Eliminating Chlorine Residuals from Tap Water

By Kelly A. Reynolds, MSPH, PhD

Drinking water from the tap is not sterile but is regulated to a level of acceptable risk so that infections from microbial exposures and illnesses from chemicals occur at very low levels. In the US, acceptable risk goals are set at one infection per 10,000 persons per year for microbes and as low as one in a million cases of cancer from chemicals, including added disinfectants. The question is how to ensure the safety of drinking water considering that common water treatmentprotocols inherently create additional health risks. Recent studies compare differences among various countries in water quality management, while exploring whether or not carcinogenic chlorine residuals can be safely excluded from municipal tap water supplies.

Water treatment in developed countries
Microbial contamination of drinking water post-treatment is a major concern for municipalities. The US has relied on a multi-barrier approach to drinking-water treatment, so that the chain oftreatment applications can make up for any upstream deficiencies. Following source protection and municipal treatment, the final step in US water treatment is secure distribution to consumer taps. Ideally this is accomplished with clean, contained distribution piping. Unfortunately, the USdistribution system is aged, leaky and plagued with biofilm formation, offering nutrients and protection to harmless and harmful microbes alike. Thus, the addition of a disinfectant residualwithin the distribution system is standard protocol.

Worldwide, many countries (including the US and the UK) require municipalities to add disinfectants such as chlorine or chloramine to the distribution system. This action creates the need to manage DBPs via rapid circulation in the system or water storage practices to minimize stagnant water zones where disinfectants are further added to retard microbial growth.
Other countries (including the Netherlands, Switzerland, Austria and Germany) do not rely on disinfectant residuals in the distribution system. But how can these countries ensure safe drinking water at the tap without using this common final barrier? The answer to this question lies in the system engineering that is designed to provide more advanced water treatment pre-distribution, effectively reducing biodegradable compounds and biofilm production. A reducedbiofilm means reduced microbial growth and pathogen survival in the pipes. In countries that do not use residual disinfectants, distribution infrastructure is well-maintained and managed to utilize smaller pipes, rapid circulation and proactive flushing, combined with monitoring and rapid repair practices.

Pros and cons of the chlorine residual
Disinfection of water with chlorine has been touted as one of the greatest public-health interventions of the century, preventing epidemic waterborne outbreaks such as cholera, typhoid and dysentery. Water disinfection, however, impacts the sustained microbial population (i.e., the system’s microbiome) and general water chemistry, resulting in both positive and negative changes relative to water quality and safety.
DBPs are created during the production of drinking water when chemicals such as chlorine,ozone, chloramines, etc. react with natural organic materials, bromide, iodide and other manmadecompounds. The resulting products (more than 600 identified), including THMs and HAAs, are toxic to humans and animals and have been reported in drinking-water systems worldwide.Corrosion and adverse taste are other undesirable byproducts of chlorine residuals in tap water.
Although little information exists on the potential toxicity of DBPs in drinking water, exposures have been linked to a variety of health issues, including liver, kidney and central nervous system problems. Epidemiological studies have associated lifetime exposure to chlorinated water with increased risk of bladder and colorectal cancers.(1) The trade-off of not using disinfectant residuals, however, could mean an increased risk of exposure to microbial pathogens.
Contamination in the distribution system occurs due to breaks, leaks, cross-connections, pressure differentials and other events leading to intrusion of hazardous microbes and chemicals.(2) At least 20 percent of distribution mains are reported to be below the water table and all systems have submerged pipes at some time throughout the year which provides additional opportunity for intrusion of exterior water under low- or negative-pressure conditions. Negative hydraulic pressure can draw pathogens from the surrounding environment into the water supply whereresidual disinfection efficacy is uncertain and variable due to changes in water age, residence time, flow velocity, etc. Outbreaks occur following external contamination in the distribution system despite the presence or requirement of residual disinfectant. Research suggests that typical residual chlorine levels (0.5 mg/L) do not provide significant inactivation of all pathogensduring intrusion events, especially protozoan and viral pathogens.(3)

