service line, point of entry water treatment, water softening, hot water system, point of use water treatment, and faucets. These locations are important to keep in mind as methods to prevent microbiological growth are discussed in future articles.
Abigail F. Cantor, P.E., Chemical Engineer
Process Research Solutions, LLC
PO Box 5593
Madison, WI 53705
Process Research Solutions, LLC is an engineering consulting firm specializing in water quality investigations for drinking water and industrial process water.
The company has also developed tools and protocols to proactively monitor and control water quality, lowering the chances of developing serious and expensive issues in water systems.
Data management computer software, My Monitoring Data®, has been developed by Process Research Solutions, LLC so that water quality and water system data can be quickly interpreted and utilized.
Certain plumbing design choices and building contractor practices can promote the growth of microorganisms in new plumbing systems. This can lead to corrosion of metals, increased metals concentration in the drinking water, holes in pipe walls, and waterborne illnesses. Basic steps can prevent the problem from occurring in the first place. INTRODUCTION TO DISASTER Read more
Certain plumbing design choices and building contractor practices can promote the growth of microorganisms in new plumbing systems. This can lead to corrosion of metals, increased metals concentration in the drinking water, holes in pipe walls, and waterborne illnesses. Basic steps can prevent the problem from occurring in the first place.
INTRODUCTION TO DISASTER
The story is repeated over and over. Occupants of a new building notice either discolored water coming from the water faucets or a “rotten egg” odor coming from the hot water.
Typically, what will happen next is that the plumbing contractor, realizing that corrosion is occurring, will pull the sacrificial anode rod from the hot water storage tank. The rod in a hot water storage tank is there to slowly corrode over many years, with the rod’s metallic properties diverting the flow of electrons to sacrifice itself to corrosion and protect the storage tank. But, in these cases, the anode rod has greatly corroded over a few weeks or months. The plumbing contractor will replace the rod, only to see the new rod corrode quickly again.
Stray electrical currents or the connection of dissimilar metals are then blamed for the system-wide corrosion. Wires are added to connect various parts of the piping system for diverting electrons to a different path.
The problem persists.
MICROORGANISMS AT WORK
What most people don’t know is that the problem is of microbiological origin. Microbiologically influenced corrosion (MIC) has not been appropriately understood or acknowledged in the drinking water industry—in municipal water systems or in plumbing systems.
Microorganisms are everywhere, and there are many different types of them. Some directly cause human illness and some do not. All waterborne microorganisms can grow into out-of-control populations when there are long periods of water stagnation or low flow and when disinfection chemicals are in inadequate concentrations. Under such conditions, microorganisms attach to plumbing system surfaces, both metal and non-metal. The microorganisms secrete an enzyme that forms a protective barrier around them, and they begin to multiply. This buildup of enzyme and microorganism colonies on surfaces is called a biofilm.
The biofilm is acidic and can create conditions at the pipe wall that allow metal to corrode. Metals that the plumbing sys- tem is made of, such as copper, iron, and even lead, have been found to corrode and their concentrations found to be increased in the drinking water when biofilms are present. Pinhole leaks in copper pipes have also been found. In addition, lower doses of chlorine and other disinfectants cannot reach the microorganisms protected in the biofilms. Instead, disinfectants get used up by reactions with the surface of the biofilms. This creates the environment for the growth of microorganisms that cause human illness if they are accidentally introduced into the water system.
Once a biofilm is firmly in place in a plumbing system, it is very difficult, if not impossible, to remove. It cannot be flushed with high-velocity water because the required water flows and pressures cannot be achieved in plumbing systems. The biofilm cannot be removed by disinfection because many modern plumbing materials, such as PEX® piping, cannot come in contact with the high concentrations of disinfection that are needed.
PREVENTIVE MEASURES IN PLUMBING DESIGN
Proper plumbing design is the first line of defense against the growth of microorganisms in a plumbing system. In general, in water with low or no disinfection, whenever an excessive quantity of water is stored and excessive surface area is available in the plumbing system, microorganisms can get the upper hand and form biofilms.
Plumbing designers should carefully plan the capacity of the water system. In modern plumbing systems, the high hot waterflow demands of large bathtubs and Jacuzzis control the plumbing system design. This leads to installation of large water softeners and hot water storage tanks which are oversized for typical water usage in the building when the tubs are not in use. This creates a long residence time for water inside the plumbing system.
Another area where biofilm development is typically found is in hot water recirculation systems. In larger residences and buildings, hot water is re-circulated between the faucets throughout the building and the storage tank in order to provide water at the desired elevated temperature immediately when a faucet is opened. The recirculation piping adds extra storage of water and residence time in the plumbing system and helps spread microorganisms from a location of biofilm development to other parts of the hot water system.
