The building construction industry, driven by building owners, operators and tenants, are pushing the envelope when it comes to high performing and safe buildings. The desire for flexibility, connectivity, comfort, health, energy conservation and safety are top requests for a multitude of building types.

The move to more intelligent buildings is one approach to achieving these goals. Commonly, energy efficiency in building design is immediately associated with an HVAC system and the overall building envelope. And while they certainly are major factors, providing an intelligent domestic water system can have an impact on many of those areas as well.

Waterborne Pathogens Hiding in Plain Sight

According to the Centers for Disease Control and Prevention (CDC), 7.2 million Americans get sick every year from diseases spread through water (http://bit.ly/3WO4rz1). The number of people falling ill with Legionnaires’ Disease, the most common waterborne illness in the United States, has grown by nearly 900% since 2000 (https://bit.ly/3u2qaa7).

Legionella is a general category of bacterium all-too-commonly found in our water supplies. And the king of the species, Legionella pneumophila, is responsible for approximately 90% of all infections. Approximately 10% of people diagnosed with Legionnaires’ Disease will die due to complications from their illness. For those who get Legionnaires’ Disease during a stay in a health-care facility, the mortality rate climbs to about 25%.

Building owners and operators have good reason to be so concerned about Legionella as plumbing domestic water systems are the predominant source of the bacteria. If Legionella grows in a plumbing system, the bacteria can spread to humans via small droplets or vapor inhaled into the lungs. Common sources where these droplets are “made” include:

• Showerheads and sink faucets
• Hot tubs
• Hot water tanks and heaters
• Decorative fountains and water features
• Large, complex plumbing systems
• Cooling towers

But how does the bacterium get a foothold in water systems? It’s unfortunate that there is no one-stop shop to prevent Legionella development. The major considerations for engineers to mitigate risk in domestic water systems are water temperature, disinfectant residual, incoming water quality and stagnation. Complex plumbing systems add additional challenges, as do ambient conditions, building location and building/piping age.

Legionella bacteria have an ideal temperature range for growth, which happens to be in line with temperatures that humans find desirable for handwashing, bathing, and showering. Thus, operating building in such a way to keep the domestic water system outside of the ideal growth temperatures is recommended. However, this is not as simple as elevating operating temperatures. Considerations are going to vary based on building use, occupancy and fixtures used.

ASHRAE offers a guide, “Legionellosis: Risk Management for Building Water Systems,” (http://bit.ly/39Pq9jc) which it describes as “essential for anyone involved in design, construction, installation, commissioning, operation, maintenance, and service of centralized building water systems and components.” Likewise, the CDC offers its “Toolkit: Developing a Water Management Program to Reduce Legionella Growth and Spread in Buildings” (https://bit.ly/3OnY3dH).

Pipe Size and Water Stagnation

Before rushing out to install a bunch of low-flow fixtures to save water, be advised that doing so in haste could be putting building occupants at risk. Today’s water pipe-sizing practices are outdated and don’t consider the decreased volumes of water used by widespread low-flow fixtures. These devices can leave water in the pipe and increase building water age. 

Stagnant water in these systems can create an environment ideal for cultivating dangerous pathogens, including the bacterium responsible for Legionnaires’ Disease.

When water flows at higher volumes through the plumbing systems, primary and secondary disinfectants provided by the municipality have a better chance at controlling waterborne pathogens because the chemicals used are limited in their effective life span. The use of low-flow fixtures in conjunction with outdated water pipe-sizing practices allow the disinfectants to expire before the water reaches your faucet. As a result, pathogens are given the opportunity to grow and multiply inside the building pipes.

The good news is that the industry is making some progress in this issue. Research is in the works, and some building specific tools are now developed to help with right-sizing a building domestic water piping system. At the forefront is the Water Demand Calculator (www.iapmo.org/water-demand-calculator). At this time, this tool is recognized for only certain building types in the Uniform Plumbing Code (UPC). 