Can the US eliminate a chlorine residual in tap water?
Numerous studies suggest that the presence of chlorine residual does little to prevent waterborne outbreaks. A comparison of use/non-use of chlorine residual further indicates that systems with a residual disinfectant do not necessarily have fewer outbreaks.(4) Elimination of achlorine residual in the US is unlikely given the significant lack of investment in infrastructure maintenance. Compared to the Netherlands, which has recently replaced much of its distribution piping, the US distribution system is decades older and in dire need of repair. While researchers conclude that delivery of water with the same safety level is possible and that the US should move toward a disinfectant residual-free system, a whole new set of safeguards must first be in place. Such modifications will substantially drive up the cost of drinking water, a consequence other countries have accepted, given that water costs two to three times more in western Europe.(2)

Conclusions
The US is far from reaching a residual-free tap water supply. The trade-off of not adding chlorineand risking the consequences of acute microbial illness is currently not beneficial. Therefore, consumers should consider the benefits of keeping chlorine residuals in tap water but controlling exposures to harmful contaminants at the tap. The most widely applied POU water treatment for DBP removal is activated carbon filtration. NSF-certified POU devices are required to remove 95 percent of a 300 µg/L chloroform influent challenge concentration, resulting in a 15-µg/L maximum effluent concentration. In the US and countries with similar treatment design, POU devices offer the best available treatment at the tap to mitigate DBP exposures, particularly given system variability and the uncertainties of future municipal treatment modifications.

References
(1) World Health Organization. IARC monographs on the evaluation of carcinogenic risks to humans. (2014).
(2) Rosario-Ortiz, F. et al. How do you like your tap water? Science, 351, 912–4 (2016).
(3) Reynolds, K.A.; Mena, K.D. and Gerba, C.P. Risk of waterborne illness via drinking water in the United States. Rev. Environ. Contam. Toxicol. 192, 117–58 (2008).
(4) Rosario-Ortiz, F. and Speight, V. Can drinking water be delivered with-out disinfectants likechlorine and still be safe? The Conversation (2016). at <http://theconversation.com/can-drinking-water-be-delivered-without-disinfectants-like-chlorine-and-still-be-safe-55476>

About the author
Dr. Kelly A. Reynolds is an Associate Professor at the University of Arizona College of Public Health. She holds a Master of Science Degree in public health (MSPH) from the University of South Florida and a doctorate in microbiology from the University of Arizona. Reynolds is WC&P’s Public Health Editor and a former member of the Technical Review Committee. She can be reached via email at reynolds@u.arizona.edu

Source: Water Conditioning and Purification Magazine.

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This Week’s Top Water News

Hawaii is expected to ban the popular tourist attractions that allow tourists to swim with dolphins.

A single shower using products made with plastic microbeads can result in 100,000 plastic particles entering the ocean. Goverments are being urged by environmentalists to ban plastic microbeads.

Sacred water on a Crow reservation in Montana is contaminated with high levels of uranium.

Researchers found that Gwynns Falls on the western side of  Baltimore is contaminated not only with raw sewage from leakage from the city’s sewer system but also significant levels of pharmaceuticals and illegal drugs.

An estimated 4,500 people in Havelock North (New Zealand) got sick with a gastrointestinal infection linked to campylobacter bacteria in the town’s water supply. An intrusion of fecal bacteria from livestock was suspected.

Hydgrogen sulfide levels in the Salton Sea continue to rise and the stink rising from the water is definitely on the increase.

The market for activated alumina, used for a variety of purposes in water treatment, including fluoride removal, is expected to reach $1,110 million by 2024.

A German public broadcasting station drew a barrage of criticism for reporting that Israel does not provide adequate water for the Palestinians.

A Canadian animal rights activist was arrested for giving water to slaughterhouse-bound pigs, and in Georgia a man was sentenced to 40 years in prison for pouring boiling water on a sleeping gay couple.

