The
background
papers
on
the
candidate
national
program
priorities
are
intended
to
initiate
further
discussion.
When
priorities
are
selected
more
detailed
strategies
with
in­
depth
background
information,
numerical
targets,
schedules,
milestones
and
performance
measures
will
be
developed.
______________________________________________________________________________

December,
2003
Page
1
of
2
Proposed
Priority
Safe
Drinking
Water
Act
(
SDWA)
­
Microbial
Plus
Universe
&
Types
of
Facilities
This
potential
priority
includes
public
water
systems
(
PWSs),
defined
at
40
C.
F.
R.
§
l41.2
III.
While
public
water
systems
are
identified
under
SIC
code
4941
North
American
Industry
Classification
System
(
NAICS
221310),
they
may
also
be
located
at
facilities
identified
under
other
SIC
codes
if
the
facility
produces
drinking
water
onsite.
EPA`
s
Safe
Drinking
Water
Information
System/
Federal
version
(
SDWIS/
FED)
database
currently
maintains
an
inventory
of
approximately
168,000
active
PWSs,
more
than
90
percent
of
which
serve
3,300
or
fewer
users.
The
various
drinking
water
regulations
define
systems
serving
3,300
or
fewer
users
as
small
systems.
There
are
nearly
1,000
PWSs
on
Indian
lands,
most
serving
fewer
than
3,300
people
and
none
serving
more
than
10,000.

Geographic
Range
Nationwide.

Environmental
Risks
Bacteria,
protozoans
and
viruses
are
all
microbial
pathogens
of
concern.
Microbial
contamination
can
be
present
in
source
water
(
surface
water,
ground
water,
or
purchased
finished
water),
can
be
introduced
by
unsanitary
conditions
at
treatment
or
storage
facilities,
and
can
enter
the
drinking
water
delivery
infrastructure
through
infiltration
or
cross­
connections.
Generally
speaking,
the
risk
of
microbial
contamination
is
highest
during
warm
months
at
systems
that
use
surface
water
as
a
source.
Because
nitrates
are
a
primarily
component
of
chemical
fertilizers
and
are
also
concentrated
in
animal
and
human
wastes,
nitrate
contamination
of
drinking
water
is
most
likely
to
occur
in
agricultural
areas,
or
as
a
result
of
improper
biosolids
application
near
a
public
water
system's
water
source.

1.
Acute
Contaminants
 
Microbial
pathogens
or
nitrates
in
drinking
water
can
produce
immediate
severe
health
effects,
especially
in
children,
the
elderly,
and
persons
with
compromised
immune
systems.
Adverse
health
effects
of
microbiological
contaminants
can
include,
fever,
jaundice,
pneumonia,
vomiting,
diarrhea,
dehydration,
and
death.
Nitrate
taken
into
the
body
is
converted
to
nitrite,
which
obstructs
the
blood's
ability
to
carry
oxygen.
This
can
produce
serious
illness,
particularly
in
infants,
characterized
by
shortness
of
breath,
bluish
skin
and,
in
extreme
cases,
death
by
suffocation.

2.
Substantial
Endangerment
 
Many
contaminants,
microbial,
chemical,
or
radiological,
regulated
The
background
papers
on
the
candidate
national
program
priorities
are
intended
to
initiate
further
discussion.
When
priorities
are
selected
more
detailed
strategies
with
in­
depth
background
information,
numerical
targets,
schedules,
milestones
and
performance
measures
will
be
developed.
______________________________________________________________________________

December,
2003
Page
2
of
2
or
unregulated,
may
constitute
an
imminent
and
substantial
endangerment
to
public
health
if
present
at
significant
levels
in
drinking
water.

3.
Cumulative
Risks
 
Public
water
systems
in
non­
compliance
with
multiple
non­
microbial
rules
(
e.
g.,
a
radionuclide
Maximum
Contaminant
Level
(
MCL)
and
a
barium
MCL)
or
that
have
combinations
of
multiple
types
of
violations
(
e.
g.,
violations
of
a
MCL
or
treatment
technique
plus
a
monitoring/
reporting
violation)
may
pose
a
higher
cumulative
risk
to
public
health.
Additionally,
systems
located
within
the
same
geographic
area
may
experience
similar
violations
thus
posing
another
type
of
cumulative
risk
for
users
who
get
their
water
from
more
than
one
system
(
e.
g.,
people
whose
drinking
water
at
work
and
home
are
supplied
by
different
systems).

Noncompliance
Information
The
Total
Coliform
Rule,
which
applies
to
all
public
water
systems,
historically
is
the
drinking
water
rule
most
frequently
violated.
Almost
44,000
of
the
more
than
110,000
drinking
water
violations
reported
in
EPA's
2001
National
Public
Water
Systems
Compliance
Report
were
violations
of
the
Total
Coliform
Rule.
Another
5,000
of
the
drinking
water
violations
were
violations
of
the
Surface
Water
Treatment
Rule.
This
means
that
more
than
56
percent
of
all
drinking
water
violations
in
calendar
year
2001
were
violations
of
microbial
rules.
In
the
same
year,
there
were
more
than
9,100
violations
of
nitrate
requirements.
In
FY
2005,
by
focusing
on
violations
of
the
Total
Coliform
Rule,
the
Surface
Water
Treatment
Rule,
the
nitrates
requirements,
and
the
newly­
effective
requirements
of
microbial
rules
such
as
the
Interim
Enhanced
Surface
Water
Treatment
Rule,
the
Filter
Backwash
Rule,
the
Long
Term
1
Enhanced
Surface
Water
Treatment
Rule,
and
the
Stage
1
Disinfectants
and
Disinfection
Byproducts
Rule,
EPA
would
likely
be
addressing
approximately
two­
thirds
of
all
drinking
water
violations.

Of
the
41,300
PWSs
for
which
the
states
reported
a
violation
of
a
health
based
standard
or
significant
monitoring
and
reporting
requirement,
almost
39,400
were
small
systems
serving
3,300
or
fewer
users.
