Pipe breaks in a water distribution system are one of three critical metrics that can be used to measure the degree of ... Pipe leakage is a way to assess the system's overall condition. ⢠Different pipes have different risk characteristics ... 2 | Asset Management ⢠Breaks & Leaks. Although water utilities typically take actions to ...
Fact Sheet
ASSET MANAGEMENT Breaks & Leaks
What Pipe Breaks & Leaks Reveal About Pipe Health Quick Facts • Pipe breaks are a key criterion in pipe replacement • Large diameter pipe breaks result, on average, in a cost to utilities of more than $1 million each • Total cost of small diameter pipe breaks is about $10,000 each • Pipe leakage is a way to assess the system’s overall condition • Different pipes have different risk characteristics Overview When deciding which pipes to replace, many water
flows (40%), condition or type of materials (30%), and need for pipe size changes (30%) (Kirmeyer et al. 1994).
utilities consider pipe breaks as an important factor. According to one study, 75% of water utilities cited pipe
According to the same survey, the average pipe break rate
breaks as a key criterion in pipe replacement decisions.
for a water utility was between 0.21 to 0.27 breaks per
Other common factors noted were pipe age (45%), low
mile of pipeline per year (Kirmeyer et al. 1994). Another study cited an average of 0.25 breaks per mile per year (Grigg 2007).
Why Replace? Pipe Breaks 75%
Pipe Age 45%
Material Low Type/ Pipe Size Flows Condition Changes 40% 30% 30%
Pipe breaks in a water distribution system are one of three critical metrics that can be used to measure the degree of optimization in the system. The other two metrics are chlorine residual (measuring water quality integrity) and pressure management (measuring hydraulic integrity). Breaks reflect the physical condition of the
Figure 1. Criteria for pipe replacement
distribution system (Friedman et al. 2010).
waterrf.org
Small Diameter Pipe Breaks
Total costs (of large pipe breaks) according to one recent study ranged from $6,000 to $8.5 million, with an average cost of $1.7 million.
Small diameter pipes are the most common type of pipe in a water system and, because they are of weaker construction that large diameter pipes, have more frequent breaks. Water utilities can manage small diameter pipe breaks by measuring the frequency of the break rates. This approach is acceptable given that small diameter pipe breaks are typically not catastrophic and the costs to repair or replace the pipes are generally relatively low.
Although water utilities typically take actions to manage Small diameter pipes often are located in residential or
and reduce pipe breaks through monitoring, preventing all pipe failures is impossible. Water utilities usually
semiresidential areas. When breaks occur, the pipe can
manage pipes and their failures using two distinct cat-
usually be repaired while the system is in operation, caus-
egories: large diameter pipe breaks and small diameter
ing minimal or no impact to customers. If an area must
pipe breaks.
be shut down to allow for a pipe repair, the affected area is often more limited than that associated with a large diameter pipe break.
Large Diameter Pipe Breaks When large diameter pipe breaks occur, the conse-
The total cost of a typical small diameter pipe break for
quences are significant (e.g., flooding, major disruptions
a water utility is estimated at $10,000, based on limited
of service, city or neighborhood boil-water orders). What
analyses. These total costs consist of $5,000 in direct
constitutes a “large” pipe will vary from utility to utility,
costs to a utility and $5,000 in indirect costs to society
but typically a pipe in the 12-inch and larger to 24-inch
(e.g., traffic delays or traffic rerouting caused by a break)
and larger diameter range will be considered a large and
(Grigg 2007).
critical pipe by most utilities. As such, water utilities work The report, Non-Destructive Condition Assessment for
very hard to eliminate these types of breaks.
Small Diameter Cast and Ductile Iron Pipe, identified One example of a large diameter pipe break occurred
failure mechanisms and modes in small diameter cast
with the Massachusetts Water Resources Authority in
iron pipe and ductile iron pipe and their associated
2010. A coupling ring on a large diameter pipe failed,
direct and indirect failure costs as shown in Figure 2.
resulting in approximately two million people being placed on a boil- water order (Stratus
$30,000,000
Consulting 2011). $25,000,000
Though large diameter pipe breaks occur less frequently than small diameter pipe breaks, they are more expensive to repair. Total costs, according to one recent study, ranged from $6,000 to $8.5 million, with an average cost of
$20,000,000 ≤6" (150mm) $15,000,000
>6" (150mm) ≤12" (300mm)
$1.7 million. Direct costs to water utilities varied from $6,000 to almost $7.5 million. The largest
$10,000,000
>12" (300mm) ≤16" (400mm)
portion of these costs (52%) was associated with claims paid directly by the utility and/or the utility’s insurance company for property damage (Gaewski and Blaha 2007).
