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PCWS Water Quality Monitoring - Total Coliform

 

USEPA Quick Reference Guides:

Total Coliform Rule 

Ground Water Rule

Ground Water Rule Sample Collection and Transport

What are Coliform bacteria?

 

Coliforms are bacteria that are naturally present in the environment and used as an indicator that other, potentially harmful, bacteria may be present.  Total coliforms in the distribution system may indicate a potential pathway for contamination but in and of themselves do not indicate a health threat. However, Coliforms found in more samples than allowed are a warning of potential problems.

What is E. coli?

 

Fecal coliform and E. coli are bacteria whose presence indicates that water may be contaminated by human or animal wastes. Microbes in these wastes can cause short term effects, such as diarrhea, cramps, nausea, and headaches. They may pose a special health risk for infants, young children, and people with severely compromised immune systems

  

What are the sampling requirements for Coliform bacteria?

 

The EPA Total Coliform Rule requires that all public water systems (the three types include: Community, Non-Community Non-Transient (NTNC); and Transient Non-Community (TNC)) perform routine monitoring for total Coliform bacteria.  Systems must collect at least one coliform sample per month (Community) or quarter (NTNC, TNC) depending on the population served1 and type of system.2 Guidance for determining your water system type: http://drinkingwater.vt.gov/drinkingwatersystems.htm.  

What to do if Coliform is detected in a sample at your system?

If total coliform or E. coli is detected in a routine (RT) sample from your water system, you need to immediately contact the TCR Compliance Officer of the Drinking Water and Groundwater Protection Division and collect FOUR repeat (RP) samples.  The purpose of the repeat samples is to help determine whether there is a contamination problem at the system and, if so, to help identify the source of contamination.  The four repeat samples should be collected within 24 hours from the time you learn about the positive coliform result and should include:

  • One repeat sample collected from the same tap as the original sample.
  • One repeat sample collected within five service connections upstream.
  • One repeat sample collected within five service connections downstream.
  • One triggered (TG) ground water source sample from each source in use at the time the total coliform-positive was collected.*  (EPA Groundwater Rule)

* Systems using surface water must collect a 4th repeat sample from distribution. 

You will need to contact an approved laboratory to obtain the proper sample bottles.

The next steps you must take depend on the results of the repeat samples.  These steps are outlined in the bullet list below as well as in this flow chartRegardless of the results of the repeat samples, you must collect FIVE ‘temporary’ routine samples during the calendar month following the initial coliform detect.  These samples may be collected any time during the month.

  • If coliform is not detected in any of the repeat samples, no further action is required other than the five routine samples during the following calendar month.
  • If coliform is detected in only one repeat sample, you must post public notice within 24 hours and will be issued a non-acute maximum contaminant level (MCL) violation.  A boil water notice is not required.
  • If coliform is detected in two or more repeat samples, you must post public notice within 24 hours and will be issued a non-acute MCL violation and a boil water notice directive.
  • If E. coli was detected in the original routine sample, and a resample cannot be collected within 24hrs, you must issue a boil water notice directive.  
  • If E. coli was detected in the original routine sample, and coliform is not detected in a resample performed within 24hrs, no further action is required other than the five routine samples during the following calendar month.
  • If E. coli was detected in the original routine sample and coliform is detected in one or more repeat samples, you must post public notice within 24 hours and will be issued an acute MCL violation and a boil water notice directive.
  • If E. coli is detected in any of the repeat samples you must post public notice within 24 hours and will be issued an acute MCL violation and a boil water notice directive.

If coliform is detected in any of the repeat samples, the Division recommends that the system seek technical assistance to help locate and eliminate the source of contamination.   Free technical assistance is available to Transient Non-Community (TNC) systems from Vermont Rural Water Association, a non-profit organization that provides onsite assistance to water systems, at (800) 556-3792.

Questions regarding Total Coliform monitoring should be directed to the TCR Compliance Officer of the Drinking Water and Groundwater Protection Division.

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1 – Monthly sampling requirements are based on population served. Link to Table.

2 – Systems using surface water or groundwater sources under the direct influence of surface water (GWUDI) must monitor monthly or more frequently, as directed by the State.

 

 

 

drinkingwater.vermont.gov   groundwater.vermont.gov   septic.vermont.gov wastewater.vermont.gov
VT DEC Drinking Water and Groundwater Protection Division 1 National Life Drive, Main Building, 2nd Floor  Montpelier, VT  05620-3521
Telephone toll-free in VT: 800-823-6500 or call 802-241-3400    Fax: 802-828-1541

 

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