The Modern Hot Water System Approach to Keep Higher Education Buildings Safe and Operational

• By Brian Armstrong
• 05/15/25

Higher education campuses face unique structural and operational demands. With a range of old and new buildings, a variety of facility types, and ambitious sustainability goals, it's essential that no aspect of infrastructural performance is overlooked.  Facility managers must be equipped to provide a safe, reliable and efficient space for students, faculty and guests.

Water systems are a critical component. The complex arrangements that provide housing, administrative and academic facilities with safe, hot water are often a challenge for institutions looking to keep their buildings running properly. With safety protocols, water quality and decarbonization opportunities at stake, it's crucial for facilities teams to consider reliable measures.

While every campus has its own unique framework, a beneficial first step is to develop a Water Safety Management Plan (WMP) that focuses on core design and operational principles. Often developed in collaboration with an industry specialist, a WMP acts as an essential resource for plumbing system designers and facility managers. It clearly defines system goals, temperature strategies, and infection control protocols to help with healthy hot water objectives.

Higher educational facilities focused on becoming safer, greener, and more cost effective must consider the four key pillars of a calculated WMP: infection control, scald protection, compliance, and sustainability. Let’s look at how each of these pillars supports a campus' hot water system.

Infection Control

Waterborne pathogens like Legionella can pose a serious risk in all hot water systems if allowed to incubate and spread. While young and healthy college students are not considered to be as susceptible to serious infection as the elderly or immune compromised, a  proactive risk management strategy for a higher educational facility hot water system is still advised. Given the wide variation in water systems, water quality and environmental conditions across the U.S., there is no one-size-fits-all method for infection control. As a result, Legionella risk management specialists often use the term “barrier” to describe the strategies they implement to reduce the risk of Legionella growth and transmission.

The first and foremost  barrier (and the easiest one to implement) is effective water temperature control. As a general rule, water heaters should operate at 140°F (60°C) or above, and system water temperatures should remain above 122°F (50°C) at all times. Meanwhile, stagnant sections of pipe, including long distances to low-use fixtures, can allow water temperatures to drop into the ideal range for Legionella growth, between 95°F (35°C) and 115°F (46°C). This creates a heightened risk to users. To prevent this, it is important to implement smart piping layouts, use appropriate fittings and schedule periodic fixture flushing to manage the “water’s age.”

Today’s water temperature control technologies support an infection control strategy with digital recirculation valves now offering precise temperature management—delivering water within 2°F (1°C) of the set point. Models with a 1°F (1°C) inlet-to-outlet temperature differential are particularly effective in low temperature loss systems designed to maintain the ASHRAE 188 Guideline 12-recommended minimum without raising mixing valve set point temperatures to potentially harmful levels.

Scald Protection

If the first pillar of a healthy hot water system is an infection control regime that calls for hot water generation at 140°F (60°C) or higher, then the second pillar must be a methodology that optimizes protection against scald risk for users. Fortunately, today’s digital mixing valves (DMVs) maintain a high degree of accuracy, resist temperature creep, and communicate with building automation systems, elevating user safety. These valves obey system set points within 2°F (1°C) and can issue alerts or default to cold/return water only, as needed. Temperature creep, which is caused when a system idles without fixture demand, occurs if the mixing valve fails to correctly balance return water and reheating needs. High-performance digital mixing valves prevent this by using multiple built-in thermistors, including one that reads return water temperature to control temperature creep.

Occasionally, hot water systems in educational facilities are designed with recirculation system temperatures of 140°F (60°C) or above. In these situations, the need for effective scald protection at the point of use becomes elevated.

One potential solution to evaluate is the use of thermostatic shower valves and under-sink thermostatic mixing valves (TMVs). While the internal thermostats in these fixtures offer thermal shutoff in the event of inlet failure, the maximum temperature limiting feature, or “hot stop” feature, offers the most consistent protection. However, hot stops often require seasonal adjustment and must be reset after servicing. In contrast, a digital mixing valve recirculating the water at 123°F–125°F (51°C–52°C) enables simpler, safer and less complex point-of-use solutions.

In addition, point-of-use TMVs often have narrow waterway and include rubber seals that may promote pathogen growth. If a thermal disinfection regime needs to be implemented, point-of-use controls would need to be manually overridden, adding complexity to the process and increasing the maintenance load.

If the prevailing safety feature of the thermostatic shower valve is its hot stop, a pressure balance shower valve (PBV) not only offers the same feature, but it also adjusts for pressure fluctuations in the inlet supplies. A PBV can maintain consistent water temperature even if the pressure in one of the supplies changes. If there is a complete loss of pressure in one of the supplies—either hot or cold—the PBV will shut off the water flow entirely to prevent sudden temperature changes, protecting the user from scalding or thermal shock. With a digital mixing valve providing a stable hot water supply and a correctly set “hot stop,” the user can then fine-tune the final shower temperature to suit.

