&EPA
United States
Environmental Protection
Agency
Ground Water Rule (GWR) Monitoring Requirements
Water Systems With Their Own Source that Do Not Purchase Water or Sell Water to Another
Water System
See additional placards for requirements for wholesale and consecutive systems and those providing 4-log treatment of viruses and conducting
compliance monitoring
TOTAL COLIFORM-POSITIVE
You must conduct triggered sour
ground water well in response to a total coliform-positive
routine sample collected under the Total Coliform Rule (TCR)
unless you are conducting compliance monitoring for 4-log
treatment of viruses.
• Conduct triggered source water monitoring at each ground
water well WITHIN 24 HOURS1 of being notified of a total
coliform-positive routine sample.
• If you suspect the total coliform-positive routine sample
was caused by a distribution system problem, contact your
state to discuss options.
• Sample from each source in use at the time the total
coliform-positive routine sample was taken for every total
coliform-positive routine sample, unless the state has
approved representative monitoring.
- Your state may allow you to use representative source
water monitoring to reduce the number of samples
collected. Contact your state for approval.
• Sample for the state-approved fecal indicator. Contact your
state to determine which one(s) is approved and list here:
• Contact your state to ensure you are following the correct
sampling procedures and contact your lab to ensure you
are using the appropriate materials for monitoring. If your
system serves <1,000 people, you may be able to use TCR
repeat monitoring collected from a ground water source
to meet GWR requirements. Contact your state for more
information.
Laboratory Contact Information:
FECAL INDICATOR-POSITIVE
If your triggered source water
monitoring results are fecal
indicator-positive, you must:
• Notify your state and if
your state does not require
corrective action, collect
5 additional source water
samples WITHIN 24 HOURS.1
• The state may invalidate a
fecal indicator-positive sample
on a case-by-case basis.
Contact your state. If your
sample is invalidated, you
must resample for the same
indicator WITHIN 24 HOURS.1
• Notify the public with a Tier 1
Public Notice (PN) WITHIN 24
HOURS.
• Community water systems
must notify the public with a
Special Notice in your next
CCR.
ADDITIONAL MONITORING
If your fecal indicator source
water sample is positive then
the state may require additional
monitoring:
Take 5 samples from each source
that was fecal indicator-positive
WITHIN 24 HOURS.1
• If an additional sample is fecal
indicator-positive, you must:
- Notify the public with a Tier
1PN WITHIN 24 HOURS.
- Community water systems
must notify the public with a
Special Notice in your next
CCR.
- Consult with your state and
take approved Corrective
Action.
CORRECTIVE ACTION
You have to take correctiv
notified of a fecal indicator-positive additional
sample, a significant deficiency or if the state
requires it in response to a fecal indicator-
positive triggered or assessment sample.
1 A significant deficiency may be identified
during a sanitary survey or at any other time.
1 You are required to provide the state with
information requested to complete a sanitary
survey.
1 Within 30 days of notification you must
consult with your state to determine a
corrective action unless the state specifies a
corrective action.
1 Corrective Action options are:
- Correct all significant deficiencies
- Provide an alternate source of water
- Eliminate the source of contamination
- Provide 4-log treatment of viruses.
1 Within 120 days of notification you
must complete corrective action, or be in
compliance with a state-approved corrective
action plan and schedule.
1 If you fail to take corrective action, you will
incur a treatment technique violation and
must notify the public with a Tier 2 PN.2
1 Community water systems: If you have not
corrected the significant deficiency before
the end of the calendar year, you must notify
the public with a Special Notice in your next
CCR and repeat annually until the significant
deficiency has been addressed.
1 Noncommunity water systems: If you have
not corrected the significant deficiency within
12 months, you must notify the public with a
Special Notice and repeat annually until the
significant deficiency has been addressed.
Footnote 2: For this violation you must notify the state within 48 hours of the violation and provide a Tier 2 PN to the public within 30 days.
If you fail to conduct required monitoring within 24 hours of notification of a total coliform- or fecal indicator-positive sample, you must notify the public with Tier 3 PN (possibly in your next CCR).
The term "state" is used to refer to all types of primacy agencies including states, U.S. territories, Indian tribes, and EPA.
State/Primacy Agency Contact (name and phone number): Office of Water (4606M) EPA 816-F-10-058 www.epa.gov/safewater April 2010
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