Common Water Disinfecting Method May Result In Toxic Byproducts, Study Finds

Toxic and carcinogenic compounds are produced when phenols in drinking water mix with chlorine, the most common chemical used to disinfect drinking water in the U.S.

Chlorine, the most common chemical used to disinfect drinking water in the United States, creates previously unidentified toxic byproducts in the very water its meant to disinfect, according to a new study from researchers at Johns Hopkins and the University of California, Berkeley, as well as in Switzerland.

The researchers’ findings were recently published in the journal Environmental Science & Technology

“There’s no doubt that chlorine is beneficial; chlorination has saved millions of lives worldwide from diseases such as typhoid and cholera since its arrival in the early 20th century,” says Carsten Prasse, an assistant professor of Environmental Health and Engineering at Johns Hopkins and the paper’s lead author. “But that process of killing potentially fatal bacteria and viruses comes with unintended consequences. The discovery of these previously unknown, highly toxic byproducts raises the question of how much chlorination is really necessary.”

Phenols, chemical compounds that occur naturally in the environment and are abundant in personal care products and pharmaceuticals, are also commonly found in drinking water. When these phenols mix with chlorine, the process creates a large number of byproducts. Current analytical chemistry methods, however, are unable to detect and identify all of these byproducts, some which may be harmful and can cause long-term health consequences, says Prasse.

For the study, Prasse and his collaborators added N-α-acetyl-lysine, which is almost identical to the amino acid lysine that makes up many proteins in our bodies, to detect reactive electrophiles, harmful compounds which have been linked to a variety of diseases. The technique of identifying compounds based on their reaction with biomolecules like DNA and proteins is commonly used in the field of toxicology.

The researchers first chlorinated water using commercial methods: they added excess chlorine, which ensures sufficient disinfection but also eliminates harmless smell and taste compounds that consumers often complain about. Then the team added the aforementioned amino acid, let the water incubate for one day, and used mass spectrometry, a method of analyzing chemicals, to detect the electrophiles that reacted with the amino acid.

Their experiment found the compounds 2-butene-1,4-dial, or BDA, and chloro-2-butene-1,4-dial, or BDA with chlorine attached. BDA is a very toxic compound and a known carcinogen that, until this study, scientists had not detected in chlorinated water before, says Prasse.

Source: Johns Hopkins University. Reprinted from Watertech Online.

Which sediment filter cartridge is best? Wound string, melt-blown, or pleated?

Water filter cartridges whose function is to trap suspended particles come in three distinct styles.  Mr. Robert LeConche, President of Shelco, one of the largest makers of sediment filtration products, describes them like this:

Wound Filters. Wound filters are versatile all-purpose filters that exhibit rather high dirt-holding capacities. They are relatively low cost, depending on the materials of construction, and work well in most applications. This style of filtration offers great compatibilities because of a wide range of raw materials available for production. Its distinct diamond patterns create fluid channeling from the outer diameter to its center core making it a true depth filter. One caution is that low-quality wound filters used under high differential pressures have a tendency to “unload” or release sediment that was previously filtered out of the solutions.

Melt blown or Spun. Melt-blown or poly spun filters are almost always made of FDA-grade materials for use in potable water and food and beverage applications. There are two levels of product efficiencies, Nominal and Absolute rated. Nominally rated cartridges should offer efficiencies ranging from 70% to 80%. Absolute or High Efficiency Melt Blown Cartridges will offer efficiencies in the range of 90% to 99%. Melt-blown filters are usually a lower cost option to wounds or pleated cartridges (although they may require more frequent cartridge changes).

Pleated. Pleated filters offer higher flow rates with lower clean differential pressures and extended filter life than most cartridge filters. They are almost always made of FDA grade materials for use in potable water and food and beverage applications. Pleated filters can be used alone or as final stage filtration in multi-stage filter systems. Although pleated filters typically are more expensive than other filters, they have a longer filter life and some can be clean and reused (when appropriate). Pleated cartridges also offer nominally rated and  bsolute rated alternatives.