$5,000,000
$0
Direct cost of failure
Indirect cost of failure
Annual CA expenditure
Source: Rolfe-Dickinson et al. 2014
Figure 2. Direct and indirect failure costs by diameter at 29 utilities
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Asset Management
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Breaks & Leaks
References
The figure clearly shows that the majority of failure costs are incurred by pipelines # 6", with the total direct cost
AWWA (American Water Works Association). 2009.
of failure for the 29 participating utilities exceeding
M36 Water Audits and Loss Control Programs. 3rd ed.
$27.5 million USD annually (Rolfe-Dickinson et al. 2014).
Denver, Colo.: AWWA. http://www.awwa.org/store/ productdetail.aspx?productid=51439782
Leakage Management and Detection
———. 2014. “AWWA Free Water Audit Software (Version 5.0).” http://www.awwa.org/home/awwa-news-details/
Water utilities can use pipe leakage as a way to help
articleid/2641/awwa-free-water-audit-software-
evaluate the condition of the water system, given that
version-5-0-now-available.aspx
more leakage is often associated with a reduced physical condition of the system. Leaks can occur from pipe damage caused by third parties, corrosion, or a few areas of stress in the pipes, as well as from joints in the distribution system.
Fanner, P. 2006. Evaluating Water Loss and Planning Loss Reduction Strategies. Project #2811. Denver, Colo.: AwwaRF. Fanner, P., R. Sturm, J. Thornton, R. Liemberger, S. E. Davis, and T. Hoogerwerf. 2007. Leakage Management Technologies. Project #2928. Denver, Colo.: AwwaRF.
There are two ways in which water utilities can assess leakage. One way is through conducting a system-wide
Friedman, M., G. Kirmeyer, J. Lemieux, M. LeChevallier, S. Seidl, and J. Routt. 2010. Criteria for Optimized
water audit, which estimates water consumption and
Distribution Systems. Project #4109. Denver, Colo.:
water loss. The process enables water utilities to develop
Water Research Foundation.
performance indicators to assess water loss, benchmark themselves with other water utilities, and set performance metrics (Fanner 2006; Fanner et al. 2007;
Gaewski, P.E., and F. J. Blaha. 2007. Analysis of Total Cost of Large Diameter Pipe Failures. Denver, Colo.: AwwaRF.
AWWA 2009, 2014).
Grigg, N. S. 2007. Main Break Prediction, Prevention, and
Another way in which water utilities can assess leakage is
Hughes, D. M., Y. Kleiner, B. Rajani, and J. Sink. 2011.
Control. Project #461. Denver, Colo.: AwwaRF. through conducting leakage investigations on all or part
Continuous System Acoustic Monitoring: From Start to
of the water system, using dedicated technologies to find
Repair. Project #3183. Denver, Colo.: Water Research
the leaks. Many of these technologies can track the sound of a leak, allowing the utility to identify the exact point of the leakage and make repairs (Hughes et al. 2011).
Foundation. Kirmeyer, G. J, W. Richards, C. D. Smith. 1994. An Assessment of Water Distribution Systems and Associated Research Needs. Project #706. Denver,
Pipe Cohorts A pipe cohort is a group of pipes with similar characteris-
Colo.: AwwaRF and American Water Works Association. Rolfe-Dickinson, S., A. Davies-Jordan, G. Cleveland, P.
tics. This concept is helpful in pipe management, because
Halai, and G. Lehman. 2014. Non-Destructive Condition
defining different pipe cohorts can be helpful in identify-
Assessment for Small Diameter Cast & Ductile Iron
ing pipes that have different risk characteristics.
Pipe. Project #4230. Denver, Colo.: Water Research Foundation and Sydney Water.
Changes in pipe manufacturing, such as the introduction
Stratus Consulting. 2011. Multi-Agency Response to a
of new pipe-making technologies, are a major criterion
Major Water Pipe Break: A Massachusetts Case Study
when identifying pipe cohort concerns (e.g., longevity of
and Evaluation, Final Report. Project #4411. Denver,
a pipe and risk of breakage). For instance, pit cast gray
Colo.: Water Research Foundation, the Association of
iron pipe and centrifugally cast gray iron pipe of the same
Metropolitan Water Agencies, and WaterISAC.
diameter should likely be considered in different pipe cohorts, because the significant differences in manufacturing cause the pipes to behave differently. Other factors that can affect pipe longevity and breakage include transportation and installation methods.
Last updated August 2016
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