As water demands grow, management of public water supplies, such as San Francisco's Hetch Hetchy water system, will take on even greater importance. (Photo: iStockphoto)
With water supply becoming an increasingly important environmental and economic issue, a new report delivers a timely message: Residential sprinklers can be easily integrated with local water systems.
NFPA Journal®, November/December 2009
By James Lyons
Of the big-picture environmental issues emerging in this new century, few are as urgent as the topic of water supply. Globally, according to water.org, nearly a billion people, or one in eight, lack access to clean water. In the U.S., a growing population, one that is shifting steadily south and west, is putting increased strain on local water supply sources, as are growing demands from industry and agriculture. Compounding the problem is the potential effect of climate change; widespread drought conditions have further depleted water supplies across the country.
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James Lyons answers questions about the "Integration of Residential Sprinklers with Water Supply Systems" report.
What does the report cover?
How was the research for the report conducted?
What challenges did the targetted communities experience?
How is the report intended to be used?
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COAST TO COAST
The 20 communities surveyed for the Newport Partners report have ordinances requiring sprinklers in all new homes.
View the complete report.
- Aberdeen, Maryland
- Annapolis, Maryland
- Avondale, Arizona
- Celina, Texas
- Clarendon Hills, Illinois
- Cottonwood, Arizona
- Galt, California
- Glenwood, Illinois
- Libertyville, Illinois
- Monterey, California
- Montpelier, Vermont
- Northbrook, Illinois
- Northstar Community, California
- Ojai, California
- Paradise Valley, Arizona
- Piperton, Tennessee
- Redmond, Washington
- University Park, Texas
- Westminster, Maryland
So when a community is considering residential fire sprinklers, it’s understandable if people are a little sensitive when the subject of water supply comes up. Those folks can rest easy, however; a new study finds that residential sprinkler systems can be easily integrated with local water systems in ways that do not affect water quality, and can even help conserve water supply by using less water to suppress home fires when they occur.
Residential fire sprinkler systems are becoming a more common feature in new houses throughout the country. The systems bring an effective life-safety technology into our homes, one that for many years has been commonplace in commercial buildings. The use of fire sprinklers in townhouses and single-family homes has been on the rise, and could increase dramatically in the next few years in new U.S. housing construction. This potential jump in activity is primarily due to passage of local ordinances and laws, as well as changes to model codes—which many states and communities adopt as their own—that now require residential sprinklers in all new one- and two-family dwellings. The 2006 editions of NFPA 101®, Life Safety Code®, and NFPA 5000®, Building Construction and Safety Code®, included mandates for residential sprinklers in all new one- and two-family dwellings. Additionally, the 2009 edition of the International Residential Code (IRC) was revised to make fire sprinklers mandatory in new homes.
The increase in sprinkler use has been accompanied by questions concerning their impact on community water supply systems. Those systems are an integral part of American life, with more than 280 million Americans relying on them for water in their homes. Like any other part of our country’s infrastructure, though, these systems are facing many challenges as they age, and as the communities they serve change over time. The main issues communities currently face in managing their water supplies boil down to water quality and maintaining an adequate water supply. More specifically, do all those sprinklers pose a threat to our water supply?
To get a better understanding of how communities are dealing with these issues, and to learn what kind of impact residential sprinklers actually have on local water supplies, NFPA sponsored a just-completed research study titled "Integration of Residential Sprinklers with Water Supply Systems" (PDF, 842 KB). The study, conducted by Maryland-based Newport Partners, surveyed a mix of building department, fire service, and water provider staff in 20 U.S. communities. Each community already has a residential sprinkler ordinance for all new single-family homes that took effect subsequent to 1999, so they have recent experience implementing home fire sprinklers on a wide scale for the first time. The survey questions were based on a literature review of the topic, and covered items such as whether it’s required to meter the water flow to the sprinkler system, the magnitude of any cost impacts from larger meters or tapping fees, and inspection requirements for backflow prevention devices.
The survey is especially timely considering NFPA’s nationwide advocacy of residential sprinklers, and also considering the arguments employed by sprinkler opponents. When a major new system is introduced to homebuilding, after all, it can cause a significant ripple effect. These ripples often come in the form of how to integrate the new building system, which impacts builders, contractors, local building departments, designers, and manufacturers. In the case of home fire sprinklers, a major area of concern has been the integration of sprinklers with the public water supply. This integration concerns builders, fueled in part by horror stories of water utilities requiring them to use larger water meters, which builders say can add to the cost of constructing a home. It also concerns the fire service, which needs to know that sprinklers will be adequately designed so they work when they need to. And it concerns local water suppliers, who need to figure out how these systems should connect to their supply network in a way that avoids adverse effects on their system and operations.
Based on the survey/interview results, the communities studied have developed practical solutions for sprinkler integration with the water supply system. While sprinklers are still a fairly recent development for these communities, water supply integration requirements have been put into place, and there are no examples of insurmountable problems or issues. In fact, neither design problems nor significant added costs have resulted from water supply integration issues in most communities. Water suppliers, building departments, and fire services have developed workable approaches to accommodate residential sprinklers, creating safer communities while maintaining the local water supply.