As to which is “best,” our answer is usually that it depends on the individual case. Some customers prefer one, others swear by another.  Whichever works best in your situation is the best.

Wound string and melt-blown cartridges are called “depth” cartridges because they can trap and hold particles beneath the surface, while pleated filters trap and hold sediment on the surface only. However, pleated filters have much more surface area than the other styles because of the unique accordion shape.  Although pleated cartridges usually cost more, they can be washed and reused in most cases. The rule of thumb is that pleated cartridges of 5-microns or more can be reused; tighter than 5 microns, reuse usually is impossible. Because of their great surface area, pleated cartridges can often support a higher service flow rate as well.

A well-used wound string filter. Note the diamond patterns mentioned by Mr. LeConche.

Residential Chlorine Cartridge Filters

RFC20-BB

Cartridge-style whole house filters for city water have many advantages.  They install easily without need for a drain connection and electricity, they are compact and can be wall mounted, they require little upkeep,  and they are very effective.

Below are specially priced cartridge-style whole house  filters designed for city homes whose water supplier uses chlorine (rather than chloramine).  The chloramine version of the same filters are also available. The chlorine filters on this page  use the exceptional Pentek Radial Flow Carbon Filter.  This unique cartridge offers long life, excellent taste/odor performance, and almost no pressure loss.  The radial flow granular style of the RFC20BB restricts flow less than 1 psi at 4 gallons per minute, a fraction of the pressure drop from comparable carbon block filters.  The filter uses powdered carbon that is held in place by a uniquely designed cartridge that eliminates the need for the plastic binders used in carbon block filters.

These units cost a bit more than our standard carbon block whole house units, but their free-flowing performance makes them worth the added expense.

The package systems we’ve put together include a filter wrench, housings, extra O Rings,  brackets, and cartridges.  All housings have 1″ ports (3/4″ or 1.5″ available upon request).  All housings, both 20″ and 10″,  are tough, reliable Pentek “Big Blue.”  All housing packages include mounting screws, heavy duty metal brackets, and one extra housing O Ring.

These systems are designed for parallel installation for larger homes to assure minimal pressure drop and optimal chenical/chlorine performance. See the reference pages listed below for installation pictures. Note that all carbon filters are 20″ and all sediment filters are 10″. The housing caps and brackets are identical for easy installation.

Whole house cartridge filters offer many advantages as compared with tank-style filters.  They install easily (no drain connection and no electricity needed). They are reliable, simple, easily serviced units with a very long lifespan. As compared with backwashing filters, these compact whole house carbon units save hundreds of gallons of water per year because no backwash is needed.

The RFC20 is a NSF-42 certified cartridge with a manufacturer’s rating for 70,000 gallons of chlorine removal @ 4 gpm. PSI drop at 4 gpm is only 0.9 psi. (The cartridge will support a higher service flow. See sizing notes below.)

 Basic 20″ Big Blue Housing

Multi-filter installation. Water passes through sediment filter on the left, then splits to pass through two carbon filters.  (The sediment filter is a 10″ cartridge and the two carbon filters are 20″.)

See also:

High Performance Cartridge-Style Chloramine Filters.  (This is the chloramine version of the products on this page. Chloramine reduction requires specialty carbon and in general needs a slower flow rate or greater filter capacity than chlorine reduction.)

Compact Whole House Filters.

More Multi-Filter Installation Pictures.

General Installation Instructions for Compact Whole House Filters.

U.S. drinking water widely contaminated with ‘forever chemicals’: environment watchdog

By Timothy Gardner

The contamination of U.S. drinking water with man-made “forever chemicals” is far worse than previously estimated with some of the highest levels found in Miami, Philadelphia and New Orleans, said a report on Wednesday by an environmental watchdog group.

