In the Main - A technical assistance newsletter for Public Water Suppliers
August 2009

Reminder: GWR sampling and compliance requirements are effective December 1, 2009. For more detailed information, factsheets, forms, presentations, and training information, go to: http://www.mass.gov/dep/water/drinking/systems.htm#gwr or http://www.masmallwatersystem.org. PWSs are strongly encouraged to read the MassDEP factsheet which contains rule basics.

Q: When is a PWS required to either install disinfection/treatment or increase disinfection/treatment under the GWR?

A: If a PWS has multiple positive fecal indicator (E. coli or enterococci) detections in their well water, AND the source of contamination cannot be identified and eliminated AND/OR a problem at the PWSs that might lead to contamination cannot be identified or fixed, THEN the PWS is required to either install disinfection/treatment or increase their existing disinfection/treatment to ensure 99.99% of pathogens (viruses) are eliminated from the water.  This is referred to as 4-log treatment. 

Q: How can a PWS determine if they currently have 4-log treatment?

A: MassDEP estimates that most PWSs do not have 4-log treatment of viruses.  PWSs that are chlorinating are required to complete GWR Form A - Log Credit Determination which is available online at http://www.mass.gov/dep/water/drinking/systems.htm#gwr. By completing the form, the PWS will estimate the log treatment provided at their facility.  PWSs wishing to receive formal approval and be recognized for 4-log treatment must submit additional supporting documentation to their regional office. If approved, the PWS must conduct compliance monitoring to prove that the treatment is operating properly.  The PWS will not be required to conduct GWR source water monitoring.

Q: What is triggered source water monitoring - also referred to as source water monitoring? 

A: Every time a PWS receives notice from their lab of a total coliform positive TCR distribution system or source sample, the PWS must collect a GWR triggered source sample within 24 hours of the notice and test it for the appropriate fecal indicator (E. coli or enterococci). If that sample tests positive, the PWS must collect an additional five samples within 24 hours and test them for the fecal indicator. All PWS must conduct source water monitoring unless they are treating/disinfecting to meet 4-log requirements described above. The majority of MA systems do not currently meet 4-log treatment requirements as described above and therefore will be required to conduct source water monitoring.

Q: Which fecal indicator should the PWS test for?

A: All non-community and community PWSs serving 3,300 or fewer test for E. coli. All community systems serving greater than 3,300 test for E. coli IF E. coli is detected in the original TCR sample.  IF only total coliform is detected in the original TCR sample, the PWS tests for enterococci.

Q: If a PWS has a single fecal indicator positive in ANY source water sample (this includes source samples collected under the GWR and the Total Coliform Rule (TCR)), is Tier 1 public notice required?

A:Yes. Please work closely with your regional office when issuing Tier 1 notice language. See website for regional MassDEP contacts.

Q: Are PWSs with multiple wells required to collect samples at each well every time GWR sampling is required?

A: Yes - unless the PWSs submits a "Triggered Source Water Monitoring Plan" (which is available on line at http://www.mass.gov/dep/water/drinking/systems.htm#gwr) by September 1, 2009 for review and approval by MassDEP. Details of the plan should include a map with system components and a written explanation/proof that the wells: (1) serve independent sections of the distribution system with specific TCR monitoring sites, or (2) are representative of the same water quality, or (3) discharge to a common header prior to entering the distribution system.  For more details, please speak with your regional GWR contact.  PWSs that do not submit a plan and receive MassDEP approval by December 1, 2009 must collect a GWR triggered source sample at EACH well until approval is granted.

Q: Does the GWR triggered source water monitoring replace any TCR monitoring requirements? Are TCR requirements changing?

A: No and no.  GWR sampling does not replace routine and repeat bacteria sampling for TCR compliance.  PWSs should continue to take TCR samples and follow-up - business as usual.  TCR sampling requirements are not changing.  However, the fecal coliform analysis is being eliminated from the TCR.  When a TCR sample is total coliform positive, it must be analyzed for E. coli beginning December 1, 2009.

Q: Are PWSs required to do anything before the rule effective date of December 1, 2009?

A: Yes.  By September 1, 2009, all PWSs must complete GWR Form B - Immediate & Long-Term Response to Fecal Contamination (which is available on line at http://www.mass.gov/dep/water/drinking/systems.htm#gwr). Also by this date, all chlorinating PWSs must complete GWR Form A - Log Credit Determination.  As described above, those PWSs with multiple wells may wish to submit a Triggered Source Water Monitoring Plan.   By December 1, 2009, all PWSs must install a raw water sample tap.  And, all community and non-transient non-community systems must install a disinfection chemical injection port for adding emergency disinfection when required by MassDEP. 

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Ground Water Rule Questions & Answers

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MWWA Meeting & Education Seminars

Consultant's Chemical Checklist

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Changes to the Total Coliform Rule