The NCAA Playing Rules Oversight Committee for water polo announced that stricter rules for misconduct will be in effect during the 2016-17 season.

On Aug. 26, 2016,  President Barack Obama announced the establishment of the largest ocean sanctuary on the planet. His action quadrupled the size of an existing refuge,  Hawaii’s Papahānaumokuākea Marine National Monument, created originally by President George W. Bush.

It is estimated that the water lost from leaking pipes exceeds seven billion gallons every day.

America’s Water Supply: The Corrosion of a Proud Tradition

U.S. communities suffer from about a quarter of a million water main breaks every year, mostly due to aging pipe

By Robert Glennon,  Aug. 2016.

A common sight in American cities. 

The debacle in Flint, Michigan was a betrayal of the public trust at every level of government. The horror of people drinking poisoned water is a microcosm of the sad deterioration of one of America’s greatest accomplishments: the creation of infrastructure to provide virtually universal access to clean water and wastewater treatment.

Across America, water and sewer plants, pipes, and valves are reaching or beyond the end of their useful lives. By failing to invest in maintaining the city’s drinking water infrastructure, Flint officials acted no differently than those in thousands of other communities – high- and low-income – who are neglecting the promise of government that all residents have the right to clean water.

In early twentieth century America, it was not safe to drink water from public taps. Cities routinely dumped raw sewage into nearby rivers, thus causing their downstream neighbors to suffer epidemics of waterborne diseases, such as cholera, dysentery, and typhoid. This practice finally ended after Congress passed the 1972 Clean Water Act, which underwrote the costs of municipal water treatment plants.

In the 1980s, Congress’s taste for funding the construction costs waned, and it created a revolving funds program, which provided low-interest loans to states and cities. That worked pretty well for a while. But, in subsequent decades, spending on water and wastewater infrastructure plummeted.  In the aftermath of the Great Recession, the American Recovery and Reinvestment Act of 2009 (Mr. Obama’s stimulus program) devoted only $6 billion out of $800 billion to our water systems. That’s not chump change but the scale of the problem is immense.

Our water infrastructure consists of approximately 54,000 drinking water systems, with more than 700,000 miles of pipes, and 17,000 wastewater treatment plants, with an additional 800,000 miles of pipes. A 2012 report of the American Water Works Association concluded that more than a million miles of these pipes need repair or replacement. That’s why communities across the nation suffer 240,000 water main breaks per year. The major cause of pipe failure is age.

The negative health and environmental effects of decaying water infrastructure, as in Flint, stretch far beyond lead poisoning. Corroding pipes may leach cadmium, copper and iron into drinking water. Leaking pipes compromise water pressure and may induce contaminants to enter the drinking water system. Deteriorating sewer pipes leach fecal matter into aquifers and rivers. Aging treatment plants may fail to remove bacteria, parasites, and endocrine-disrupting compounds. No one knows which communities will be the next Flint; but these potential risks will turn into health crises without aggressive steps to modernize the infrastructure.

Episodes such as Flint undermine the public’s confidence in the safety of their drinking water. As Americans begin to doubt the quality of municipal water, some will opt out, choosing to install expensive water filtration systems in their homes. When more affluent citizens no longer have a stake in maintaining high-quality municipal water, that leaves behind people of more modest means – people without the same influence on elected officials.

The water lost from leaking pipes exceeds seven billion gallons a day. No one has estimated how much cities spent treating this water to drinking water quality. Whatever the amount, it’s lost revenue, never to be repaid by customers. Upgrading our water infrastructure will require substantial capital. Estimates range from $682 billion by the EPA to more than $1 trillion by the American Water Works Association.

Solving this problem presents a daunting challenge that asks us who we are as a people. Do we care enough about our communities to make water infrastructure a priority? It won’t be an easy road:  No politician wants to run for reelection on a campaign of having overhauled the sewer system.  Yet, recent polls suggest that Americans want public officials to act and are ready to pay more for a secure supply of safe water.