The chemicals, resistant to breaking down in the environment, are known as perfluoroalkyl substances, or PFAS. Some have been linked to cancers, liver damage, low birth weight and other health problems.

The findings  by the Environmental Working Group (EWG) show the group’s previous estimate in 2018, based on unpublished U.S. Environmental Protection Agency (EPA) data, that 110 million Americans may be contaminated with PFAS, could be far too low.

“It’s nearly impossible to avoid contaminated drinking water from these chemicals,” said David Andrews, a senior scientist at EWG and co-author of the report.

The chemicals were used in products like Teflon and Scotchguard and in firefighting foam. Some are used in a variety of other products and industrial processes, and their replacements also pose risks.

Of tap water samples taken by EWG from 44 sites in 31 states and Washington D.C., only one location, Meridian, Mississippi, which relies on 700 foot (215 m) deep wells, had no detectable PFAS. Only Seattle and Tuscaloosa, Alabama had levels below 1 part per trillion (PPT), the limit EWG recommends.

In addition, EWG found that on average six to seven PFAS compounds were found at the tested sites, and the effects on health of the mixtures are little understood. “Everyone’s really exposed to a toxic soup of these PFAS chemicals,” Andrews said.

In 34 places where EWG’s tests found PFAS, contamination had not been publicly reported by the EPA or state environmental agencies.

The EPA has known since at least 2001 about the problem of PFAS in drinking water but has so far failed to set an enforceable, nationwide legal limit. The EPA said early last year it would begin the process to set limits on two of the chemicals, PFOA and PFOS.

The EPA said it has helped states and communities address PFAS and that it is working to put limits on the two main chemicals but did not give a timeline.

In 2018 a draft report from an office of the U.S. Department of Health and Human Services said the risk level for exposure to the chemicals should be up to 10 times lower than the 70 PPT threshold the EPA recommends. The White House and the EPA had tried to stop the report from being published.

Source: Reuters report via Yahoo News.

Pure Water Gazette Fair Use Statement

TAC or Water Softener: Pros and Cons

With the growing popularity of alternatives to conventional water softeners, most notably Template Assisted Crystallization (TAC) systems, residential customers are finding it more difficult to choose a home treatment system for hardness.

Below here are some issues that come up and our comments on them, based both on our direct experience with the products themselves and on discussions we’ve had with customers who use them, In each case, we’re comparing a standard TAC unit to a standard conventional water softener.

Adds salt to water:  The softener works by exchanging salt for calcium and magnesium, so, yes, it adds salt.  TAC does not use salt.

Removes hardness.  Calcium and magnesium are the minerals that cause water to be hard. A softener removes them.  TAC “conditions” them so that they are less offensive; it does not remove hardness, so it really should not be called a softener. There is currently no  simple way (like a hardness test) to quantify the effect that TAC units have on hardness.

Gives the water a feeling of slickness.  Softener, yes; TAC, no. The slick feel, of course, is a positive effect for some users, a negative to others.  And, unfortunately there is currently no test for “slickness.”

Makes soap lather better, thus saving soap.  Softener, yes; TAC, perhaps a little.

Makes plumbing and appliances last longer.  Yes in both cases.

Initial cost comparison. Softeners vary in price, a lot, depending on style and manufacturer.  In general, TAC units cost more than good quality softeners but less than high-end softeners.

Upkeep. Operating Cost.  If the user’s labor is considered, or if the user pays someone to keep the softener cleaned and full of salt, the softener costs more. The single “upkeep” cost for TAC units is media replacement, which is expensive, but it only happens about every third year.  TAC uses no salt, no water for regeneration, no electricity, and has no moving parts that break. TAC units are so simple that most users can do the occasional media replacement themselves.

Environmental impact.  TAC uses no water for regeneration and adds nothing to the waste stream. Softeners use considerable amounts of water for regeneration and add salt to the city’s waste stream or the septic tank. Why is this a big deal? Because city water departments are hard-pressed to dispose of the waste water, which usually can’t be used for irrigation because of the salt content. Softeners, by the way, can be regenerated with potassium chloride rather than sodium chloride, which is regarded as more environmentally friendly but which is considerably more expensive than plain old softener salt.

