America’s Children and the Environment Environments and Contaminants Drinking Water

Environments and Contaminants: Drinking Water

Methods

Indicator

E7. Estimated percentage of children ages 0 to 17 years served by community water systems that
did not meet all applicable health-based drinking water standards, 1993-2019.

E8. Estimated percentage of children ages 0 to 17 years served by community water systems
with violations of drinking water monitoring and reporting requirements, 1993-2019.

Summary

EPA's Safe Drinking Water Information System Federal Version (SDWIS/FED) includes
information on populations served and violations of maximum contaminant levels or required
treatment techniques by the nation's 160,000 public water systems. For each calendar year,
SDWIS/FED violation data for the nation's 50,000 community water systems were obtained
from EPA Office of Water, listing all violations that occurred during all or part of that year. For
Indicator E7, health-based violations were grouped into different types based on the violation
code and chemical contaminant code.

For Indicator E8, violations of monitoring and reporting requirements were grouped into
different types based on the violation code. For each state and type of violation, the fraction of
the population served by violating systems was estimated as the total population served by
community water systems with one or more violations divided by the total population served by
all community water systems. For each state and type of violation, the number of children served
by violating systems was estimated as the fraction of the population served by violating systems
multiplied by the total population of children ages 0 to 17 years in the state. Indicators E7 and
E8 are the percentages of children served by violating systems in relation to all children served
by community water systems, estimated by summing the numbers of children served by violating
systems across all states and dividing this total by the national total population of children ages 0
to 17 years.

Drinking Water Standards Violation Data

Drinking water standards violation data from the EPA Safe Drinking Water Information System
Federal Version (SDWIS/FED) were obtained directly from EPA's Office of Water1. The file
was extracted from SDWIS/FED in March, 2021. This file contains the public water system

' Chandler Klawitter. 202-564-1954

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identification code (PWSID), violation code, contaminant code, state (primary state served by
the water system), population served, violation begin date, violation end date, return to
compliance date, compliance status code, and compliance status description. This file has one
row for each violation excluding inapplicable violations with code 500. This file only contains
violations by Community Water Systems. The population served is the current (fourth quarter
2019) estimate of the population served by that water system. Violations by systems not assigned
to one of the 50 U.S. States or Washington DC were excluded. Therefore, we did not include
violations in Puerto Rico and other U.S. territories -. We also excluded violations on tribal lands
which are assigned to the EPA regions. Finally, we excluded a single SWTR TT for PWSID
CA1910067 determined to be invalid by EPA staff.

Each violation was assigned an effective end date based on the compliance status description,
violation end date, and return to compliance date, as follows:

•	Compliance status description = "Known." Return to compliance date is missing.
Effective end date = violation end date.

•	Compliance status description = "Inactive" Return to compliance date is the date the
system became inactive. If the return to compliance date is before the violation begin
date, then exclude that violation. Otherwise effective end date = earliest of violation end
date and return to compliance date.

•	Compliance status description = "Returned to compliance." Effective end date = earliest
of violation end date and return to compliance date.

•	Compliance status description = "Open." Return to compliance date and violation end
date are both missing. Effective end date = 31 December, 2019.

Each violation was assigned to each and every calendar year that intersects the period from the
violation begin date to the effective end date. Thus the violation is assigned to each calendar year
such that the violation begin date is on or before December 31 and the effective end date is on or
after January 1.

For Indicator E7, health-based violations were grouped into the following violation types using
the violation and contaminant codes:

•	All health-based: Violation codes 41, 42, 45, and 48 with contaminant code 700 (Ground
water rule), 40 (Filter backwash recycling rule), or any of the following violations

o Lead and copper: Violation codes 57, 58, 59, 63, 64, 65

o Total coliforms: Violation codes 1 and 2 with contaminant code 3000 (Coliform
pre-TCR) only. Total Coliform Rule: Violation codes 21 and 22 with all
contaminant codes. Revised Total Coliforms Rule (April 2016): Violation codes
1 A, 2A, 2B, 2C and 2D with contaminant code 8000 only*
o Chemical and radionuclide: Violation codes 1, 2 and 7 with all applicable

contaminant codes**
o Surface water treatment: Violation codes 33, 37, 41-45, and 47 with all
contaminant codes except 700

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o Nitrate/nitrite: Violation codes 1 and 2 with contaminant codes 1038, 1040, and
1041 only

o Disinfectants and disinfection byproducts: Violation codes 11, 12, 13, and 46 with
all contaminant codes. Violation code 2 with contaminant codes 1009, 1011,
2456, and 2950 only

* In 2016, the Total Coliform Rule was replaced by the Revised Total Coliform Rule which
began implementation in April 2016.