Public officials—local, state, and federal—must devote substantial funds to modernize water and wastewater systems. Congress, in particular, should initiate a new Clean Water Act program to underwrite the costs of municipal water treatment plants and should vastly increase funding for loans to states and cities. State and local governments should issue ultra-long-term government bonds (perhaps for 50 years as European governments have recently done), so that modernization can begin now but the repayment costs spread out over longer periods. Finally, to generate needed funds, one sensible option is to enter public-private partnerships that tap into the capital markets for construction costs in exchange for a system of rates and fees to reimburse the lenders.

Our water and wastewater systems have set the benchmark for the world. We should feel pride in this stunning achievement.  Now, we need to summon the resolve to fix the problem and maintain the proud tradition of providing safe, clean water and wastewater treatment to virtually every American.

Robert Glennon is a Regents’ Professor at the University of Arizona and author of Unquenchable: America’s Water Crisis and What To Do About It.

Article Source: Scientific American.

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This Week in Water

The bare bones water news of the week, link free, commercial free.

In Rio, Olympic water event athletes were warned by officials against putting their heads under the water.  Canoe sprint, marathon swimming, rowing, sailing, and triathlon all take place in open water that is dangerously polluted. Two canoers from Serbia took a spill in the dirty water on the first day of competition.

California Delta Tunnel officials have decided that they put their billion $ straws in the wrong place.

In the UK, unautorized animal medicinal products were seized from World of Water vets.

Studies show that the decline in salmon began with and resulted from the development of water power in the Middle Ages.

Cornell University will be required to cut back its water use by 30% because the city of Ithaca, NY is running out of water.

New Hampshire officials have banned outdoor water use in 50 towns and cities because of drought conditions.

Researchers at the University of Ghent in Belgium have developed a solar-powered machine that converts urine to drinkable water  that is then used to brew beer.

Although Californians used 21.5% less water in June than they did in 2013, usage was up 6% from 2015 due to relaxed regulations.

After restricting oil and natural gas operations in certain hotspots, Oklahoma has an average of two earthquakes a day, compared with about six a day last summer. Kansas has increased restrictions on natural gas operations and is getting about a quarter of the quakes it once did.

The EPA estimates that some 775 municipalities around the country have antiquated combined sewage and stormwater overflow systems. When it rains heavily or snow melts, the systems are overwhelmed and dump untreated sewage and stormwater into rivers and lakes.  One New York city dumps thousands of gallons of untreated sewer discharge into the Hudson River as many as 30 times per year.

An Oregon-based  company is using solar technology to reduce Salmonella, E. coli and Listeria contamination in agricultural runoff.

The water supply at Dog Ridge, Texas was cited for multiple drinking water violations.

It was reported that 60 percent of coral reefs in the Maldives have fallen victim to bleaching because of rising sea temperatures.

The Silent Highwayman

(Click picture for a larger view.)

Published by Punch magazine in July 1858, “The Silent Highwayman” serves as a grim reminder of the rank state of the River Thames, which in mid-nineteenth century London doubled as open sewer and drinking water source.

“The Silent Highwayman” serves as a reminder of a memorable time in London known as The Great Stink of 1858.  The great stink occured as the result of an intense heat wave and a spectacularly inadequate waste disposal system that created a stench of human excrement so noxious that it was said to be unbearable.

It was a time of typhoid and cholera. Londoners distrusted the drinking water, which came from the same river that received the city’s raw sewage. One cleric observed: “He who drinks a tumbler of London water has literally in his stomach more animated beings than there are men, women and children on the face of the globe.”