Health issues.  Although we believe that the amount of salt added to drinking water by a softener probably has no negative health impact unless you drink outrageous amounts of it, not everyone would agree. The salt can be removed from softened water by an undersink reverse osmosis unit. RO removes salt handily.  TAC adds nothing objectionable to drinking water–at least nothing we know about yet. Softeners add salt and remove calcium and magnesium; TAC units neither add nor remove minerals.

Aesthetics. Some people (usually people who grew up with softened water) like the “slick” feel and the illusion that soap can’t be washed off the skin. Some people (usually people who grew up bathing in hard water) don’t.  TAC units do not affect the water aesthetically. The water feels, smells, tastes, and looks the same as untreated water.

Installation.  The TAC unit is easier to install. The softener needs electricity and a drain connection.  TAC needs neither. The softener has a control valve to program and a startup procedure to follow; TAC units require no programming or setup.

Pre-treatment — A sediment filter is essential in front of the TAC unit and is usually a good idea in front of a softener. In general, softeners are tougher and require less protection. Softeners actually remove small amounts of iron and manganese, but TAC units must be protected  from them by pre-treatment. Likewise, TAC units are very sensitive to copper and have to be protected from new copper piping by remaining in by-pass mode until new copper piping is seasoned. Both softeners and TAC units last longer with pre-treatment for chlorine or chloramine  in city water, but this is not essential.

 The conventional softener in the picture consists of the tall resin tank, the control valve on top, and the brine tank where salt to regenerate the resin is stored.  TAC units have only the tall tank and the top valve does not require electricity. No brine tank is needed. 

Dark Waters: Water Contaminants in the Movies

A highly promoted movie called Dark Waters came out in late November 2019. It stars Mark Ruffalo and tells the story of Cincinnati lawyer Rob Bilott and his dozen-year battle against the centuries-old American chemical company, DuPont.  From an effort to gain justice for a single client whose livestock were poisoned by Dupont’s chemical PFOA, Bilott’s efforts resulted in large class-action settlements for hundreds of injured parties. Ruffalo, who is known as an environmental activist as well as an actor, produced the film as well as starring in it. Other top actors featured are Anne Hathaway and Tim Robbins.

Dark Waters joins other important movies that brought significant water contaminants to public attention. The stories of all are similar. They feature an individual who takes on a powerful company that seems to be above the law.  The best known of these is Erin Brockovich, starring Julia Roberts, which tells the story of the hexavalent chromium (aka chromium-6) poisoning of the water in Hinkley, CA by Pacific Gas and Electric. A lesser known but equally compelling story is that of the TCE poisoning of the wells that supplied Woburn, MA by the W.R. Grace company. The incident inspired an outstanding book by Jonathan Harr that in turn inspired the 1998 movie A Civil Action, starring John Travolta and Robert Duvall. (The book was better than the movie, but both deserve your attention.)

Why Don’t Tiny EOT (End of Tap) Filters Work As Well As Standard Filters? Well, Because They Are Tiny

Most of the bad publicity (“filters don’t work”) that resulted from poor performance on tests done on lead filters supplied to homeowners in Flint and Newark ignored the fact that the filters provided were novelty-sized units meant for off-the-shelf purchase. They could not be expected to “work” as well as full-sized filters actually designed for long-term  use in homes.

Here is sizing information from the manufacturer of MetSorb®, a heavy metal removal medium that is added to carbon block filters to give them lead-removal capacity.

A nominal 10 – inch carbon block, standard for most countertop and undercounter applications, will provide more overall volume and more functional media than the 2 to 2-1/2 inch blocks typically used in end-of-tap (EOT) applications. For example, a nominal 10 – inch carbon block can easily perform for 1000 gallons or more of contaminant reduction, while the smaller EOT blocks are rated at several hundred gallons.

