What is a Contaminant?

A chunk of all natural, no artificial additives
chromite, or chromium ore.

When most people think of contaminants in their water, they think of some nasty chemical that’s polluting the land or water; something that leaked out of a tank somewhere; that was illegally dumped along some lonesome road in the middle of the night; or that is the result of some nefarious industrial process.  And in some instances, any or all of those scenarios may very well lead to contamination of the water supply.  But if you look at the EPA web site where they discuss and list all of the “contaminants” that they currently regulate in drinking water, (http://water.epa.gov/drink/contaminants/basicinformation/index.cfm ), you will also find a lot of compounds that are naturally occurring; no one dumped them, manufactured them, or otherwise “polluted” the environment with them.  They are every bit as much a part of the environment as the water itself.  That doesn’t mean they can’t be harmful – arsenic is naturally occurring, but ingest enough of it and it can still kill you.  Contrary to so many marketing campaigns that make you believe that “natural products” are somehow inherently safe, they can in fact be just as, if not more harmful than anything created by man. 

This issue comes up quite a bit in my interactions with the general public.  They may review their local water companies CCR and see fluoride listed, after which they call, quite upset, wanting to discuss the evils of adding fluoride to the water and how terrible it is that we do so. After I explain to them that there is no fluoride added to the water, but that a low level of fluoride is a natural occurring constituent of the groundwater in their local area, they are often quite surprised.  Just as surprising to me is that when they learn it’s naturally occurring, they don’t seem to think it’s a big a deal any more,  when in fact fluoride is fluoride no matter the source, whether it’s added by Mother Nature or the local water agency.  I guess Mother Nature just has better PR. 

Another good example regarding people’s misconceptions about contaminants is the current issue with hexavalent chromium.  Also known as chrome-6, hexa-chrome, Cr(6), or Cr(VI), this particular oxidative state of the element chromium can, under the right conditions and in sufficient concentration, be quite toxic.  Most people, in California at least, think of chrome-6 in terms of the whole debacle with PG&E contaminating the ground water near Hinkley, CA when they used a chrome-6 containing anti-corrosive chemical in the cooling towers at their natural gas transmission pipeline compressor station nearby.  But by far the greatest source of chrome-6 in the groundwater in California, and elsewhere, is from natural geologic formations containing chromium.  Unfortunately, this misunderstanding is one of many reasons that California may soon be saddled with a chrome-6 maximum contaminant level (MCL) that is excessive and unnecessary.

When I was taking botany in college, someone asked my professor what the definition of a weed was.  His response was that a weed is any plant that is somewhere you don’t want it to be.  Likewise for drinking water, saying something is a contaminant doesn’t mean it’s the result of some toxic spill or other pollution.  It means that, no matter what the source, it’s just something in the water that we don’t want there at more than a certain level, no matter what the source.

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

Sanitary Survey Checklist

The U.S. Environmental Protection Agency (USEPA) defines a sanitary survey of a water system as an “…on-site review of a public water system’s water source, facilities, equipment, operation, and maintenance.”  For a community water system, they require that a survey be done at least every three years.  They further go on to identify eight areas that are covered by the sanitary survey:

• water sources
• treatment
• distribution systems
• finished water storage
• pumps, pump facilities and controls
• monitoring, reporting and data verification
• water system management and operations
• operator compliance with state requirements 

Most if not all states will have similar requirements for periodic sanitary surveys covering these same elements as a part of implementing the Federal Groundwater Rule, compliance with which was to have begun on December 1, 2009. 

A large part of any sanitary survey is the inspection of treatment and distribution system equipment to ensure there are no defects that could compromise the quality or reliability of the water being served to the public.  Water systems should take a very proactive approach to these inspections, conducting periodic in-house inspections in addition to the inspections done by state or other regulators.  Many industry professionals think having an operator go to each plant site every day is sufficient, but operators are busy people and may not have time to inspect all the elements involved in a thorough sanitary survey.  And it’s always good to have someone besides the operator conduct the survey; a fresh set of eyes and a different perspective can often turn up issues that may otherwise have gone unintentionally overlooked.

It always helps in this sort of effort to have a good checklist you can work off of that covers all or most of the basic elements to be reviewed.  A checklist will help make sure nothing is missed and that the surveys are conducted consistently between plant sites and over time for the same plant site.  That last point is important to make sure any issues discovered in the survey are being addressed and not resulting in repeat deficiencies. To help me with the sanitary surveys I conduct in California, I went through a long list of references, including the California Title 22 regulations; Department of Water Resources well construction bulletins; and AWWA standards, and came up with my own checklist.  Those are available in this Excel file for you to look over, use, share, or modify to meet your needs.

