Water Leak Detection in Commercial Buildings

Using the latest technology avoids significant costs and harm to people and property
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Sponsored by WATTS Water Technologies, Inc.
By Peter J. Arsenault, FAIA, NCARB, LEED AP
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The damage caused by water leaks is not only to the building or its contents, but also to the people who occupy the building. In certain situations, water leaks cause mold to grow inside the building, which can directly impact human health. This human health concern can multiply the cost of insurance claims dramatically and, in many cases, may not be covered.

Ignoring the issue of water damage from leaks can become a significant problem for building owners and a serious risk management issue for design professionals, too. At the very least, business or other operations may be disrupted in parts or all of the building. People who occupy a building with undetected water leaks may see their health and general welfare suffer. From a sustainability standpoint, ongoing water leaks are clearly counter to green building and sustainability practices that focus on water conservation and managed use. If an undetected leak goes on for any significant amount of time, then the longer it takes to discover and repair that leak, the bigger the clean-up and the higher the costs will all likely be.

Some examples of typical water leaks affecting people and buildings include the following:

  • A corroded pipe on a hot water tank relief valve went undetected in an office for an entire weekend. The damage extended to nine floors and resulted in losses of $600,000.
  • During a high-rise renovation, an abandoned water line ended up slowly leaking for an extended amount of time. Unbeknownst to the contractor, pressure began building up in the pipe, causing the water column to rise as high as four levels before finally breaking through the plaster. Losses mounted to more than $500,000.
  • A window inadvertently left open in a vacated tenant space caused a pipe to freeze just inside the exterior wall. Coupled with the heat shut off during the vacancy, the pipe burst, and water leaked down four floors. This oversight resulted in a $100,000 loss.

Clearly, water leakage in buildings is an issue that cannot be ignored.

Photo courtesy of WATTS Water Technologies

Cable sensors are sometimes used for large areas or for hard to reach locations, but they can be much more expensive than wireless systems since they require electrical power to multiple locations.


If a water leak occurs in a building, then someone needs to know about it quickly so it can be repaired. Simple visual or auditory observation by users or maintenance staff in commercial buildings is the most basic, but obviously the most unreliable, method. That is because leaks can happen even when the building isn’t occupied or when maintenance staff are off duty. Even if the building is occupied, people may not be near the location where the leak occurs (mechanical rooms, etc.). If the leak is seen, then some people may not recognize it as a problem, assuming that it is a normal maintenance or cleaning activity.

Stand Alone Water Sensors

A better method over simple observation is to have a device available that triggers an audible alarm if a leak occurs, much like a smoke alarm alerts people to that hazard. Water alarms, sometimes called “screamers,” are inexpensive point sensors that are placed on the floor – if they detect water, then they sound an alarm or “scream.” This is technology from the 1980s that are stand-alone devices – i.e., they are not connected either to each other or to any other monitoring system. They are obviously only effective if someone is within earshot to hear it, understands what it is for, and can act on it. Hence, these qualities make them suitable for single family residential use, but not as well suited for commercial use.

Sensing Cables

A more common commercial building solution is to use a long-line sensing cable that can sense water at any point along the wire or an attached sensor. This approach requires electrical power to each wire or sensor, so that needs to be planned and designed for accordingly. While the cables can cover a large area, if there is limited power, then additional electrical wiring is needed which can be costly. Therefore, they are most commonly used in computer server rooms and data centers where lots of power and wiring are already available and there is a need for extensive water leak detection. Sensing cables can also be good for placement in tight, hard to reach areas, although once installed, they may be difficult to maintain and access.

Flow Metering

Another choice to detect a potential leak uses a sensor on supply water piping to monitor the flow in the amount of supply water. The sensor is tracking for any unexpected increase in the amount of water flowing over time through the piping – a possible sign of a leak in the line somewhere. The goal is to sense water that is coming out of the pipe, not just flowing through the pipe. However, since it is only measuring water flow in a piping system, it does not locate where the leak is occurring. There are two types of flow sensing, also called flow metering. The first type is wrapped around an existing meter and is noninvasive, keeping the existing plumbing intact. The second type is installed as a submeter and interrupts the pipe for the meter installation.

In terms of effectiveness, detecting leaks in a commercial building is very difficult to do with flow metering technology alone. In many cases, there may only be a slow drip that needs to be found which wouldn’t be detected by most meters. In a typical 1.5-inch -diameter pipe, for example, the flow meter needs to be extremely sensitive to discern between 10 gallons per minute (gpm) and a potentially damaging 10.05 gpm.

Based on the above, flow metering makes the most sense for small areas where identifying a few sources of water flow is straightforward. It may also be helpful for buildings that do not have 24-hour security personnel to respond to a leak notification when accompanied by a main valve to shut off the water if an alarm occurs. In single-family homes, sensing flow is a good solution since there are only a few water sources, such as where people are showering or cooking. But for commercial buildings, water can be flowing all the time through risers, domestic water lines, wastewater lines, HVAC water lines, etc. Hence, it’s very difficult to use flow meter sensing reliably in so many places, with so much water flow and so much variability.


Given the limitations of the traditional leak detection systems, the most up-to-date option in commercial buildings is the use of a wireless, sensor-based system. Wireless systems can be installed and operate anywhere that a wired system can, just for less cost since there is no wiring needed. They can also be installed in many places where wired systems are not practical. These systems use cloud based IoT (Internet of Things) technology often combined with Radio Frequency (RF) network systems in the building. Just like a smoke or fire detection system, these wireless systems act automatically to sense for water leaks. An internet cloud platform is available that provides remote monitoring anywhere in a building 24/7 and informs building staff when and where leaks are occurring before they become a flood. If needed, electronically controlled shut-off valves can also be added to the design to shut off water flow automatically. Valves can be programmed to close upon the alarm from one or many sensors in a given area or floor.

Photo courtesy of WATTS Water Technologies

A fully coordinated wireless leak detection system uses a tightly managed system to detect and communicate water leak alarms and alerts.

Some of the specific attributes of wireless leak detection systems are discussed in the following sections.


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Originally published in Architectural Record
Originally published in September 2022