The larger block design also gives longer contact times (EBCT or Empty Bed Contact Time) for better contaminant reduction. For example, a nominal 10 – inch block will provide an EBCT of 10 -15 seconds, while a typical 21/2 inch EOT block gives only 3 seconds EBCT. Devices designed for slower flow rates, e.g., 0.5 gpm (gallons per minute) versus 1.0 gpm will provide longer contact times and better percentage contaminant reduction.

This 10″ carbon block fits standard sized countertop and undersink filters and provides 2500 gallons of lead-free water at 0.75 gallons per minute.   

President Trump Addresses Water Conservation

At a December 16, 2019 meeting of small business leaders at the White House, President Donald Trump talked at length about water and energy conservation, saying the Environmental Protection Agency is looking into restrictions in part because people are flushing their toilets 10 to 15 times instead of once and are therefore using more water.

“We have a situation where we’re looking very strongly at sinks and showers and other elements of bathrooms, where you turn the faucet on in areas where there’s tremendous amounts of water, where it all flows out to sea because you could never handle it all, and you don’t get any water,” he said.

“They take a shower and water comes dripping out, very quietly dripping out. People are flushing toilets 10 times, 15 times, as opposed to once; they end up using more water. So EPA is looking very strongly at that, at my suggestion.

“You go into a new building, new house, a new home, and they have standards where [you] don’t get water, and you can’t wash your hands practically; there’s so little water,” he added. “And the end result is that you leave the faucet on, and it takes you much longer to wash your hands, and you end up using the same amount of water. So we’re looking very seriously at opening up the standard, and there may be some areas where we go the other route, desert areas, but for the most part, you have states where they have so much water where it comes down — it’s called rain — that they don’t know what to do with it.”

Sulfur & Groundwater

Gazette’s Introductory Note: The piece below is adapted from an information sheet provided by the non-profit Water Systems Council.  It addresses one of the more confusing topics in water treatment, the “sulfur” or rotten egg smell in well water. Bad smelling water is variously attributed to sulfur, sulfate, or hydrogen sulfide. This document seeks to shed some light on the origin and treatment of bad smelling water. 

What is Sulfur?

Two forms of sulfur are commonly found in drinking water: hydrogen sulfide and sulfate-reducing bacteria. Both forms are nuisances that usually do not pose a health risk at the concentrations found in domestic wells.

Hydrogen sulfide gas occurs naturally in some ground water that contains decaying organic matter, such as wetlands, marshes, swamps, river beds. It may be found in deep or shallow wells. Hydrogen sulfide is often present in wells drilled in shale or sandstone, or near coal or peat deposits or oil fields.

Sulfate is a combination of sulfur and oxygen, and is part of naturally occurring minerals in some soil and rock. The mineral dissolves over time and is released into ground water. Sulfur odor is produced when a non-harmful sulfur-reducing bacteria digests a small amount of the sulfate mineral.

What are the health effects of Sulfur?

The EPA considers sulfur a secondary water contaminant, with no direct threat to human health. Sulfate gives water a bitter taste and can have a laxative effect that may lead to dehydration. Hydrogen sulfide gives water a “rotten egg” odor and taste, and can cause nausea.

Hydrogen sulfide is corrosive to metals such as iron, steel, copper and brass. It can tarnish silverware and discolor copper and brass utensils. Hydrogen sulfide can also cause yellow or black stains on kitchen and bathroom fixtures. Coffee, tea and other beverages made with water containing hydrogen sulfide may be discolored and the appearance and taste of cooked foods can be affected. High concentrations of dissolved hydrogen sulfide also can foul the resin bed of an ion exchange water softener.

How do I test for Sulfur?