** The applicable contaminant codes for Chemical and radionuclide are as follows:

Volatile organic chemicals: 2265, 2257, 2378, 2380, 2955, 2964, 2968, 2969, 2976, 2977, 2979,
2980, 2981, 2982, 2983, 2984, 2985, 2987, 2989, 2990, 2991, 2992, 2996
Synthetic organic contaminants: 2005, 2010, 2015, 2020, 2031, 2032, 2033, 2034, 2035, 2036,
2037, 2039, 2040, 2041, 2042, 2046, 2050, 2051, 2063, 2065, 2067, 2105, 2110, 2274, 2306,
2326, 2383, 2931, 2946, 2959

Inorganic chemicals: 1005, 1010, 1015, 1020, 1024, 1035, 1036, 1045, 1074, 1075, 1085, 1094
Radiological contaminants: 4000, 4006, 4010, 4100, 4101, 4102, 4174, 4264

For Indicator E8, monitoring and reporting violations were grouped into the following violation
types using the violation codes:

• Any violation: Violation codes 19, 34 with all contaminant codes and 31 with

contaminant code 700 (Ground water rule), 39 (Filter backwash recycling rule), or any of
the following violations

o Lead and copper: Violation codes 51, 52, 53, 56, and 66

o Total coliforms: Total Coliform Rule: Violation codes 23, 24, 25, and 26. Revised
Total Coliforms Rule (April 2016): Violation codes 3A, 3B, 3C, 3D, 4A, 4B, 4C,
4D, 4E and 4F with contaminant code 8000 only***
o Chemical and radionuclide: Violation codes 3 and 4

o Surface water treatment: Violation codes 29, 32, 36 and 38 with all contaminant

codes. Violation code 31 with contaminant codes 200 and 800 only
o Disinfectants and disinfection byproducts: Violation codes 27, 30, and 35

*** In 2016, the Total Coliform Rule was replaced by the Revised Total Coliform Rule which
began implementation in April 2016.

In a calendar year, a PWSID may have one or more violations of a given violation type. Only the
first such violation is selected. For each violation type, state, and calendar year, the total
population served by all violating PWSIDs was calculated by summing across the PWSIDs,
counting each violating PWSID once only.

For each state, the total population served by community water systems was obtained from the
SDWIS/FED inventory files. EPA-Office of Water staff provided this summary file. The data for
2019, fourth quarter, frozen as of January 2020, were used for these analyses. Only the 50 U.S.
States or Washington DC, identified by their postal code abbreviations, were included.	

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Census Data

We obtained children's populations by state for each year from 1993-2019.

For 1993-1999, the source was U.S. Census Bureau files:

"Estimates of the Population of Counties by Age and Sex: 1990-1999," August
30, 2000. The file headers are "(CO-99-9) Population Estimates for Counties by
Age and Sex: Annual Time Series July 1, 1990 to July 1, 1999." The file headers
were "(CO-99-9) Population Estimates for Counties by Age and Sex: Annual
Time Series July 1, 1990 to July 1, 1999."

http://www.census.gov/popest/data/counties/asrh/1990s/CQ-99-09.html.

These files give county populations by age and sex for 1990- 1999. We summed these
populations by year and state across all counties in the state, for children ages 0 to 17 years , and
both sexes.

For 2000-2009, we used the bridged-race intercensal population files obtained from the CDC
website:

https://www.cdc.gov/nchs/nvss/bridged race.htm as of October 26, 2012, following release
by the U.S. Census Bureau of the revised unbridged intercensal estimates by 5-year age
group on October 9, 2012.

The bridged-race intercensal population files contain estimates of the resident population of the
United States as of July 1 of each year 2000-2009, by county, single-year of age (0, 1,2,..., 85
years and over), bridged-race category (White, Black or African American, American Indian or
Alaska Native, Asian or Pacific Islander), Hispanic origin (not Hispanic or Latino, Hispanic or
Latino), and sex. There is one SAS file for 2000-2004 and another SAS file for 2005-2009. Files
are available in SAS dataset and text formats; we used the SAS dataset format for these analyses.