The Great Stink episode prompted action and London began work on a monumental sewage disposal system known as the Crossness Pumping Station. Opened on April 4, 1865, during a lavish ceremony attended by British royalty and the top celebrities of London society,  the new facility featured four mighty steam engines that pumped the city’s sewage into a 27 million gallon reservoir where it sat covered until high tide at which point it was released into the Thames and carried out to sea. While this approach only exacerbated pollution levels downstream, it certainly proved effective in curing London of the unholy stink that plagued the city for a great part of the 19th century. Improved over the years, the Crossness Pumping station (now a museum) operated for around a hundred years. The original four mighty steam engines were not retired until 1956.

The Crossness Pumping Station is now an impressive museum in London. The four great steam engines, which were given names of royal family members, are on display.

Those who complain today of stricter regulation of water and air quality and increasing water treatment costs should remember that things were once a lot worse. Modern waste water treatment plants not only protect water supplies but are increasingly used to recycle waste water for reuse as potable water. So, quit bitching about increasing water rates. Pay up and be thankful you don’t have to live with The Great Stink and fear of cholera.

More information from the Mother Nature Network.

FilterSorb SP3 Advanced Salt-Free Scale Prevention Units

FilterSorb NAC (“Nuclear Assisted Crystallization”) technology is the leading rival of OneFlow TAC (“Template Assisted Crystallization”). The two competing technologies both have many strong points and we now offer both. Either FilterSorb, shown  below, or OneFlow, on our main website,  will do an excellent job of salt-free scale prevention.

FilterSorb is NSF 61 certified. It adds no chemicals to the water, needs no regeneration, needs no electricity or drain connection. It is trouble free, and the expected media life is three to five years. FilterSorb not only prevents formation of hard water scaling, it also helps to reduce previously formed scale. FilterSorb does not add sodium to water and it does not remove calcium and magnesium from drinking water. It does not alter pH or total dissolved solids of the treated water.

Here’s how one author explains the NAC process:

The Filtersorb SP3 acts as a catalyst by accelerating the transformation of the calcium and magnesium minerals into harmless “Nano” particles. When the inlet water goes into the water conditioner tank, the up flow pulls the water through the fluidized Filtersorb SP3 media which then acts as a catalyst and pulls the hardness minerals of calcium and magnesium out of the solution and then transforms these minerals into inactive Nano crystal particles. Because the hardness minerals have been transformed into Nano particles, these Nanoscopic particles make their way through plumbing systems without attaching on to pipes, fixtures, valves, or heating elements. Filtersorb SP3 is also a maintenance free system that does not require cost for salt, costs for water or for regeneration material.

Because of the simple in/out design without electrical or drain connection, FilterSorb units are especially easy to install. We highly recommend installing a sediment filter in front of the FilterSorb system to guard against intrusion of particulate.

Basic FilterSorb Unit with Optional Bypass (red-handled valves). In this upflow system, water flows upward from the bottom of the tank through the treatment media.  No backwashing is required, so, unlike conventional water softeners, the FilterSorb system does not require water for backwash, rinse, or brine circulation. No connection to drain is needed.

FilterSorb units are made with only a few liters of high potency media in a large tank, so there is virtually no pressure drop. The larger-than-necessary tank enhances performance by allowing the FilterSorb media to fluidize freely and have more contact time with the water.

FilterSorb can be used in water temperatures from 38 to 140 F and up to a hardness of 75 grains, although sizing for the residential units offered on this page is for water up to 25 grains hardness. If your hardness exceeds 25 grains, we can help with sizing the unit.

FilterSorb can tolerate high salinity (up to >2000 grains). Acceptable pH range is 6.5 to 9.5. Maximum iron content recommended is 0.2 ppm, and maximum manganese 0.5 ppm. Up to 1.3 ppm copper can be tolerated, but the medium requires zero oil, phosphates, and hydrogen sulfide. Although FilterSorb is fairly chlorine tolerant, the life of the media will be prolonged if a carbon filter is installed in front of the scale prevention unit in city water or chlorinated well water applications.

Standard FilterSorb Treatment Unit with the optional bypass. No electricity or salt are needed. The standard Filtersorb unit is built in a Vortech mineral tank with an upflow Clack head.