Testing for hydrogen sulfide can be difficult because the gas escapes into the atmosphere so quickly. Onsite testing is the most accurate method for determining hydrogen sulfide concentration, especially if the odor is excessive. Hydrogen sulfide concentrations greater than 5 mg/L are more difficult to treat and could require special testing methods to assure accuracy.

Sulfate-reducing bacteria is rarely tested, however testing for sulfate ion (mineral) concentration is. The premise is: if a rotten egg odor is present and the sulfate ion concentration is excessive – greater than 150 mg/L – the odor is created by sulfate-reducing bacteria.

The EPA sets standards for secondary water contaminants based on taste, odor, color, corrosiveness, foaming and staining properties. Hydrogen sulfide is not regulated because any concentration high enough to pose a health hazard will also make the water too unpalatable to drink. The EPA’s secondary limit for sulfate in drinking water is 250 parts per million (ppm).

What are the treatments for Sulfur in drinking water?

Treatment options depend on the form (whether hydrogen sulfide or sulfate-reducing bacteria) and quantities of the “rotten egg odor-producing” contaminants. Hydrogen sulfide treatment is with chlorination or aeration followed by filtration. Often, treatment for hydrogen sulfide is the same as for iron and manganese, allowing the removal of all three contaminants in one process.

Most water heater anode rods contain some sulfate so, in the presence of sulfate-reducing bacteria, a rotten egg odor is created in the hot water only. If this occurs, the first course of action is to replace the anode rod with an aluminum-based rod which limits the sulfate and therefore stops the odor.

Sulfate-reducing bacteria is treated with continuous chlorination. Removing sulfate mineral is difficult and usually not feasible, so chlorination kills the bacteria instead. The chlorination process involves a chemical feed pump system that injects a chlorine solution into the inlet of a retention tank that must be installed in the house piping. The retention tank must hold enough water to provide a 20-minute time period for the chlorine to react with the bacteria. The capacity needed for the retention tank can be calculated by multiplying the well pump output times 20. A continuous chlorine residual of 1.0 mg/L is required at the outlet of the retention tank to assure the bacteria were destroyed. Since chlorine can be combined with natural organic matter, it’s always recommended that an activated carbon filter be installed after the retention tank to remove the chlorine.

Pure Water Gazette Fair Use Statement

 Testing for ORP with Potassium Permanganate

Editor’s Note: The instructions below, which we’ve modified a bit, were prepared by the original manufacturer of Filox-R iron removal media. The purpose is to provide a quick and easy way to determine if your water can be treated by standard manganese dioxide-based iron filter media like Filox without the use of additional oxidizers like chlorine, air, ozone, hydrogen peroxide or potassium permanganate. 

Oxidation Reduction Potential (ORP) can be the most important factor to take into consideration in certain waters. Highly reducing waters may cause premature exhaustion or even destruction of the Filox-R bed.

Precautions can be taken prior to installation that can prevent ORP problems. Use one of the screening tests and follow the instructions below if the subject water has reducing properties that will require additional oxidants. 

 The Simple Test

Mix 1.75 ounces (50 grams) water with 0.75 ounces (22 grams) of potassium permanganate crystals. Then take 2 drops of the mixture and stir into a fresh ¼ gallon (1 liter) sample of the subject water. Let the subject water stand for 15 minutes. If the pink color remains, Filox-R can be installed without additional oxidants. If the pink color disappears, additional oxidants will be needed for Filox-R to function properly.

The ORP Test with a Meter

Note: Must use a calibrated ORP meter. Any reading that is above a negative 170 millivolts indicates that Filox-R can be used effectively without additional oxidants. Any reading falling below a negative 170 millivolts indicates that additional oxidants will be required.

The amount of oxidant required for proper installation can be determined by measuring the amount of oxidant added to a specific volume of subject water until the solution remains pink or the meter reads at negative 170 millivolts or above. An extrapolation can then be made to determine the correct feed rate for the oxidant with respect to the subject water flow rate. Once installed, sample the solution after the injector and mixer and repeat the above test to confirm that the feed rate is correct.