For design issues such as whether or not to meter fire sprinkler flow, communities have successfully adopted different approaches. The decisions are sometimes based on technical factors. For example, in communities where water flow to the sprinklers is not metered, it was often stated that they did not want a water meter to restrict flow to the sprinklers or otherwise complicate the design. In other cases, design decisions are based on staying consistent with nearby jurisdictions, so communities end up adopting the same provisions. In fact, communities in the same state generally adopt fairly uniform requirements on items like metering the flow to sprinklers, which makes the ordinance more predictable for stakeholders. More unusual design requirements, such as dual water service lines or dual water meters, are rare and are typically driven by local issues that would not apply in most other areas.
Homes with sprinklers may sometimes have a larger-sized connection, or tap, into the municipal supply line, larger or additional water meters, or higher monthly service fees when compared to the same house without sprinklers. A larger tap or additional water meters can mean higher fees to builders; in one community a one-inch water meter costs $3,500, while a five-eighths-inch meter costs $3,000. If the use of sprinklers in the home triggers any of these changes, the resulting fees can be attributed to the sprinkler system. Sometimes called the "hidden costs" of sprinklers, such issues are often directly related to a community’s sprinkler design requirements.
In 11 of the 20 communities surveyed, however, no cost impact resulted from sprinkler-induced changes to water meter size, additional water meters, or changes to tap size. Sprinklers also did not result in higher monthly service fees from water suppliers. In some cases, a larger meter might have been required to accommodate the sprinklers, but it did not cost more. In other cases, where the sprinkler system service line splits upstream from the domestic meter, there was no change necessary in the size of the domestic meter. Another common scenario is that the normal tap size and water meter used in most houses, including those without sprinklers, were often adequate to accommodate sprinklers, so no increase in size, or cost, was brought on by the sprinklers.
For the other nine communities where one or more of these factors did add cost, and where the cost could also be calculated based on available data, the average added cost of those factors was about $400. This average includes a $1,400 added cost in one community, where a second service line and a second water tap were required to supply the sprinklers. The rationale for this design requirement was the ability to disable the domestic water supply while still maintaining flow to the sprinklers. This unusual example shows that local requirements for design can indeed have cost impacts and should be weighed carefully by communities deciding on their provisions.
In other cases, sprinkler system designs have adapted to the landscape of fees and regulations already in place. For example, in one community the increase in the water connection fee from one domestic meter size to the next jumped by thousands of dollars. This community also requires that the flow to fire sprinklers be metered, so adding sprinklers could increase the meter size and cost thousands. To avoid this scenario, builders have developed a different sprinkler system connection scheme that does not increase the domestic water meter size (or the connection fee), but instead uses a second water meter to monitor the flow to the sprinklers. The result is that the flow to the sprinklers is metered, satisfying the local requirement, while the domestic water meter size stays the same, producing a major cost savings. This fee structure was not intended to penalize fire sprinklers, since it pre-dates the ordinance, but it has had an impact on system design.
Requiring sprinklers in all new homes also raises a host of new issues related to their operation and upkeep. One concern is whether water suppliers could be held liable if they disable water service to a residence due to failure to pay—thereby disabling the sprinklers in many cases, depending on system design—only to see a fire occur in that residence. While this issue has received some discussion in communities with a sprinkler ordinance, it has generally not been a major concern. This is mainly due to the fact that residential sprinkler systems are primarily a life safety system, and homes without domestic water supply are deemed uninhabitable. One community especially concerned with this issue modified its water service termination letters to mention that the home’s fire sprinkler system will become inactive once water service is terminated.
Another issue is the inspection of backflow devices used in some sprinkler designs. Inspections of backflow devices are required in communities where state law requires such inspections, unless the system design does not involve a backflow prevention device, and where the community’s ordinance requires this type of device. Communities use a range of approaches to overcome the challenges in administering these regular inspections, including penalties for non-compliance, tax-assessment incentives for compliance, and moving toward system designs that avoid the need for backflow prevention devices altogether. As an example of this last approach, one community in the study now requires a combination system configuration to avoid the need for such devices. In a combined system, water supply piping is shared between the domestic supply and fire sprinkler system, so the issue of backflow from sprinkler lines into domestic lines is avoided and backflow prevention devices are unnecessary.
As additional communities and states adopt residential sprinkler ordinances based on model building codes, it will be necessary for them to develop their own approaches for integrating sprinklers with local water supplies. The results of the "Integration of Residential Sprinklers with Water Supply Systems" study indicate that a range of reasonable approaches can work, and that states and communities can exercise a fair amount of flexibility in handling issues of particular concern. Approaches that satisfy the needs of builders, water suppliers, and the fire service are certainly within reach, and communities are encouraged to draw from this research to better understand key issues and form their own particular strategies.
James Lyons, P.E., is a senior engineer in building systems research at Newport Partners, LLC, in Davidsonville, Maryland.