That said, it is a much-needed starting point to reduce overall building water piping volumes and recognizing that fixtures are flowing lower than they were in the 1940s. There is no denying that water conservation is important, but it must be paired with a properly sized piping system. Water conservation efforts cannot supersede keeping buildings.

Keep Out of Legal Hot Water

Treating water with high temperatures seems like a good answer to controlling the growth of pathogens such as Legionella, but that approach could cause other problems. In the hospitality industry, the two biggest complaints are the lack of hot water and water that’s too hot or scalding. 

With an inability to confirm the water temperature in the supply piping to a guest room at the time such a complaint is lodged, hospitality establishments are forced to go along with whatever the guest claims, even when the complaint leads to a lawsuit. 

If building management systems began incorporating more water monitoring, it would be possible to know exactly what the water temperature is in each pipe at any given time. Not only would this data enable buildings to confirm or dismiss water complaints, but it would ultimately give facilities the tools to improve systems performance and occupant health.

With an accurate picture of water temperatures as measured by sensors strategically placed throughout the building’s piping system, these levels can be properly adjusted to improve system performance, better reduce water pathogen growth and improve overall water quality. With this key building intelligence in hand, building engineers and managers would be much better equipped to take a proactive water management role and deliver safer, more hygienic water at the right temperature. 

The failure to monitor the temperature of domestic water systems outside the mechanical room can increase a building’s exposure to risk, litigation and hurting the bottom line.

A Call for Water Intelligence

The same level of technologies and controls currently in place in our building’s HVAC systems must be applied to plumbing systems as well. Right now, most connectivity from the plumbing systems to the building automation system takes place in a mechanical room. But this simply is not enough to provide the intelligence required to effectively improve water quality and occupant safety for years to come. 

The more monitoring points you have, the more you know about your building. Conversely, the more monitoring points you have, the more costly this endeavor becomes.

Every building is different, but the objective is the same: know the temperatures at the far points of your distribution system where water is drawn by building occupants. The following examples illustrate large and medium-impact classifications and the immediate effect on end-users. Health-care buildings will likely expand on these, while buildings such as warehouses will not.

1. Large impact:

• Before the first and after the last fixture in vertical cold and hot water risers.
• At the start and end of cold and hot water main runs in a horizontal application (corridor, building wing, etc.).
• At junction points in hot water supply and return system piping (to assist in balancing efforts).
• At the end of branches to large fixture groups.
• Before the first and after the last fixture in fixture groups in high-risk areas such as those used by the public.
• At the fixture level with intelligent plumbing fixtures.

2. Medium impact:

On the outlet side of pressure-reducing stations, specifically those serving pressure zones in high-rise applications.

• At water service entry to the building.
• At the end of branches to fixture groups of two or fewer.

Installing monitors at specific points outside of the mechanical room only gets you so far. Digitizing this information allows for immediate awareness of system performance and allows this data to be logged and stored for record-keeping purposes. The protection to your bottom line is twofold: your occupants are safer, and you have stronger evidence to counter any negligence lawsuit brought against you.

With digitization, you can have minute-by-minute data instead of month-to-month or year-to-year data. Automated monitoring systems also eliminate the need for dedicated maintenance hours to manually take temperatures at plumbing fixtures throughout the building. This data can be used in the event of a Legionella lawsuit or can be used to document temperatures if a scalding or thermal shock incident is cited.

We live in a world where data is knowledge — and knowledge is king! Having data available can go a long way in operating a successful water management plan, protecting your building occupants and protecting your pocketbook. 

James Dipping, PE, CPD, ARCSA AP, GPD, LEED AP BD+C, is the technical director of plumbing engineering for ESD, a global engineering firm. He has more than 25 years of experience in the plumbing design and construction industries. Dipping is a licensed Professional Engineer, has spoken at American Society of Plumbing Engineers Tech Symposiums, and has published several articles in many industry magazines.