This checklist also includes some basic health and safety elements, along with some hazardous material and hazardous waste elements that your local CUPA might inspect for.  For each item in the checklist, I've included the reference.   If there is no reference, that means either I couldn't find one, of that the item is just what I feel is a best management practice and doesn't have a regulatory reference.  If you can’t access the checklist for some reason, of if it’s in a format you can’t read, just contact me and I’ll try to provide the information for you in a different way.

I’d really appreciate any feedback you have on this checklist, including any suggestions for improvements or just comments on what you think in general. You can either comment right on this blog, or send me an e-mail.  Hopefully this check list will help keep your water systems running smoothly.

A Chloramine Primer

In my last post, I wrote about using the power of chlorine contained in sodium hypochlorite to inactivate microbial contaminants; give residual protection in the distribution system; and oxidize inorganic contaminants.  This time, we’ll look at using another chlorine containing compound, monochloramine, to do the first two of those three jobs.

The use of monochloramine as a drinking water disinfectant residual is nothing new; Denver, Colorado has been using it since 1917.  Monochloramine has a chemical formula of NH₂Cl.  It’s created by mixing the correct ratios of chlorine and ammonia, usually somewhere in a range from 3:1 to 5:1, chlorine:ammonia by weight.  The chemical reaction, using our old friend sodium hypochlorite for the source of the chlorine, looks like this:

HOCl + NH3 → NH2Cl + H2O

The reaction of monochloramine is also very dependent on the pH level.  Where a typical pH in any free chlorinated system is usually around 7, chloraminated systems usually have a pH closer to 8.

Monochloramine, also referred to as just chloramine, does not have the same inactivation or disinfecting “power” of free chlorine, due primarily to the fact that it is not as strong an oxidizer.  Some sources estimate that monochloramine is 200 times less effective as a disinfectant than free chlorine.  For that reason, chloramine levels need to be higher than free chlorine levels.  Many systems that run free chlorine often maintain a residual level of 0.5 to 1.0 mg/L, but chloraminated systems often run at 2.0 to 3.0 mg/L total chlorine. 

Without very careful monitoring of monochloramine formation, chloraminated systems can also have significant taste and odor issues.  This can result from the formation of di-chloramine (NHCL2) and tri-chloramine (NCL3), compounds similar to monochloramine but with additional chlorine atoms added.  These compounds have a very strong chlorine taste and odor.  Their formation is generally tied to an incorrect chlorine:ammonia ratio.  Specifically, there is too much chlorine for the given amount of ammonia.

Monochloramine

In any chloraminated system, there is also the presence of some level of ammonia.  The more closely controlled the process of chloramine formation, the less ammonia should be present.  But even with low levels of ammonia, under the right conditions, certain bacteria can use that ammonia for a food source and produce as by-products both nitrite and nitrate in a process called nitrification.  Nitrite in particular can become a problem because the Maximum Contaminant Level (MCL) is so low, only 1.0 mg/L.  Once the nitrification process gets established, it will also cause the chloramine residual level to drop, allowing for the formation of hard to treat biofilms in the distribution system.

With all of these issues with the use of chloramines, why would anyone want to use them?  Under the right conditions, a chloramine residual will last longer in the distribution system than a free chlorine residual.  If you have a very large distribution system, or very long transmission lines, using chloramines can provide better protection.  Another common reason for the use of chloramines is the fact that they can result in the formation of fewer disinfection by-products, particularly trihalomethanes (THMs) and haloacetic acids (HAAs).  The implementation of the Stage 2 Disinfectants and Disinfection Byproducts Rule resulted in a great number of utilities that could no longer meet the MCLs for THMs and HAAs like they could under the Stage 1 Disinfectants and Disinfection Byproducts Rule.  As a result, many of these utilities switched from free chlorine to chloramination.  Chloramines can also combat biofilms better than free chlorine, as long as nitrification is kept under control.  Free chlorine can’t penetrate through the outer layer of the biofilm very well, while monochloramine does a better job, resulting in increased inactivation of the organisms within the biofilm.  Since free chlorine and monochloramine each have their own pluses and minuses when it comes to combating biofilms and inactivating microorganisms, many utilities that routinely chloraminate make a yearly switch to free chlorine for several weeks to try and utilize the benefits of both types of disinfectants.

For a more detailed discussion of free chlorine, chloramines, and related disinfection topics, please check out these additional sources:

·          HACH has a very good discussion of all these topics located here - http://www.hach.com/DisinfectionSeries

·          HACH also has a very nice video on You Tube – http://www.youtube.com/watch?v=3rXZg6VDVRQ

A Bit About Sodium Hypochlorite Chemistry

In this post we’ll take a look at one of the major chlorine based disinfectants that we are most likely to deal with and how it reacts when we add it to water.  This will involve a bit of chemistry, but don’t be afraid.  It won’t hurt, I promise!

