Saving America's Watershed

What we don’t see we don’t think about. The United States has an estimated 1.2 million miles of

underground sanitary and combined sewer systems just beneath our feet. Our population continues to grow

pushing the current infrastructure systems to their limits. With these growing pressures on the aging

infrastructure systems they are failing and can’t handle the increased demand.

Today a simple rain event can threaten our clean water by causing sanitary sewer overflows (SSO) and

combined sewer overflows (CSO). The SSO’s and CSO’s are caused by unmaintained and underdeveloped

underground infrastructure. During wet events water enters the sewer system via infiltration and inflow (I/I)

as a result the systems exceeds capacity and the overflow occurs.

In a 2004 report to Congress the EPA estimated that 850 billion gallons of untreated wastewater and storm

water are released as CSO’s every year. Each year 23,000 to 75,000 SSO’s occur resulting in 3 billion to

10 billion gallons of untreated waste water being released. The sewage release is a direct threat to America’s

watershed and raises public health concerns. The EPA also reports “Microbial pathogens and toxics can be

present in CSOs and SSOs at levels that pose risks to human health. Human health impacts occur when

people become ill due to contact with water or ingestion of water or shellfish that have been contaminated by

CSO or SSO discharges.

Many stoppages in gravity systems are caused by a buildup of debris which can include grease, sand,

sludge or other types of materials. Root intrusion and other structural defects such as pipe joint

offsets, cracks and protruding taps can also cause slow flows resulting in debris build-up in mains

and private lateral connections. Once the blockage has begun it traps more and more debris which

will cause a back-up and if not discovered in time a sewer overflow

A vital part of stopping these SSOs and CSOs are Sewer System Maintenance and Inspection Programs.

It is recommended that 100 % of a sewer system be hydro flushed on a 3 to 5 year cycle. Included in this

time frame problematic pipelines should be visually inspected with robotic cameras which can identify

additional unforeseen problems.


The success that the nation has achieved in improving water quality since passage of the Clean Water Act is

due to the collective efforts of federal and state agencies, municipalities, industry, non-governmental

organizations, and citizens. Continued cooperation among these groups is essential to meet the challenges

to clean water that lie ahead. As described in this Report to Congress, numerous pollutant sources threaten

the environment and human health, but establishing direct cause-and effect relationships is often difficult.

The information necessary to manage water quality problems comes from many sources. EPA recognizes the

value of working with stakeholders and has pursued a strategy of extensive stakeholder participation in its

policymaking on CSO and SSO issues. Likewise, as communities continue to implement CSO and SSO

controls, further cooperation with municipal, industry, and environmental organizations is essential to

ensure successful development and implementation of environmental programs. - 2004 EPA Report to

Congress on the Impacts and Control of CSOs and SSOs

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