Pure Water Products FilterSorb Residential Units

Free Shipping to Lower 48 US Addresses.

Rebedding Softeners and Filters

In general, putting new media into a water softener or tank-style filter is like screwing the lid off of a bottle, dumping out the contents, then refilling the bottle. What complicates the procedure is largely that it is a very big bottle and it is often located in an inconvenient place. It doesn’t have to be a hard job, but it can be a messy job.  Here are suggested steps:

• Start by disconnecting from your house plumbing. If you have a bypass valve on the filter or softener, put it in bypass. If not, turn off the water source. Disconnect the control valve from house plumbing. With Fleck controls, simply remove the two clips that hold the bypass (or yoke) to the control valve. The drain line will also have to be disconnected from the control valve.
• Move the filter/softener away from the plumbing connection so that you have room to work, then screw the control valve off the tank (like screwing the lid off of a bottle). It screws out counter-clockwise. You should not need a wrench, but this is often a two-person job, with one person holding the tank in place while the other unscrews the control valve.
• Next, you’re going to get the filter media out of the tank. This may be easy or very difficult, depending on where the filter is located, how large it is, and the condition of the media bed. If the filter is small enough and relatively clean, you can simply move it to a convenient location–near a drain, or outdoors–turn it over and dump out the contents. However, if it’s a heavy tank or the media is laden with iron or dirt, you’ll have to improvise. Sometimes with very dirty iron filters it’s more practical to replace the tank than empty it. Some tricks that can make this job easier include siphoning out some water to lighten the tank so it can be moved outdoors or to a floor drain or using a shop vac to suck out the water and the media. Except in exceptional cases, like arsenic filters, the old media in the tank is not regarded as a hazardous material, so you can dump it on the lawn or dispose of it as you see fit. If you have a conventional filter tank, the center tube (dip tube or riser) can be removed to make it easier to dump out the media; with a Vortech tank, the riser is attached to the bottom of the tank, so it stays in place and you’ll have to work around it. If  you’re outdoors and can get the tank propped mouth-down at a 45 degree angle, you can insert a running garden hose into the tank and in most case wash the media out easily.

Using a media funnel. Note that the dip tube is covered to keep media from getting inside the tube (and subsequently into the home’s service lines).

• When the tank is empty, rebed by pouring in media using the same procedure you would use for filling a new filter. Before you pour in gravel or media, be sure you cover the top of the riser tube with tape or a small plastic bag to keep media from entering the riser tube. If it’s a standard tank, be sure the riser is in place in the bottom of the tank, pour in gravel, if needed, then pour in the filter media. With standard tanks, you’ll need  gravel underbedding for filter media; with residential-sized softeners, gravel is usually optional.  With Vortech tanks, except in rare cases, no gravel is needed for filters or softeners.  Since dry filter media often puts off dust, it is recommended that you wear a face mask while filling the tank to avoid breathing in dust. Filling the tank is most easily done by two people. Using a media funnel greatly facilitates the task. Without a funnel, you may have to scoop it in.
• When the tank is full (“full,” in most cases, means about 1/2 to 2/3 deep in the tank), replace the control valve.  It is important to lubricate the o ring that makes the seal between the top of the tank and control valves with silicone. Also, lube the o rings inside the bottom hole of the control valve so that the riser can slide in easily and make a good seal. Be sure to clean media dust out of the threads on the tank before screwing on the valve to prevent damaging the threads. Screw the head on snugly. No tool is needed.
• When the control valve is back on the tank, reinstall to your plumbing, then follow the startup procedure you would use for a new filter or softener.
• Check for leaks.

Roundup

Glyphosate, known better as Roundup and sold under several other brand names as well, a product of Monsanto, has been around since 1974.  It is a potent and popular herbicide, registered for use in 130 countries. The world consumes more than 720,000 metric tons annually, so there is plenty to get into water. Glyphosate was detected in 36% of stream samples from 9 Midwestern US states as far back as 2002.