The risk of scalding at bathroom or dormitory sinks is generally low, as most users can quickly remove their hands. However, special consideration should be given to individuals with physical limitations. A straightforward and reliable solution is a basic mechanical valve, preset to a safe outlet temperature before the faucet. Ideally, this valve should feature an integral hot stop set to 110°F (43°C) and be supplied by a recirculating hot water system delivering water at 122°F–125°F (50°C–52°C), regulated by a digital mixing valve.

Compliance

Another important reason for an institution to implement a WMP is to ensure the hot water system remains compliant. A well-developed WMP defines key elements such as user safety protocols, water heating and temperature control strategies, and the system’s overall operating framework. To ensure the WMP is both effective and appropriate, it should be guided by industry-recognized Standards of Care, which encompass relevant laws, standards, and best practices that support system safety and performance.

These include documents such as the OSHA Technical Manual, Joint Commission Environment of Care, ASHRAE Guideline 12-2020, ASHRAE Standard 188-2021, and VA Directive 1061. Each provides clear recommendations for setting and monitoring hot water system temperature limits—critical for preventing the growth of waterborne pathogens such as Legionella.

Certifications developed by The International Association of Plumbing and Mechanical Officials (IAPMO) and the American Society of Sanitary Engineering (ASSE) also outline industry standards that support best practices for safe and effective plumbing system design, installation, and maintenance. All components used in a hot water system should be certified to comply with applicable IAPMO–ASSE standards. For water heating, this includes ASSE 1082 and 1084; for water temperature control, key standards are ASSE 1070, 1016, and 1017. Digital mixing valves, in particular, should comply with the 2022 ASSE/IAPMO IGC 384-2022 standard, which reflects the elevated performance expectations for digital technologies in recirculating hot water systems.

Sustainability

As institutions increasingly prioritize sustainability, the shift away from fossil-fuel-based systems toward electric alternatives—such as heat pumps—is becoming more widespread. A popular substitute heavily promoted in related applications is air source heat pumps that use CO2. While CO2 is a suitable refrigerant for domestic single-pass water heating, CO2 heat pumps are suboptimal for recirculating hot water systems and will require the integration of multiple storage tanks, including swing tanks. Swing tanks often sustain water at temperatures that compromise standards for waterborne pathogen management, including ASHRAE 188 Guideline 12.

Whether drawing from geothermal sources, cooling chillers, exhaust fans, boiler stacks, or even sewage, high-temperature water-source heat pumps are a smart solution for higher education facilities with access to geothermal infrastructure or another form of recoverable waste heat.

Beyond electrification, there are additional opportunities to optimize a hot water system’s energy efficiency. For example, Pacific Gas & Electric recently completed a study in California. In a simulated 44-unit apartment, they delivered a 10–18% energy savings when using point-of-source water temperature control (via a central master mixing valve) instead of point-of-use controls—savings of which came largely from reduced heat loss at higher recirculation temperatures, with some contribution from tank stratification. These lab results were further validated when digital mixing valves were installed in field tests across five sites, including a hotel and medical complex, similar to that of a traditional college dormitory. As a result of the study, proposal to include central master mixing valves within commercial and institutional buildings in California is currently matriculating  through the plumbing code update process.

Condensing water heaters aren’t new, but recent advancements have made them much more efficient than earlier models. While the ultimate goal is to phase out fossil fuels, North America's abundant supply of relatively clean and affordable natural gas remains a practical option—producing nearly $1 worth of hot water for every $1 of fuel. A hybrid system that uses a water-source heat pump for the primary load and supplements with a condensing gas or steam/water heater as needed offers a practical next step in the evolution of heating solutions. Nanobubble technology also improves both system health and efficiency by removing scale, reducing pipe thermal resistance, and lowering the energy required to heat or cool water. The removal of scale also significantly reduces required maintenance, product failures and their associated costs. 

Keeping Higher Education Buildings Safe and Operational

As the needs of academic facilities grow more complex, maintaining a reliable and efficient hot water system has never been more important. A well-executed WMP—grounded in the core pillars of infection control, scald protection, compliance, and sustainability—provides a framework for safe operations and long-term resilience. More than just a plumbing concern, healthy hot water impacts student well-being, energy performance, and the overall adaptability of campus infrastructure. With the right plan in place, facility teams can stay ahead of risk, meet critical standards, and support a more sustainable future for higher education.