Over the centuries, plumbing has been a “dumb” technology in that it has little to no monitoring that measures any perimeter: usage, duration of usage, flow rates, temperatures, pressures, etc. This continues to be a detriment to design as we rely on such things as Hunter’s Curve and other dated references in today’s designs.

Current water and energy conservation efforts require the profession to better understand the actual dynamics of the installed systems. If data is available, the plumbing engineering community can better right-size the installed systems without oversizing or, worse yet, sizing a system that does not meet the needs of the owner/user.

Most people do not think much about water. It is a liquid necessary to sustain life. It is generally clear, has little taste and can be found in many locations: wells, lakes, rivers, ponds, creeks, rain, etc. Additionally, in most instances, it is not particularly expensive. 

However, the reality is that water can also be harmful as it has the potential to support pathogenic growth. Water is also known as the universal solvent in its pure form, H₂O (two hydrogen to one oxygen atom making up the water molecule).

Groundwater (wells) and surface water (lakes, ponds, etc.) may contain contaminants such as minerals, iron, bacteria, toxic chemicals (aka pollutants), viruses and fecal matter. Even rainwater, which is condensed H₂O, contains contaminants as it falls from the sky and passes through the atmosphere (cleansing the air) and picks up additional contaminants from the surfaces upon which the rain droplets land and run off as stormwater.

Potable water (drinking water) is potentially contaminated water treated to remove harmful pollutants to levels that meet federal and state standards, making it acceptable for consumption.

Why is water quality important?

As plumbing engineers, water quality must be considered in relation to the piping, equipment and occupants of the facility. Water quality includes turbidity, pH, total organic compounds, hardness level, suspended solids, the quantity and type of disinfectant used, and more. 

Why is this important to the plumbing design professional? The quality of the water the facility receives from the source (public or private) affects the piping distribution system, equipment and fixtures within the plumbing design. 

For example, it is estimated that for every 17.1 g/m² (ppm) (1 grain per gallon), water hardness (the amount of dissolved calcium and magnesium in the water) reduces the efficiency of a water heater by 4%. 

Temperature and changes in water quality can adversely affect the residual primary municipal disinfectants within the system, as the incoming water has the potential to contain nutrients that bacteria and biofilm use as food sources. The total suspended solids and particles contained within the incoming building water supply allow Legionella to latch on as growth locations to imbed in the developing biofilm.

The need to right-size the water distribution system has become critical over the years as the plumbing engineering profession comes to grips with the reality of the hidden pathogens most likely contained within the systems, with Legionella being the concern of the moment. 

Plumbing engineers have come to understand the factors that contribute to and play a role in the increased risks — reduced water flow, outdated sizing criteria (Hunter’s Curve), reduced hot water temperatures (energy codes, scald prevention), deteriorating municipal infrastructure — and the need to develop better design, building and infrastructure maintenance/renovation practices.

Minimizing waterborne pathogen risks

The American Society of Plumbing Engineers (ASPE) and the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) have developed guidelines, standards and technical practices to address and minimize the risks associated with the degradation of potable water delivery systems — those hidden systems that everyone takes for granted. 

ASHRAE Guideline 12 addresses four contributing factors to the growth of pathogens within the water piping systems: water temperature, water quality, water age and residual disinfectant. ASPE is in the process of publishing a design guideline to address “engineering methodologies to reduce the risk of Legionella in premise plumbing systems.” 

ASHRAE has further advanced the effort by providing ANSI/ASHRAE 188-2018, Water Management Plan — a document to assist building owners and operators in managing the risk regarding the prevention and control of legionellosis associated with the building water systems. The Centers for Disease Control and Prevention also has produced a Water Management Plan Toolkit to outline minimum requirements of water management plans and buildings where they should be implemented. 

These documents assist and require building owners/operators to fully understand the water systems within their facilities. They need to have knowledge of the system layouts, and what the system serves, including:

What is the source of water that the facility receives? 

How is cold water distributed? 

How is cold water heated to create hot water? 

How is hot water distributed? 

How is all the water collected and delivered to the waste system? 

Owners/operators must implement control measures and best management practices to monitor the installed systems. These plans establish control limits (i.e., temperature levels, disinfectant levels, flow rates, etc.) to ensure that the system meets those limits and to take corrective action should the conditions be outside of the established limits. The process shall be continuous, not a one-and-done approach. As with anything that has potential legal implications, documentation and recordkeeping are critical.