Although Roundup has always been viewed with suspicion, there had been little evidence that it poses a cancer risk to humans. Recent studies, however,  have shown mixed results. Currently, the EPA sets its MCL at 700 parts per billion. The World Health Organization has for years insisted that regulatory guidelines are not necessary because Glyphosate poses  low risk in drinking water.

Despite such assurances, most prefer not drinking Roundup.  There are many options for getting rid of it. These include chlorination, ozonation, nanofiltration, reverse osmosis, and filtration with granular activated carbon.

Reference: Water Technology magazine, July, 2016.

Gazette Afternote:  In August of 2018, a California jury found Monsanto liable in a lawsuit filed by a man who alleged the company’s glyphosate-based weedkillers, including Roundup, caused his cancer and ordered the company to pay $289 million in damages.This case has certainly cast doubts on the “low risk” assessment.  As early as 2015, the World Health Organization’s cancer arm classified glyphosate as “probably carcinogenic to humans.” 

Gazette Afternote 2: In June 2020, Roundup maker Bayer AB announced a blockbuster $10 billion dollar settlement to resolve cancer lawsuits connected to its weedkiller Roundup. This after Bayer faced tens of thousands of claims linking the active ingredient in RoundUp– glyphosate– to increased risk of developing Non Hodgkins Lymphoma.

The lesson here, of course, is that experts, including the World Health Organization, don’t always get it right. It is always best to err on the side of caution. Having a good drinking water system in the home serves as protection against mistakes by the experts.

The Meaning of “Temporary” and “Permanent” Hardness

Gazette Water Wizard Pure Water Annie Explains Why You Have to Watch Out for Temporary Hardness

What we call hardness in water–the property that causes hard scale to form on appliances and inside pipes and water heaters, spots on dishes, and soap scum–is caused by the presence of calcium and/or magnesium ions in the water. The more calcium and magnesium, the harder the water. The sum of the concentrated calcium and magnesium is often called “total hardness.”

All hardness, however, is not created equal. The hardness that gives you trouble in the home is what is called “temporary” hardness, as opposed to “permanent” hardness. That’s because temporary hardness, also called carbonate or bicarbonate hardness,  breaks down when it’s heated and forms hard scale. Permanent hardness, on the other hand, does not break down when heated and does not cause problems.

The test, then, for whether hardness is “permanent” or “temporary” is how it behaves when heated. Needless to say, in the home, hot water heaters and any appliances that use hot water are very vulnerable to the effects of temporary hardness.

In general terms, temporary hardness is the predominant form. Most water hardness is either all temporary or a mixture of temporary and permanent.

If you look at a water analysis, the way to determine the type of hardness is to compare the total hardness with the total alkalinity of the sample. Most water tests report both hardness and alkalinity “as CaCO3.”  Reporting “as if it were Calcium Carbonate” is simply a way of putting the items in a common frame of reference so they can be compared, the way we find a “common denominator” when we add fractions.

If the total alkalinity of the water is greater than the total hardness, then all the hardness in the water is temporary.  However, if the total alkalinity is less than the total hardness, both permanent and temporary hardness are present and the the amount of temporary hardness is equal to the alkalinity.

Here are examples:

Hardness — 150 ppm.

Alkalinity — 250 ppm.

Result: Temporary hardness=150 ppm.  (Alkalinity exceeds hardness, so all hardness is temporary.)

Hardness — 150 ppm.

Alkalinity — 100 ppm.

Result — Temporary hardness= 100 ppm.  Permanent hardess = 50 ppm.  (When hardness exceeds alkalinity, temporary hardness is equal to alkalinity and permanent hardess equals total hardness less alkalinity.)

What does all this matter?  Not much for residential water users, since most hardness is reported as “total hardness” and both types are treated with a water softener.  It might matter, though, if you were manager of a municipal water system, since temporary hardness can be reduced by a process called “lime softening” that isn’t used for residential treatment.