Water conservation devices also increase the time that water spends in the plumbing system.
Water treatment devices cause issues in that many remove disinfection from the water, provide a large volume of water storage, and provide greatly increased surface area on the treatment media, such as on physical filters, granular activated carbon, and softener resin.
There is no room in this article to discuss plumbing design details. Just be aware in plumbing design that disinfected water should flow in the plumbing system with minimum residence time and minimum surface area contact.
PREVENTIVE MEASURES DURING CONSTRUCTION
Construction of a building takes months and sometimes over a year or more. During this time, any water that has been introduced into the water service line and the interior plumbing system is stagnating in the pipelines and forming biofilms. Building contractors need to be aware of this. Routine flushing and disinfection of all on-site pipelines should be performed. The disinfection concentration, and even the microbiological activity, can be measured and documented to show that no problems occurred under the building contractor’s watch.
Although there are many details that can help prevent microorganism growth, generally be aware that flushing, disinfection, and monitoring can prevent the growth of microorganisms and the development of biofilms in the piping system.
Everyone involved in the design and construction of buildings should be aware that microorganisms can and do significantly affect water quality in plumbing systems and can even weaken the pipe itself. Modern plumbing systems with large bathtubs, increased use of water treatment devices, materials of construction that cannot come in contact with high disinfection concentrations, and water conservation devices contribute to the likelihood that microorganisms will grow in the plumbing system and form biofilms on pipe and tank surfaces.
Plumbing designers can do their part in preventing the growth of microorganisms and the development of biofilms by minimizing the residence time of water in the plumbing system and the surface area that the water contacts. Building con- tractors can do their part by routinely flushing the pipelines, disinfecting the water, and documenting disinfection concentration and microbiological activity.
Abigail Cantor is the founder of Process Research Solutions, LLC, a chemical engineering consulting firm specializing in drinking water quality issues.
The theme being “All about you”, GF Piping Systems presents itself as a system provider of products for drinking water applications at IFH/Intherm from 8 to 11 April 2014 in Nuremberg. The focus is on system solutions for all aspects of water from abstraction to distribution and all the way to the point of consumption Read more
The theme being “All about you”, GF Piping Systems presents itself as a system provider of products for drinking water applications at IFH/Intherm from 8 to 11 April 2014 in Nuremberg. The focus is on system solutions for all aspects of water from abstraction to distribution and all the way to the point of consumption, as well as the associated living comfort.
Requirements in terms of drinking water hygiene are steadily increasing. In order to reduce health risks from contamination and bacteria for end consumers, the drinking water must be transported with extreme care. Starting with planning and continuing on to installation of the piping system, the highest level of quality must be warranted throughout.
GF Piping Systems meets challenges posed by the new drinking water hygiene regulation with system solutions for drinking water installations and hygiene. On booth 7A.403 at IFH/Intherm GF Piping Systems showcases products for the drinking water distribution in buildings, from proven systems like the JRG Sanipex classic and MT to the innovative diaphragmalysis technology Hycleen Des 30.
Products from GF Piping Systems are valued by building services engineers and operators for their superior quality and easy installation and maintenance. End users appreciate having clean drinking water that meets the highest hygiene standards, as well as having a constant water pressure at every tapping point in the entire building.
As the living comfort is becoming an increasingly important factor in life nowadays, living space is supposed to be practical and comfortable. This includes aspects that people do not primarily perceive. GF Piping Systems makes this apparent to visitors at the IFH/Intherm with a sound booth in which they hear how different connection types and materials affect flow noise.
Global public health organization NSF International creates Hazard Analysis and Critical Control Point (HACCP) training to reduce risk of microbial, chemical and physical hazards in building water systems Global public health organization NSF International has launched a new Building Water Systems Hazard Analysis and Critical Control Point (HACCP) training program for water systems professionals. The Read more
Global public health organization NSF International creates Hazard Analysis and Critical Control Point (HACCP) training to reduce risk of microbial, chemical and physical hazards in building water systems
Global public health organization NSF International has launched a new Building Water Systems Hazard Analysis and Critical Control Point (HACCP) training program for water systems professionals. The training will help safeguard against microbial, chemical and physical hazards associated with premise plumbing, cooling towers and other water systems in buildings.
Training courses will be held in multiple cities across the U.S. Facility managers, water treatment, distribution and plumbing engineers, and occupational safety professionals can register here: www.nsf.org/training-education/all-courses/category/water-wastewater.
