United States
Environmental Protection
Agency
Understanding
Water Sector Interdependencies
Water Sector Infrastructure Interdependencies
Water is essential to life; human health, the economy, and many community services rely on water. Water in-
frastructure damage can adversely affect the operation of all other critical infrastructure sectors. Conversely,
damage to other critical infrastructure sectors could negatively affect drinking water and wastewater services,
thereby creating an infrastructure interdependency. Infrastructure
Interdependencies are denned as the relationships between two or
more critical infrastructures.
"Communities often ignore the needs
of water and wastewater utilities until
they experience a loss of service."
- Don Broussard, WSCC Chair
Critical Infrastructures are the physical and virtual assets, systems,
or networks that are necessary for the functioning of society and the
economy. The water sector, comprised of both drinking water and wastewater utilities, has been designated by
the U.S. Department of Homeland Security (DHS) as one of 18 critical infrastructure and key resource (CIKR)
sectors1. As a CIKR, the protection of the nation's water supply infrastructure is a top priority for the U.S. En-
vironmental Protection Agency (EPA), the designated Sector-Specific Agency (SSA) for the water sector. EPA
continues to work with other federal agencies, state drinking water programs, private sectors, and the public to
increase preparedness and improve community resiliency in the face of water service interruptions.
Water Sector Critical Infrastructure
In the United States, public drinking water and wastewater infrastructure includes approximately:
• 160,000 public drinking water systems (PWSs) that provide drinking water to about 84% of the U.S.
population; 2.3 million miles of drinking water distribution system piping
• 16,000 publicly owned treatment works (POTWs) that provide sewage treatment to approximately
75% of the U.S. population
Demonstrated Interdependencies
with the Water Sector
The following CIKR and/or community
services share interdependencies with the
water sector, and may be negatively affected
in the event that drinking water and/or
wastewater services are not available:
• Emergency services
• Healthcare facilities
• Schools
• Transportation
• Energy Production
• Postal and shipping services
• Telecommunications
• Food and beverage production and
preparation
1For additional information on critical infrastructure and key resources,
please visit: www.dhs.gov/files/programs/gc_1189168948944.shtm
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WATER SECTOR INTERDEPENDENCES Page 2
Potential Consequences of Drinking Water and Wastewater Service Disruptions
Natural disasters and accidents can disrupt drinking water and wastewater services. The Northeast Blackout
of 2003 resulted in widespread drinking water and wastewater treatment system failures and the discharge of
sewage into beach areas, lakes, streams, and other water systems. In 2005, Hurricane Katrina disabled or com-
promised the operation of more than 1,220 drinking water systems and 200 wastewater treatment facilities.
These two events, amongst many others, demonstrate the broad consequences of water service disruptions;
several specific consequences are described in the table below:
Potential Drinkii
Consequence-
Potential Wast
Consequenci
Lack of water for consumption, cooking, bathing,
flushing, fire suppression, etc.
Sewage or storm water discharges (causing damage
to buildings, institutions, and landmarks)
Loss of water for commercial irrigation, food supply,
production of consumer needs
Release of hazardous chemicals into wastewater,
negatively affecting public health and the environment
Decreased public confidence in water supply
Need to pre-treat wastewater before enters
wastewater treatment plant; need to properly dispose
of wastewater residual
Need to access alternate water supplies and/or issue
a public notice to boil water
Lack of wastewater services, posing public health and
sanitation issues
Adverse economic effects as industry and local
governments experience water service interruption
Sewage or storm water discharges (causing damage
plants, animals, and aquatic life)
Loss of water for cooling (disabling electrical and
telecommunications equipment)
Adverse economic impacts, loss of property, and
damaged service provider reputation
Collaboration with Interdependent Infrastructures
A number of actions to enhance the relationship between the water sector and other critical infrastructures and
to strengthen water sector preparedness and community resiliency:
• Identify critical services and businesses that rely on water and coordinate planning and exercises to prepare for
emergencies
• Identify potential steps for reducing risks in the event of water service disruptions
• Identify and incorporate best practices for water service disruptions into emergency response plans (ERPs)
and continuity of operations plans (COOPs)
• Take advantage of existing mutual aid and assistance programs [e.g., Water/Wastewater Agency Response
Networks (WARNs)]
• Engage decision makers in water sector and critical infrastructure preparedness planning process by partici-
pating in Local Emergency Planning Committees (LEPCs)
EPA's Community-Based Water Resiliency Initiative provides communities with the tools necessary for
launching a water resiliency program. This initiative was implemented to increase the awareness of interdepen-
dencies with the water sector and provide a holistic approach to water preparedness and community resiliency.
CONTACT US For more information on the water sector interdependencies and the CBWR initiative,
please contactWSD-Outreach@epa.gov or visit us at http://water.epa.gov/infrastructure/watersecurity.
Office of Water (4608-T) | EPA 817-F-10-008 | August 2010 | http://water.epa.gov/
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