[Dwopcert] August Monitoring Tips

Mon Aug 2 07:36:40 MST 2010

*NEW* ADEQ Monitoring Tips of the Month - August 2010


All sizes of Community and Non-transient Non-community water systems that add a disinfectant to the drinking water (or receive finished treated water thru a consecutive connection or via a water hauler) during any part of the drinking water treatment process, must sample and report Maximum Residual Disinfectant Levels (MRDL).


NOTE: If you are a Transient Non-community system, this tip does not apply to your system unless you use chlorine dioxide.


Maximum Residual Disinfectant Levels (MRDL) are also referred to as the 'chlorine residual':

*         Regulations are found in 40 CFR §141.130 - §141.134 / A.A.C. R18-4-114.

*         Samples reported quarterly.


Disinfectant Residual


MCL (mg/L)

(as a running annual average)


4.0 (as Cl2)


4.0 (as Cl2)

 Chlorine Dioxide

0.8 (as ClO2)


*         If a PWS uses chlorine or chloramines; take monthly at the same time and location of each Total Coliform sample taken in the Distribution System.

*         Use report 18A: http://www.azdeq.gov/environ/water/dw/download/18a.pdf


*         If a PWS uses chlorine dioxide; take daily at the Entry Point to the Distribution System.

*         Use report 18B: http://www.azdeq.gov/environ/water/dw/download/18b.pdf


Contact the Rule Specialist if you have any questions: Louis Notah 602-771-4626 or ln1@azdeq.gov


All sizes and three types (Community and Non-community) of public water systems, including consecutive systems, that use wells or other ground water sources are subject to the triggered source water monitoring under the Ground Water Rule (GWR), in response to a positive routine Total Coliform Rule sample .


Triggered Source Water Monitoring under the GWR:

*	If you get a total coliform positive sample under the Total Coliform Rule, then each well that contributed to the finished water in the distribution system that tested positive, must be sampled within 24 hours. 
*	GWR raw water samples (untreated water sampled at the wellhead) must be analyzed for one of the three fecal indicators, not just total coliform: 

	*	E. coli 
	*	Enterococci 
	*	coliphage 

*	Monitoring requirements are in addition to the Total Coliform Rule sampling. 
*	If any raw water wellhead sample is positive for one of the three fecal indicators (but not total coliform positive and fecal indicator negative) then you must take four more samples at each well, for any well that was total coliform positive, within 24 hours. 
*	Any fecal indicator positive sample is an acute 24-hour public notice. 
*	More information on the GWR and Public Notice templates can be found at this link: http://www.azdeq.gov/environ/water/dw/gw_rule.html 


If you have any questions, please contact the Drinking Water Monitoring and Protection Unit Manager, Donna Calderon, at 602-771-4641 or dml@azdeq.gov, or the Total Coliform Rule Specialist, Suzanne Price, at 602-771-4560 or sop@azdeq.gov for further assistance.


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