EPA's 2011 Drinking Water Infrastructure
Environmental Protection Needs Survey and Assessment
Agency
Summary In 2011, the U.S. Environmental Protection Agency (EPA) conducted its fifth Drinking Water Infrastructure
Needs Survey and Assessment (DWINSA or Assessment). The purpose of the Assessment is to document the 20-year
capital investment needs of public water systems that are eligible to receive Drinking Water State Revolving Fund
(DWSRF) monies — approximately 52,000 community water systems and 21,400 not-for-profit noncommunity water
systems. As directed by the Safe Drinking Water Act (SDWA), EPA conducts the Assessment every four years and uses the
results of the survey to allocate DWSRF funds to the states. The results are also used, in part, to allocate DWSRF tribal
set-aside funds to EPA Regions.
How Was the Assessment Conducted? The approach for the Assessment was developed by EPA in consultation with a
workgroup consisting of representatives from EPA Regions, each state, and the Navajo Nation. The Assessment approach
relied primarily on a random sample survey. A survey questionnaire was used to collect documented needs and costs. In
all, approximately 3,150 public water systems received the survey questionnaire.
EPA mailed questionnaires to all 606 of the nation's large water systems (serving more than 100,000 persons) and 2,234
medium systems (serving between 3,301 and 100,000 persons) in the state survey. Approximately 99 percent of the large
systems and 97 percent of the medium systems returned the questionnaire. The needs of small water systems (serving
fewer than 3,300 persons) in the state survey are based on findings of the 2007 DWINSA and the not-for-profit
noncommunity systems are based on findings of the 1999 efforts; both needs are adjusted to 2011 dollars.
The infrastructure investment needs of water systems serving
Tribal communities were estimated using a statistically-
designed survey. This was the first data collection of these
systems since 1999. The sample included 220 American Indian
and 86 Alaska Native Village water systems. The participant
response rate was 99 and 98 percent, respectively.
What Is the Total Need? The survey estimated a total national
infrastructure need of $384.2 billion for the 20-year period
from January 2011 through December 2030. American Indian
and Alaska Native Village systems represent $3-3 billion of the
total national need. It is important to note that the scope of
the survey is limited to those needs eligible to receive DWSRF
assistance — thus excluding capital projects related primarily to
dams, raw water reservoirs, future growth, and fire protection.
How Does the 2011 Need Compare to the Other
Assessments? The total national need of $384.2 billion
reported by this Assessment is similar to the estimate of $379-7
billion in the 2007 Assessment and $375-9 billion in 2003
(all adjusted to 2011 dollars). The Agency believes the 2011
Assessment continues the success of the 2003 and 2007
efforts in better capturing previously under-reported needs
for rehabilitation and replacement of existing infrastructure as
compared to the 1995 and 1999 Assessments.
SEPA
Total National 20-Year Need
(in billions of January 2011 dollars)
System Size and Type
Need
Large Community Water Systems*
(servingover 100,000 persons)
$145.1
Medium Community Water Systems*
(serving3,301-100,000 persons)
$161.8
Small Community Water Systems
(serving3,300 and fewer persons)1
$64.5
Not-for-Profit Noncommunity Water Systems*
$4.6
Total State Need
$376.0
Alaska Native Village Water Systems
$0.6
American Indian Water Systems
$2.7
Costs Associated with Proposed and Recently
Promulgated Regulations
$4.9
Total National Need
$384.2
Note: Numbers may not total due to rounding.
*	"Large" and "Medium" community water systems are defined
the same as for the 2007 Assessment but are different than
in the 2003 and previous Assessments. See Appendix A in the
DWINSA report for more information
+ Based on 2007 Assessment findings adjusted to 2011 inventory
and cost models.
*	Based on 1999 Assessment findings adjusted to 2011 dollars.

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Total 20-Year Need by Project Type
(in billions of January 2011 dollars)
Treatment
$72.5
^ Source
mmm $20.5
® Other
64.4%	11%
Storage
$39.5
and Distribution
$247.5
The large magnitude of the national need reflects the
challenges confronting water systems as they deal with an
infrastructure network that has aged considerably since
these systems were constructed, in many cases, 50 to 100
years ago.
Total National Need by Project Type With $247-5
billion in needs over the next 20 years, transmission and
distribution projects represent the largest category of
need. This result is consistent with the fact that
transmission and distribution mains account for most of
the nation's water infrastructure. The other categories, in
descending order of need are: treatment, storage, source,
and a miscellaneous category of needs called "other."
Total National Need
$384.2 Billion
Transmission
Note: Numbers may not total due to rounding.
How Does the Need Vary by System Size? The results of the state survey show that the nation's medium-sized
community water systems (serving between 3,301 and 100,000 people) account for the greatest share, 43 percent or
$161.8 billion, of the total national state system need. Large and small systems also have substantial needs of $145.1
billion and $64.5 billion, respectively.
The majority of the American Indian and Alaska Native Village water systems are small, with only 4 medium-sized Alaska
Native Village systems and 73 medium-sized American Indian systems. There are no large American Indian or Alaska
Native Village systems. As a result, the findings of the tribal survey are not reported by system size.
What is the Regulatory Need? Although all of the infrastructure projects in the survey promote the public health
objectives of the SDWA, only $42.0 billion, or approximately 11 percent of the total national need is directly attributable
to compliance with specific SDWA regulations. The majority of projects are needed to ensure the continued provision of
safe drinking water.
Of the total $42.0 billion need for obtaining and maintaining compliance, $37.1 billion is needed for existing
regulations. The remaining $4.9 billion is for compliance with proposed and recently promulgated regulations. Sixty-five
percent of the total regulatory need is associated with microbial contaminants.
How Credible are the Findings? In order to produce an estimate of need nationally and for states receiving an
allocation greater than the base amount of 1 percent of the DWSRF, EPA set a statistical confidence level of 95 percent
with a precision target of ±10 percent. To meet this target, all large systems were surveyed and an adequate number of
medium systems were randomly selected in each fully surveyed state. A national sample of small systems was selected for
the 2007 survey and those findings were used for the 2011 Assessment. For the American Indian and Alaska Native
Village surveys, EPA set the same confidence and precision targets. To meet the targets, all American Indian and Alaska
Native Village systems serving a population of over 3,301 were surveyed, and a random sample of small systems was
selected.
In planning for the 2011 Assessment, EPA, states, and representatives of American Indian and Alaska Native Village
systems reached a consensus on consistent policies regarding replacement and rehabilitation assumptions and
documentation requirements to support projects allowable for the survey. EPA's quality assurance reviews included
significant efforts to ensure policies were followed by all states, American Indian, and Alaska Native Village water systems.
Where Can I Obtain More Information? Information on the Drinking Water Infrastructure Needs Survey and
Assessment Fifth Report to Congress is available in electronic format on the Office of Ground Water and Drinking Water
home page at http: //water, epa. gov/infrastructure/drinkingwater/dwns/index, cfm.
Office of Water (4606M)
EPA 816-F-13-001
April 2013

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