Every year, tens of thousands of preventable injuries and deaths are caused by exposure to microbial, chemical and physical hazards from building water systems. Although municipal water is treated and distributed in accordance with U.S. Environmental Protection Agency (EPA) regulations and is safe for its intended use, microorganisms can enter plumbing systems, attach to the inside surfaces of pipes and equipment to form a biofilm and grow to much greater numbers. Potentially pathogenic microorganisms can then be released into the environment as infectious particles that can pose a threat to human health.
Applying HACCP principles to building water systems enables water systems professionals to prevent contamination from pathogenic microorganisms and other chemical and physical hazards by providing a framework for identifying potential hazards and specifying measures for control that ensure the safety of a building’s water supply.
“The application of HACCP to building water safety is invaluable for protecting the overall health, safety and well-being of the public. Such programs have proven effective for controlling the growth and dispersal of harmful pathogens and this training program will equip water systems professionals with the knowledge they need to apply these principles to their own building water systems,” said Clif McLellan, Vice President of NSF International’s Water Division.
Although HACCP principles are best known for their successful use in food safety applications, they have also emerged as a solution to water safety issues. HACCP-based water safety programs developed by the World Health Organization have proved effective for preventing waterborne disease associated with building water systems.1 In 2010, a HACCP water management program was developed and implemented at the Mayo Clinic in Rochester, MN, yielding significant improvements in building water system safety (Krageschmidt, et. al., 2013).2
The NSF HACCP for Building Water Systems training courses will be taught by William F. McCoy, Ph.D. and Aaron A. Rosenblatt, water systems experts with more than 69 years of combined industry experience:
- William F. McCoy, Ph.D., is Co-Founder and Chief Technology officer of Phigenics LLC, a solutions provider for problems associated with building water systems. Bill has published more than 100 scientific articles and 8 book chapters on topics involving water systems and technologies, including a book entitled “Preventing Legionellosis,” which was published by the International Water Association. He has also developed 29 U.S. patents for new analytical diagnostics and technologies widely used for cooling tower treatment, received the International Water Association Medal for Outstanding Contribution to Management and Science (Berlin 2001), Inventor of the Year Award from the Intellectual Property Law Association (USA 2001), Grand Prize Technical Innovation Trophy from the SUEZ Group (Brussels 2000), Governor’s Pollution Prevention Award from the State of Illinois (USA 1999), and the R&D 100 Award from Research and Development Magazine (USA 1998).
- Aaron A. Rosenblatt is a Principal of Gordon & Rosenblatt, LLC, an independent consulting firm specializing in oxy-halogen chemistry and chemical disinfection with an emphasis on public drinking water supplies and microbial risk management in building water systems. Mr. Rosenblatt is the inventor of more than 20 U.S. patents and author of a number of scientific and technical papers, primarily on drinking water disinfectants, disinfection chemistry and related EPA regulations under the Safe Drinking Water Act. Mr. Rosenblatt has served on the Board of the International Ozone Association-Pan American Group (IOA-PAG), as a member of the American Water Works Association (AWWA) Disinfection and Disinfectants Committees and the Microbial and Disinfection By-Product (M/DBP) Technical Advisory Workgroup during regulatory negotiations for U.S. EPA M/DBP Rule II.
Companies seeking more information about the HACCP training program can contact email@example.com or visit NSF’s water programs webpage. You can also email firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, and email@example.com (China) for additional information.
Editor’s note: To schedule an interview with an NSF International Water Expert, contact Kelly Ingerly firstname.lastname@example.org or +1 734-827-6850.
About NSF International: NSF International is a global independent organization that writes standards, and tests and certifies products for the water, food, health sciences and consumer goods industries to minimize adverse health effects and protect the environment (nsf.org). Founded in 1944, NSF is committed to protecting human health and safety worldwide. Operating in more than 150 countries, NSF is accredited by the American National Standards Institute (ANSI) and is a Pan American Health Organization/World Health Organization Collaborating Center on Food Safety, Water Quality and Indoor Environment.
NSF led the development of the American National Standards for all materials and products that treat or come in contact with drinking water. In 1990, the U.S. EPA replaced its own drinking water product advisory program with these NSF standards. Today, all major plumbing codes require certification to NSF standards for pipes and plumbing components in commercial and residential buildings. NSF International is accredited by the American National Standards Institute (ANSI).
Additional NSF services include management systems registration through NSF-ISR; sustainability standards development, claims and product verification through NSF Sustainability; food safety and quality programs through the NSF Global Food Safety Division; and testing and certification programs for bottled water and beverages, dietary supplements and consumer product industries.