Sampling is the first and most important step in getting good data!

I have a friend who was a chemistry professor at a local college (he’s retired now), who used to live across the street from me.  One beautiful summer afternoon a while back, taking a break from our yard work, we stood out on the sidewalk chatting about, what else, collecting samples and the analytical process (did I mention we’re both tremendous geeks?).  He commented on how most people have no idea how critical getting a good sample is, and how hard it is in general to get really good data.  The analytical process for almost anything that we test for in the water business has so many steps, each of which compounds any deviations or discrepancies made in the previous steps, that it’s vitally important to be as accurate and precise in each step along the way in order to get good, meaningful data in the end.  And of course that whole process starts with what is the most crucial action of all – taking the sample.  That’s why Title 22 California Code of Regulations, §64415 states that sampling for drinking water systems shall be “performed by a water treatment operator certified by the Department … or by personnel trained to collect samples and/or perform these tests by the Department, a certified laboratory, or a certified operator.”  All of that sampling needs to be done by trained professionals who know what they’re doing.  And it’s not enough to be trained once and then go on your merry way.  Even if you’ve been sampling for years, it pays to refresh your training now and then, because with anyone, errors and missteps can creep into our practices over time without our ever noticing. 

The California-Nevada Section of AWWA has a short book called Water Quality Sampling Guidelines that is getting a bit old, having been published in 2005, but is still a pretty good reference if you have a question or just need a refresher.  The book isn't listed for sale on their web site - http://ca-nv-awwa.org/canv/web/ - but I did call them a while back and they were able to get me a copy for $20.  There are also sampling training references and videos on the web.  A few of them are:

·          The Maryland Department of the Environment sampling video - http://www.mde.state.md.us/programs/Water/Water_Supply/Pages/MCET_DWS_Video.aspx

·          Sampling Drinking Water for Chemical Parameters from NovaTrainingOnline - http://www.youtube.com/watch?v=bZxMuJD0xSo

·          New Mexico Water Sampling Certification Study Guide - http://www.nmenv.state.nm.us/swqb/FOS/Training/WaterSamplingStudyGuide/WaterSamplingStudyGuide.pdf

·          Indiana Water Operator Training Manual - http://www.indianaruralwater.org/IRWA/pages/documents/INDIANA-WATEROPERATORTRAINING-MANUAL.pdf

Your states Rural Water Association; State and County Departments of Public Health; and your local laboratory can also be good sources of information on taking samples.  Sampling is the first and most important step in getting good analytical data about your water system, so be sure to keep your skills fresh and up to date.

The Revised Total Coliform Rule

Every week, many of the operators reading this article spend their morning driving from sample station to sample station, very carefully filling little 100 mL bottles with water from their distribution system.  Once per quarter or per month, they probably do the same thing for the water from each and every operating well.  And if they work at a surface water treatment plant, they take a great many more of those samples.  They cap the bottles, label them appropriately, and prepare them for transport to the laboratory where they will be tested for Total Coliform (TC) Bacteria.  If the test is positive, then the sample will also be tested for a specific TC bacteria, Escherichia coli, more commonly known as E. coli.  So what is a coliform bacterium and why do we test for it?  Coliform bacteria are defined as rod-shaped Gram-negative non-spore forming bacteria which can ferment lactose with the production of acid and gas when incubated at 35-37°C¹.  That’s a mouthful!  In other words, a coliform bacteria is one that gives a positive test result; not a real meaningful definition.  In theory, the coliform test is used to try and detect bacteria that may be present because of contamination by animal feces, sewage, or sewage contaminated water.  A great many of the bacteria that live in the gut of mammals like humans are coliform bacteria.  However, coliform bacteria can and do live just about anywhere: in the soil; in surface and groundwater; in and on plants, flowers and fruits; everywhere!  So just because there may be a positive coliform sample doesn’t mean that the water is contaminated.  It is just an indicator that there could possibly be a problem, and that you should do some investigating to see if there are any problems you weren’t aware of in your system: maybe a leak, an unprotected backflow situation, low chlorine residuals, etc.   We are required to test for these bacteria in the distribution system by the Total Coliform Rule (TCR), and there are very specific steps that must be taken if a test result is positive, such as taking repeat samples.  The TCR has been revised recently to better reflect the fact that a positive result does not necessarily mean there is contamination.  On February 13, 2013, EPA published in the Federal Register the revisions to the TCR (RTCR), which are now set to take effect in March 2016.  Key provisions of the revised TCR include²:

·         Maintains the routine sampling structure of the original TCR

·         Reduces the required number of follow-up samples (repeat and additional routine) for systems serving ≤1,000

·         Like TCR, reduced monitoring is available for small systems

·         Provides more stringent criteria that systems must meet to qualify for and stay on reduced monitoring

·         Requires small systems with problems to monitor more frequently

·         RTCR requires Public Water Systems to investigate the system and correct any sanitary defects found when monitoring results show the system may be vulnerable to contamination

·         Systems must conduct a basic self assessment (Level 1) or a more detailed assessment by a qualified party (Level 2) depending on the severity and frequency of contamination

·         Failure to assess and correct is a Treatment Technique (TT) violation

·         Notify public within 24 hours if system confirms fecal contamination (E. coli)

·         Total Coliform MCL/ acute violation is eliminated

·         Notify public within 30 days if system does not investigate and fix any identified problems

·         Notify public yearly regarding monitoring, reporting and recordkeeping violations

The Revised Total Coliform Rule is a good thing, no doubt about it.  It removes stringent regulations regarding total coliform bacteria, which turned out to be not as good an indicator of fecal contamination as it was once thought.  Instead, it relies more heavily on the investigation and correction of distribution system issues that could potentially be a source of contamination into the system.  And maintaining the treatment and distribution systems are, of course, what those same operators who go out and collect all these samples do on an every day basis anyway.

For more information on the Revised Total Coliform Rule, go to EPAs website at

http://water.epa.gov/lawsregs/rulesregs/sdwa/tcr/regulation_revisions.cfm

1.       American Public Health Association, Standard Methods for the Examination of Water and Wastewater, 19th ed., APHA, Washington, DC, 1995

2.       http://water.epa.gov/lawsregs/rulesregs/sdwa/tcr/upload/rtcrwebinar41013-1-2.pdf