Water quality in buildings is defined by a matrix of measurable parameters: disinfectant residual, turbidity, pH, total organic compounds, hardness and suspended solids, among others. Each parameter directly influences the performance and longevity of plumbing systems.
Hard water scale reduces water-heater efficiency and shortens equipment life. Changes in temperature affect the persistence of disinfectant residuals. Suspended solids provide surfaces for Legionella growth, and incoming water can carry nutrients that support biofilm formation.
Poor water quality affects far more than system performance. Public reporting and federal oversight reviews have described cases in which occupants of federal buildings were not informed promptly about water contamination involving lead, copper and Legionella (https://bit.ly/4avgGJP), underscoring the operational and public health risks associated with inadequate monitoring and communication.
A building’s water distribution system can create conditions that support Legionella, which occurs naturally in water sources. When Legionella proliferates and becomes aerosolized — through showers, cooling tower drift or decorative fountains — the risk of Legionnaires’ disease transmission to building occupants becomes real.
According to the Centers for Disease Control and Prevention, Legionnaires’ disease kills more people in the United States than any other reportable waterborne disease; between 3% and 33% of infections are fatal, and worldwide incidence is estimated to be underreported by eightfold to tenfold.
ASHRAE Guideline 12:2023 Managing the Risk of Legionellosis Associated with Building Water Systems identifies four main contributing factors to Legionella growth in plumbing systems: sediment, water temperature, water age and disinfectant residual. Several modern building practices have inadvertently amplified these risks:
Water-conserving fixtures that reduce flow;
Oversized piping using outdated pipe-sizing criteria based on Hunter’s Curve;
Lower hot water temperatures driven by energy codes and scald prevention;
Deteriorating municipal infrastructure.
Regulatory and legal landscape
The regulatory environment surrounding water management is expanding rapidly. Illinois requires Legionella testing policies for hospitals and nursing care facilities (https://bit.ly/4f6mvjz); New York mandates maintenance programs for cooling towers and Legionella management plans for healthcare facilities (https://bit.ly/4eGda0k); Michigan requires water management plans based on the CDC toolkit and ASHRAE 188, including risk assessments and ongoing verification (https://bit.ly/3SDJ6LA).
Proposed legislation in Pennsylvania, Senate Bill 712, 2025-26, and Maryland, Senate Bill 65, 2026, and an earlier proposal in North Carolina, House Bill 971, 2021, would extend similar requirements to additional building owners, generally referencing ASHRAE 188 and, in some cases, validation testing.
Insurance and risk-management guidance is also moving in the same direction. Environmental insurance advisors increasingly frame Legionella exposure as a building owner risk that can involve claims, cleanup costs, remediation expenses and business interruption, and recommend formal water management plans as part of risk mitigation (https://bit.ly/4uX3cOh).
When Legionnaires’ disease claims arise, investigations commonly focus on the source of exposure and whether the owner or operator maintained water systems appropriately. Public-health and legal investigations may review maintenance logs, water-sampling results, system operation, cleaning practices and corrective-action records.
Liability is typically evaluated through a negligence framework: whether the responsible party had a duty to maintain safe premises, breached that duty through inadequate maintenance or controls, and caused exposure and illness (https://bit.ly/4oRB6Te).
Water management program: Current state and limitations
Per ANSI/ASHRAE Standard 188-2021, Legionellosis: Risk Management for Building Water Systems, a water management program (WMP) is the risk management plan for the prevention and control of legionellosis associated with building water systems, including documentation of the plan’s implementation and operation (https://bit.ly/44Bg95D).
ASHRAE 188 and the CDC Water Management Program Toolkit are the two leading standards outlining minimum water management program requirements (https://bit.ly/4eOij6z). A water management program is an operational process that should begin during the building’s construction process and continue through occupation and operation. You cannot simply design a building to meet ASHRAE 188; the plan must be actively maintained throughout the facility’s life.
ASHRAE 188 references ASHRAE Guideline 12 as a design resource for Legionella risk mitigation. Because Guideline 12 is not fully comprehensive for premise plumbing applications, many practitioners also rely on guidance from American Society of Plumbing Engineers texts, including Engineering Methodologies to Reduce the Risk of Legionella in Premise Plumbing Systems.
Implementing and monitoring control measures is central to any water management program. As per the CDC, when a control limit — such as temperature or disinfectant residual — falls outside the acceptable range, the plan must trigger timely corrective action to restore safe operating conditions. These data points also provide valuable insight into water use and system performance, helping the industry better align pipe-sizing criteria with current technologies and system designs.
In practice, this means continuously verifying that control measures remain within established limits and documenting every excursion and response. That cycle of monitoring, verification and correction is the operational backbone of an effective program — but when it relies on manual checks alone, critical changes can go unnoticed between inspections.
Traditional water management programs depend heavily on manual measurement. Technicians check temperatures, record disinfectant levels, and log results on paper or in spreadsheets. While this may satisfy minimum compliance requirements, it leaves major gaps in real-time visibility, response speed and documentation quality. That limitation is driving increased interest in building management system (BMS)-enabled water monitoring.
The building management and controls industry has expanded significantly over the past two decades — but plumbing domestic water distribution systems have remained outside that progress toward intelligence and adaptive buildings.
Where connections between a BMS and plumbing do exist, they are almost entirely confined to the mechanical room: equipment-level monitoring of booster pumps, recirculation pumps, water heaters and leak detection. These connections are valuable, but they represent equipment monitoring rather than system-level visibility into the performance and water quality of the distribution network itself.
For plumbing engineers, that gap matters. The design decisions we make — pipe sizing, recirculation layout, water heater setpoints and dead-leg minimization — directly determine how effectively a water management program can be implemented and maintained, while also providing valuable insight into water quality.