We extracted the variables: state, county, age, racesex, hisp, and pop2000 to pop2009. The
racesex variable is a single coded value for each combination of race and sex, e.g., racesex = 1
denotes White males. The value popXXXX gives the population as of July 1 of the calendar year
XXXX for a given state, county, age, racesex combination, and ethnicity. The state children's
populations for each year 2000-2009 were obtained by summing the variable popXXXX over all
counties in a state, for children ages 0 to 17 years , all values of "racesex" and all values of
"hisp."

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For 2010-2019, we used the bridged race Vintage 2019 postcensal population files obtained from
the CDC website:

National Center for Health Statistics. Vintage 2018 postcensal estimates of the resident
population of the United States (April 1, 2010, July 1, 2010-July 1, 2019), by year, county,
single-year of age (0, 1,2,85 years and over), bridged race, Hispanic origin, and sex.
Prepared under a collaborative arrangement with the U.S. Census Bureau. Available from
https://www.cdc.gov/nchs/nvss/bridged race.htm as of July 9, 2020, following release by the
U.S. Census Bureau of the unbridged Vintage 2019 postcensal estimates by 5-year age group
on June 25, 2020.

The bridged race 2010 to 2019 population files contain estimates of the resident population of
the United States as of July 1 of each year2010-2019 (the data for April 1, 2010 were not used
for these analyses) by county, single-year of age (0, 1, 2,..., 85 years and over), bridged-race
category (White, Black or African American, American Indian or Alaska Native, Asian or
Pacific Islander), Hispanic origin (not Hispanic or Latino, Hispanic or Latino), and sex. Files are
available in SAS dataset and text formats; we used the SAS dataset format for these analyses.

We extracted the following variables: state, county, age, racesex, hisp, pop2010 jul, pop2011,
pop2012, pop2013, pop2014, pop2015, pop2016, pop2017, pop2018, and pop2019. The racesex
variable is a single coded value for each combination of race and sex, e.g., racesex = 1 denotes
White males. The value popXXXX or popXXXXjul gives the population as of July 1, XXXX
for a given state, county, age, racesex combination, and ethnicity. The state children's
populations for 2010 -2019 were obtained by summing the variables pop2010 jul, pop2011,
pop2012, pop2013, pop2014, pop2015, pop2016, pop2017, pop2018, and pop2019 over all
counties in a state, for children ages 0 to 17 years , all values of "racesex," and all values of
"hisp."

Calculation of Indicator

Indicators E7 and E8 are calculated as follows.

Using the water quality violation data, the PWSIDs violating a given type of violation during
each calendar year were listed. For each type of violation and calendar year, only the first
violation by a PWSID was selected.

1. For each state, type of violation, and year, the populations served by violating systems were
obtained by summing the populations served across the violating PWSIDs:

Violating population (state, violation type, year) = E Population served

where this sum is taken over all violating community water systems in the state for the given
calendar year.

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2.	The fractions of the populations served by violating systems were obtained by dividing the
violating population in the state for that year by the total population served by all community
water systems in the state. The total populations served by community water systems in each
state were obtained from the SDWIS/FED inventory data:

State population fraction affected (state, violation type, year) =

Violating population (state, violation type, year) /

Total population served (state)

3.	The number of affected children in each state was estimated by multiplying the state
population fraction affected by the state children's population. This estimate assumes an even
geographic distribution over water systems of individuals under the age of 18 in each state for
each year. This estimate also assumes that all children are served by community water systems;
see below for a discussion of this assumption. This estimate also makes no adjustment for
children in one state that are served by water systems that primarily serve another state:

State children affected (state, violation type, year) =

State population fraction affected (state, violation type, year) x
Children 0-17 (state, year)

4.	The national number of children served by violating systems was obtained by summing the
state numbers of children served by violating systems:

National children affected (violation type, year) =

E State children affected (state, violation type, year)

5.	The percentage of children served by violating water systems was obtained by dividing the
national number of children served by violating water systems by the total number of children in
the 50 U.S. states and Washington DC:

Percentage children affected (violation type, year) =

[National children affected (violation type, year) /

E Children 0-17 (state, year)] x 100%

where the sum is across all states.

