In this month’s edition of the Water Technology^® Contaminant Insider, Joseph Cotruvo, Peter Meyers and Gary Schreiber share their thoughts on E. coli and the U.S. Environmental Protection Agency’s Total Coliform Rule.

Water Technology: Is the EPA’s Total Coliform Rule (TCR) sufficient to protect the population from an outbreak? Are new regulations needed specifically for E. coli?

Joseph Cotruvo: Total coliforms (TC) are considered “indicator” organisms because they are measured as surrogates for the possibility that sewage-related pathogen contamination may be occurring; however, there are many sources of TC in the environment that are not directly related to sewage and potential pathogens. Total coliforms are ubiquitously present in the environment in very large numbers — much greater than the pathogenic bacteria or viruses. The E. coli or fecal coliforms are considered to be more direct indicators of recent possible human sewage contamination, and the potential for contamination by pathogenic bacteria or viruses. They are not good indicators for protozoa like giardia or cryptosporidium because they are fragile and die off fairly quickly (hours to days) and are easily disinfected by chlorine. There are also some known environmental E. coli that are not sewage related.

The total coliform regulations are protective because they are very conservative by representing a large group of organisms, the vast majority of which are not pathogens. They would also include E. coli, the vast majority of which also are not pathogens. The risk is more a function of sampling frequency and location which varies by system size. At least 480 samples per month are required in very large water systems; the smallest systems (25 to 1,000 population) have a monitoring requirement of once per month. Due to the conservatism of the TC rule the regulation allows up to 5 percent positive total coliforms samples per month. However, each positive sample requires follow-up resampling upstream and downstream from the sampling site in the line, and each positive coliform sample requires a check for fecal coliforms or E. coli; the requirement is 0/100 ml. E. coli or fecal coliform positives can lead to boil water notices. However, the TC/Fecal coliforms test requires about 24 hours until results are known, so that delay means that real time data are not available.

Peter Meyers: It is impossible to prevent every potential outbreak by means of inspections. Incentives don’t help when a problem is caused by aging infrastructure and there isn’t enough money to replace the treatment and/or distribution system. Having said this, we still need to minimize dangers to public health and the EPA’s Total Coliform Rule appears to be a reasonable attempt at doing this.

Gary Schreiber: I have every confidence in the “We are your Government and we are here to help you” program. EPA does a good job of protecting the population, but not perfectly. I, for one, consider the TCR as a good rule. It’s not perfect, but it seems to be working. Can it be improved? Not by me. Are new regulations need? The last thing we need is more government regulation. What is needed is more of us in the water treatment industry being aware of the many and sundry types of problems and more proficient on how best to fix them.

WT: How important is a “multi-barrier approach” when dealing with waterborne pathogens such as E. coli?

JC: The multi-barrier approach is essential to provision of safe drinking water because it is preventive rather than reactive. Bacteria (including E. coli) and viruses are easily prevented from entering finished drinking water by combinations of filtration and disinfection for surface waters, and disinfection of groundwaters that are not under the direct influence of surface waters. However, current disease outbreak data show that most outbreaks are attributed to distribution system post contamination after the water has left the treatment plant. These can occur from cross connections, back siphonage or leaks. Disinfectant residuals are intended to prevent or reduce regrowth of HPC type microorganisms in the distribution system, but the small residual concentration could not be expected to be able to cope with a bolus of sanitary contamination from the above causes. However, loss of a disinfectant residual can be an indication that such post contamination has occurred.

PM: Assuming there is one treatment step that is 100 percent effective then more aren’t needed. However, if no totally effective process is available then more than one partially effective treatment step is better than nothing.

I only balance my checkbook once because if I balance it twice I get two different sums and then I am confused and don’t know which is correct. That’s why I always leave a reserve in the exchequer. Maintaining a decent chlorine residual might be our best defense.

GS: Very important. The end user of a water needs to be protected in the best way possible. Therefore, my understanding of the “multi-barrier approach” is that one needs to look at the end user’s POE or POU and ensure at that location that there is sufficient protection to prevent re-infestation by any of the potential re-infestation sources. Re-infestation can happen anywhere in a distribution system after the primary protection has been accomplished. One example is in a municipal water treatment plant where they inject a disinfectant or in any other way treat the water to prevent re-infestation and nothing after that is done such as in a home or business where that treated water is used but has not been subjected to further treatment. Re-infection can occur by someone causing re-infection out in the distribution system. Re-infection can be caused by a broken main that is not properly fixed and re-disinfected by the servicing people.

Another example is for a private well system that may be continuously disinfecting by some method at the POE to the home or business but not adequately monitoring the treatment system that is in use. Either the current system fails and re-infection occurs without the user's knowledge or re-infection is caused unknowingly by the end user at some POU point in the home or business. Multi-barrier would be a UV/submicron filter system installed on the critical POU or a UF or MF or RO Drinking Water system installed at a critical POU.

One can do “overkill” by having more multi-barriers but if the cost is justified then install an overkill multi-barrier system or, at a minimum, have a good monitoring of the primary treatment system in place.

	Dr. Joseph Cotruvo is president of Joseph Cotruvo and Associates, LLC, Water, Environment and Public Health Consultants. He holds a Ph.D. in Physical Organic Chemistry and is a member of the World Health Organization’s Guidelines for Drinking-water Quality Committee and expert advisory groups on drinking water quality, desalination, wastewater and water reuse. He is a former director of the USEPA Drinking Water Standards Division.
	Peter Meyers is technical director for ResinTech Inc. of West Berlin, N.J. He has more than 35 years of experience covering a wide range of ion exchange applications from demineralizers, polishers and softeners to industrial process design and operation.
	Gary Schreiber, CWS-VI is the midwest sales manager for The Purolite Co., a global ion exchange resin manufacturer. He has 38 years of experience in the water treatment industry and is a member of the Water Technology Editorial Technical Advisory Board.