How a BMS transforms water management
Buildings may already have automation systems that can be expanded — or a new BMS can be designed from the outset — with the explicit intent of supporting water management program implementation. The same infrastructure used to monitor HVAC performance can be leveraged for domestic water systems, provided the appropriate sensors are specified, applicable NSF requirements are met as per NSF/ANSI 61: Drinking Water System Components — Health Effects and NSF/ANSI/CAN 372: Drinking Water System Components – Lead Content, and integration is designed in from the start.
This may be a straightforward extension of an existing BMS or a dedicated platform for domestic water management. Cost-effective strategies are also available for installing sensors and monitoring equipment in existing buildings.
The simplest starting point is temperature sensing at specific locations across the domestic hot and cold water systems. Hot water supply and return temperatures below 124 F create conditions favorable to Legionella growth. Continuous monitoring at the water heater outlet, at the end of each recirculation branch, and at representative fixtures gives the BMS the data needed to detect when the system is drifting out of safe operating range before a problem develops — a significant improvement over spot-checking during scheduled walk-throughs.
Pressure and flow monitoring extend that picture further. By tracking pressure differentials and flow rates across distribution zones, operators gain visibility into stagnation in low-demand branches, developing blockages and whether recirculation flow rates are meeting design intent. Stagnation is one of the primary contributors to Legionella amplification; flow-based monitoring enables the BMS to flag branches not seeing adequate circulation and trigger corrective action before conditions deteriorate.
Inline water quality meters provide continuous feedback on conductivity, free and total chlorine levels and pH — parameters directly relevant to Legionella risk and to the performance of chemical disinfection programs. These sensors carry a higher installed cost than temperature or pressure sensors but provide data that cannot be captured any other way on a continuous basis.
For buildings with cooling towers, supplemental disinfection systems, or complex recirculation networks, integrated water quality monitoring is a meaningful step toward the system-level intelligence that water management programs require but rarely receive.
Taken together, temperature, pressure, flow and water quality sensors give the BMS the inputs needed for a real-time, system-level view of domestic water performance. Maintaining data quality over the life of the system is essential because operators rely on that information to make decisions that affect health and safety.
BMS platforms can also help identify developing issues before they become failures and provide possible corrective-action steps. Similar fault detection and diagnostics capabilities are already becoming code-required for HVAC systems in buildings meeting the requirements defined in IECC 2024, and incorporating domestic water systems into that design approach can provide measurable benefits.
Rather than functioning as a static document that identifies risk points, the water management program can be supported by dynamic BMS data showing whether each control point is currently within its defined safe range. Historical trends can also show how system conditions change over time, making the water management program a living operational tool rather than a paper filing exercise.
When control limits are exceeded, alerts can be sent immediately to maintenance staff, enabling corrective action in alignment with ASHRAE 188 and CDC water management program objectives. Automated reports covering temperature logs, disinfectant residuals, flow rates, alarms and corrective actions create a defensible compliance record for regulators, investigators and insurers.
Beyond monitoring and alerting, a well-integrated BMS can automate operational responses currently performed manually — or not at all. Automatic flushing of identified dead legs, triggered on a time schedule, ensures that low-use branches are purged regularly. This directly addresses one of the most difficult operational challenges in large buildings: ensuring every branch sees regular flow, not just the high-use ones near mechanical rooms and occupied floors.
Additional operational benefits
Automated water management delivers value beyond Legionella risk mitigation. The Environmental Protection Agency’s WaterSense program estimates that leaks account for more than 6% of a facility’s total water use (https://bit.ly/4waNoZk). Flow meters that identify unusual consumption combined with immediate alerting help contain these losses.
For example, a building that uses 1 million gallons (about 3,785,410 L) per month would save 720,000 gallons annually — a 6% reduction (about the volume of an olympic-size swimming pool).
Water damage prevention is equally compelling. Industry claim analyses have found that a significant share of commercial real-estate water damage losses are tied to accidental discharge from plumbing, HVAC systems and appliances (https://bit.ly/3SrXbfd). Leak-detection sensors and automatic shutoff valves integrated with the BMS reduce both the frequency and severity of these events.
Water management programs are becoming regulatory requirements in more states and increasingly important risk-management tools for building owners, insurers and facility operators. Traditional manual monitoring still leaves critical gaps in response time and documentation.
Automated water management — through strategic sensor placement, real-time monitoring, automated reporting, fault detection and diagnostics, and historical trending — closes those gaps and shifts operations from reactive to proactive.
For plumbing engineers, the direction of best practice is clear: design water systems with continuous monitoring in mind, specify the sensing infrastructure that supports it, and position the buildings we engineer for the operational resilience that regulators, insurers and building owners increasingly expect.
Automated water management is no longer only an emerging option — it is rapidly becoming a standard component of safer, more resilient buildings.
Maria Grazia Campos, DCES, LEED AP, is an associate principal at Callan Consulting Engineers, with over 16 years of experience in controls and building management systems. She is an active member of ASHRAE and the American Society of Plumbing Engineers. Maria’s systems engineering background has allowed her to holistically evaluate the impacts between all building systems and their integration and value-add capabilities for all facility types.
James Dipping, PE, CPD, GPD, ARCSA AP, FASPE, is a nationally recognized plumbing engineer and thought leader with over 29 years of experience. As Senior Principal, Plumbing Engineering Discipline Lead - North America at Stantec, he has advanced plumbing design standards across Stantec’s Buildings practice. An ASPE Fellow, James has played a pivotal role in shaping industry best practices, particularly in water safety and sustainability.