In Step 3, an assumption is made that all children ages 0 to 17 years are served by community
water systems. In fact, some of the U.S. population, and hence some children ages 0 to 17 years,
are not served by community water systems, so this assumption is unrealistic. To address this
issue, suppose instead that a fraction g of children are served by community water systems,
where g is approximately the same for every state, but could vary by year. In Step 3, the number
of children affected in a given state is given by:

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State children affected (state, violation type, year) =

State population fraction affected (state, violation type, year) x
Children 0-17 (state, year) x g(year),

since there are Children 0-17 (state, year) x g(year) children ages 0 to 17 years that are served by
community water systems in that state and year, Step 4 is unchanged. In Step 5, the percentage of
children served by violating systems in relation to the children served by community water
systems is obtained by dividing the national number of children served by violating water
systems by the total number of children served by community water systems:

Percentage children affected (violation type, year) =

[National children affected (violation type, year) /

E Children 0-17 (state, year) x g(year)] x 100%.

Because the same fraction g(year) appears in both the numerator and denominator, it cancels out.
Therefore, even though not all children are served by community water systems, Indicators E7
and E8 estimate the percentage of children served by violating systems in relation to the children
served by community water systems.

Questions and Comments

Questions regarding these methods, and suggestions to improve the description of the methods,
are welcome. Please use the "Contact Us" link at the bottom of any page in the America's
Children and the Environment website.

Data Files

The following files are needed to calculate this indicator:

~ SDWIS/FED violation data. This file contains the public water system identification code
(PWSID), violation code, contaminant code, contaminant type, state (primary state served
by the water system), population served, violation begin date, violation end date, return to
compliance date, compliance status code, and compliance status description This file has
one row for each violation excluding inapplicable violations with code 500. This file only
contains violations by Community Water Systems (as defined by EPA).11 The population
served is the current (fourth quarter 2019) estimate of the population served by that water
system. This file was obtained directly from EPA staff.

11 Community Water Systems have at least 15 service connections or serve 25 or more of the same population year-
round.

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• SDWIS/FED inventory data. This file contains the total population served by all active
community water systems in each state and year. The data for 2019, fourth quarter,
frozen as of January 2020, were used for these analyses. This file was obtained directly
from EPA staff.

• Census data. This file contains the state FIPS codes, year, and children's population. For
1993-1999, we obtained this information from the U.S. Census Bureau files:

"Estimates of the Population of Counties by Age and Sex: 1990-1999," August
30, 2000. The file headers were "(CO-99-9) Population Estimates for Counties by
Age and Sex: Annual Time Series July 1, 1990 to July 1, 1999."
http://www.census.gov/popest/data/counties/asrh/1990s/CQ-99-09.html.

These files give county populations by age and sex for 1990 to 1999. We summed
these populations by year and state across all ages 0 to 17 years and both sexes.

For 2000-2009, we obtained this information from the bridged-race intercensal
population files:

National Center for Health Statistics. Intercensal estimates of the resident
population of the United States for July 1, 2000-July 1, 2009, by year, county, single-
year of age (0, 1, 2,.., 85 years and over), bridged race, Hispanic origin, and sex.
Prepared under a collaborative arrangement with the U.S. Census Bureau. Available
from: https://www.cdc.gov/nchs/nvss/bridged race.htm as of October 26, 2012,
following release by the U.S. Census Bureau of the revised unbridged intercensal
estimates by 5-year age group on October 9, 2012.

For 2010-2019, we obtained this information from the bridged race Vintage 2019
postcensal population file:

National Center for Health Statistics. Vintage 2019 postcensal estimates of the
resident population of the United States (April 1, 2010, July 1, 2010-July 1, 2019), by
year, county, single-year of age (0, 1, 2,.., 85 years and over), bridged race, Hispanic
origin, and sex. Prepared under a collaborative arrangement with the U.S. Census
Bureau. Available from: https://www.cdc.gov/nchs/nvss/bridged race.htm as of July
9, 2020, following release by the U.S. Census Bureau of the unbridged Vintage 2019
postcensal estimates by 5-year age group on June 25, 2020.

The children's populations by year and state, for July 1, were obtained by summing
across all counties and across the ages 0 to 17 inclusive.

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