Sodium hypochlorite is a very commonly used disinfectant in drinking water systems.  The chemical formula for sodium hypochlorite is NaOCl, which means it has one sodium atom (Na); one oxygen atom (O); and one chlorine atom (Cl) all bound together.  This chemical is commonly purchased as a concentrated solution that contains about 12% sodium hypochlorite by weight.  So if you took 1 gallon of the stuff, which weighs about 10 pounds, then 1.2 pounds would be sodium hypochlorite, another 2 ounces would be sodium hydroxide (NaOH), and the rest would be water.

In a typical situation which we will use as an example, this concentrated chemical would be diluted.  It would be fed at a controlled rate into water being pumped from a well before it goes into the distribution system.  In this situation, the sodium hypochlorite reacts with water and forms two new chemicals: Hypochlorous acid (HOCl) and sodium hydroxide (NaOH).  The equation looks like this:

NaOCl + H₂O → HOCl + NaOH

Sodium hydroxide is a base, meaning it will raise the pH of the water.  This is the opposite of an acid, which lowers pH.  pH, without getting too technical, is just a scale to measure how acidic or basic something is.  Hypochlorous acid in water partially comes apart, or dissociates, into ions, which are just atoms or molecules that have an electrical charge.  In this case, it dissociates into a hydrogen ion (H⁺) and a hypochlorite ion (OCl⁻), like this:

Hypochlorite anion

HOCl → OCl⁻ + H⁺

The hypochlorite anion (a negative ion) that results is what we are after.  Because of its negative charge and the oxygen atom hanging off one end, this ion is very reactive and can cause changes to many other molecules it comes into contact with.  It is known as a strong oxidizer, which just means it can force changes to other atoms or molecules by either adding an oxygen atom to them, or by stealing electrons from them.  So what does that mean in more practical terms?  Let’s look at the function of the hypochlorite ion as a disinfectant – how does it actually kill bacteria?  It might surprise you to know that no one actually knows for sure.  There are lots of theories and the reality is probably a combination of some or all of them, but for all of our scientific prowess we still aren’t exactly sure.  Some of the ways in which it has been proposed that it works is by punching holes in the bacterial cell wall and membrane, causing too much water to flow in and other cell contents to flow out; slicing up the cell’s DNA; or inhibiting glucose metabolism, causing near instant starvation.  Sounds brutal!

Sodium hypochlorite is one way of using the oxidizing capabilities of chlorine based chemicals to, among other things, help keep our drinking water free of microbiological organisms.  Next time, we’ll take a look at chloramines and see how they perform a similar function.

As the Colorado Ebbs, Desal Must Flow

There has been quite a bit of news lately regarding the Colorado River: its over-subscription, its shrinking reservoirs, the possible battles to come.  I’ve been tweeting about a lot of that at @pvowell and @WeWork4Water:

The drying of the West; ""...a bumper harvest of lawsuits is approaching." #water  http://ow.ly/ntjVF

CA's goal should be no #water from CO River, filling the gap with desal. Other CO River states should support that. http://ow.ly/nmus2

What Seven States Can Agree to Do: Deal-Making on the #CO River. Great review of river policy & challenges. #water http://ow.ly/n6mEG

California has taken great advantage of the fact that the other basin states have historically under-utilized their allocations, using that “extra” water to satisfy an ever thirstier Southern California.  Now that those states are growing and utilizing their share of the river, Californiahas to cut back.  But with the coming realities of climate change making even California’s rightful share of the river unlikely to be deliverable, Californiawill have to come to grips with the fact that they can not rely on this source of supply in the future.  If Californiawere to completely forgo its Colorado River rights, allowing that water, or what there is of it, to be distributed to the other basin states, it would be a great help in alleviating their water shortage issues.  Of course, Californiawould have to come up with alternate supplies, or their equivalent. Continued and expanded conservation will have to be a part of that, but by itself it will not be, in fact can not be enough.  Continued further imports from Northern Californiaare also unreliable, and at best will need to be kept at current levels, not expanded.  But with a large and bountiful ocean at its door, Californiamust pursue desalination as a large part of its water supply.  Energy requirements for desalination continue to drop, approaching the same requirements to pump water from the Colorado.  Advances in technology for seawater intake are alleviating the issues of ingress and impingement that those intakes can cause; and similar advances in brine discharge can all but eliminate any ecological problems with that process.  By agreeing to reduce Colorado River usage through the development of desalination, other River basin states could also be brought into agreements to help pay for the development of the resource.  But first, California must come to grips with the fact that desalination will have to be a part of our water resources in the future and create a regulatory and legal environment that allows the permitting of these facilities without the endless lawsuits that currently plague every attempt to build a desalination plant.  As Californiawater professionals, everyone that works for water in this state must support the development of a robust desalination program to safe-guard our water future.