Better documentation through automation

Introducing automation into the plumbing systems through standalone packaged equipment, intelligent equipment controls with remote communication capabilities and integration into the building automation system (BAS) will greatly improve the owner’s/operator’s ability to document the results of the building’s water management plan. 

Generally, the BAS has been used for many years within HVAC mechanical systems, but it is time to consider integrating plumbing systems and equipment into it. This will allow for increased and better oversight of the installed systems, both plumbing and HVAC.

Collecting this information will better document the implementation of the water plan and allow for automatic collection and reporting. Yes, there will be an associated cost to adding data points for entering plumbing data into the BAS. However, such cost can be justified when one considers the expense associated with litigation and legal settlements that have been reported in Legionella cases. 

An additional benefit, if the owners/operators are willing to anonymously share some of this data, is the ability to use actual collected data to better understand usage. This usage data allows plumbing engineers and the plumbing industry to develop more accurate methodologies for right-sizing systems during the design process. 

Automation and mitigating water leaks

Other supplemental benefits of automated plumbing systems include monitoring for leak mitigation. The EPA’s WaterSense program estimates that leaks can account for, on average, 6% of a facility’s total water usage. Most members of the public do not realize or understand the costs associated with leaks and water waste. They see water delivered by the fixture and some of it going down the drainage system. 

What they do not see being lost from the system is the volume of treated water leaking into the ground or environment. These losses include not only the water product but also the costs of treatment to make the water potable, the energy costs associated with moving the water from treatment to delivery, and the costs resulting from the damage caused by such leaks.

It is not apathy but a lack of knowledge and information regarding plumbing/piping systems that contributes to these costs and waste of treated water. The collection and sharing of this data from BAS-monitored systems can assist decision-makers in understanding the impact that uncontrolled water use is having on their businesses. 

When most property owners only see a water bill every month or two, it is almost impossible for them to gather enough information to make informed decisions. This water loss also adds to the cost associated with the sanitary sewer, as the sewer is typically based on the volume of water entering the facility. For example, a building using 1 million gallons per month could save approximately $50,000 a year on water fees with a 6% reduction in water use.

Mitigating water damage risk using smart plumbing systems could reduce costs associated with water leakage. Based on claim data from 2014 to 2020, approximately 75% of all real estate industry property losses are due to accidental discharge of water from plumbing, HVAC systems and appliances. 

Water damage causes billions of dollars in financial losses across the real estate industry, with claims that can become extremely costly for businesses. Only a small percentage of building owners and managers are prepared for such losses by having a written damage prevention plan.

Other supplemental benefits of automated plumbing systems are monitoring system operations, alleviating end-user complaints on system performance, allowing owners/operators to be proactive with building issues, mitigating risk, and controlling costs while providing a safe and healthy building for clients and occupants.

Tool development to provide accurate water demand data 

Collection and sharing of this data would also assist the various code authorities as they strive to develop tools to help the design community in right-sizing based on accurate water demand. The International Association of Mechanical and Plumbing Officials developed a Water Demand Calculator for residential applications. It is currently working with several university and industry professions to do the same for commercial applications. 

This is a challenge, given the diversity of facilities and plumbing uses. However, it is certainly a step in the right direction. These and other guidelines, standards and codes aid design professionals in providing better designs for our clients while reducing costs and minimizing the potential for oversizing these critical systems.

With that said, one must remember that the design professional, the engineer of record (EOR), is legally and morally responsible for the designs he or she places their seal and signature upon. The EOR holds the liability to see that the design protects public health, safety and welfare while meeting the client’s desires within the established budget. 

Additionally, the design professional must balance all the guidance provided by the codes, standards, guidelines and regulations (some of which conflict with or contradict one another) to ultimately provide a safe and functional facility.

David D. Dexter, FNSPE, FASPE, CPD, CPI, LEED BD+C, PE, is a registered Professional Engineer, Certified Plumbing Inspector, and Certified Plans Examiner with more than 40 years of experience in the installation and design of plumbing systems. He specializes in plumbing, fire protection and HVAC design, as well as forensics related to mechanical system failures. Dexter serves as chair of ASPE’s Main Design Standards Committee, chair of both ASPE and NSPE-OH Bylaws Committees, and co-chair of the Professional Engineer Working Group.