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 infrastructure 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 defined as the relationships between two or “Communities often ignore the needs 

more of water and wastewater utilities until critical infrastructures. 

they experience a loss of service.” 

Critical Infrastructures are the physical and virtual assets, systems, – Don Broussard, WSCC Chair 

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. Environmental 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 

1

For additional information on critical infrastructure and key resources, 

please visit: www.dhs.gov/files/programs/gc_1189168948944.shtm 
 

 

 

 

 

 

 

Water SeCtor InterDePenDenCIeS 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 compromised 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 Drinking Water Service Disruption 

Consequences 

Potential Wastewater Service Disruption 

Consequences 

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 participating 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 interdependencies 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 contact WSD-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/