Pure Water Occasional, October 7, 2020 |
Predicting the Future by Looking at the Past
The Department of Health and Human Services is working on an ambitious plan to detect virus outbreaks by extensive testing of wastewater. Wastewater tests can provide an "early warning system" for coronavirus. The agency's contract notice says that surveillance of wastewater for the virus can detect an increase in COVID-19 cases five to 11 days earlier than by standard clinical testing. CNBC.
A Pie that Keeps Shrinking
Lake Mead, America's largest reservoir, is "a pie that keeps shrinking." As levels go down, reduction is made automatically to Colorado River water that can be drawn by Arizona, Nevada, and Mexico. Arizona, for example, gets nearly 40% of its water from the Colorado River. The state will again see its water take reduced by 192,000 acre-feet next year, or 6.9% of its total allotment of 2.8 million acre-feet. (Each acre-foot is 325,851 gallons, enough water to cover a football field nearly 1 foot deep.) As Lake Mead shrinks, so shrinks the water available for Arizona. Full story from AZ Central.
Recent water pipe ruptures drove people from their homes and closed businesses in Brasilia in northeastern Brazil, at UCLA, and all around the world. As pipes age, spectacular flooding and water damage caused by breaking pipes becomes more common.
Plastic Infrastructure and Wildfires
When there is wildfire, water infrastructure that’s made of plastic is particularly at risk of contamination. If pipes and tanks lose pressure or get hot, chemicals can leach into the water supply. When water supplies are contaminated so that the water is not acceptable for household use after a wildfire, often the quickest way to restore the water supply is to run new plastic piping above ground. Ironically, this leaves the water supply much more vulnerable to damage by fires. NPR Report about fires in Santa Cruz County.
A US Dept. Of Agriculture program is paying Vermont farmers to reduce water pollution by reducing phosphorus runoff from their fields. Huron Daily Tribune.
"Recent studies suggest that, even at concentrations meeting current federal standards, Atrazine may be associated with birth defects, low birth weights and menstrual problems. Laboratory experiments suggest that when animals are exposed to brief doses of atrazine before birth, they may become more vulnerable to cancer later." (NY Times Article from 2012.) Nevertheless, the EPA just issued new guidelines that allow expanded use of Atrazine and two other popular herbicides. "On average, approximately 58% of field corn or 53.3 million acres are treated with 62.3 million pounds of atrazine per year." The EPA recently refused to ban the pesticide Chlorpyrifos, in spite of a 2018 court order to do so and mounting evidence that it is harmful especially to children. Relaxed regulation at the EPA has become standard practice, with consumer safety being consistently trumped by concern for the profits of corporate "farmers." See "Atrazine gets positive interim desision from the EPA."
Legionella in Schools Being Reopened
To protect against the spread of coronavirus, many school buildings have been unoccupied since March. Their bathrooms, cafeterias and sports facilities have gone unused. While low occupancy in schools is typical during summer breaks, many are open for summer school and other activities which keep water running through the pipes. Experts worry that water was left to stagnate in plumbing during lockdown, and that schools don’t have plans or effective guidance from health authorities for dealing with the effects of prolonged shutdowns. Schools in Ohio and Pennsylvania have found Legionnela bacteria in schools that were closed for long periods, and bacteria of all types are a danger in schools where water has been stagant in the pipes for long periods. New York Times.
"Nurdles are tiny pellets used for producing numerous plastic products. Nurdles are a growing pollution source in global waterways and along coastlines. While barely the size of a lentil and weighing only about 20 milligrams, more than 200,000 tons of nurdles are reportedly finding their way from cargo ships into the oceans each year.
EPA regulation of water pollution from mining has fallen off sharply under the current administration because of a new agency rule that prohibits the EPA from pursuing polluters without the approval of local government. E&ENews.
Hottest Temperature Ever Recorded
What is believed to be the hottest temperature on record, 129.9 F, was recorded at Furnace Creek visitor center in Death Valley National Park on August 16, 2020. The previous high of 127.9 was recorded in Kuwait in 2011. The Guardian.
The unofficial highest temperature record has been unofficially broken
Breaking News: Scientists now have once again solved the mystery of how water got on Earth. But then again, maybe they haven't. NPR Report.
Opened as a railroad crossing bridge in 1917, converted to a pedestrian bridge in 1975, the popular Zink Dam Bridge in Tulsa has been closed.
Extensive use of tear gas during weeks of protests in Portland has prompted city officials to begin testing local water supplies for possible runoff contamination. More.
With news of water pollution from abandoned mines becoming more common, the outlook for controlling runoff from mines is not hopeful. “The Bureau of Land Management estimates that based on current staffing and resources, it will take 500 years for the agency to complete an inventory of abandoned hard rock mines and features on its land.” Pure Water Gazette.
For Us, the End of an Era: RIP purauv.com
We have taken down our popular two-decades-old website, www.purauv.com, because the manufacturer of the product has new plans for the brand name. Our site has been for years the definitive source of products, parts, and information for Pura-branded plastic housing ultraviolet units. But not to worry. The essential parts of the site still exist but in another place. We've incorporated the content into our main website, and how if you type in purauv.com you'll be redirected to https://www.purewaterproducts.com/pura-uv/ where you'll still be able to find Pura plastic UV units and every nut and bolt needed to maintain them. So you will understand why we shed a few tears at purauv's demise, the Pura #20 lamp, the standard replacement bulb for all Pura whole house UV units, has been our best selling product for many years.
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FAQ
This section always includes actual questions received since the previous Occasional and our actual answer.
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Question:
I’m looking into buying a whole house filter (https://www.purewaterproducts.com/products/bw011) with the Calgon Centaur media, mainly for chloramine removal. I have read the supplied data sheet, but haven’t been able to understand how to estimate how long the media would last before is fully saturated and needs to be replaced. Would you be able to help with figuring out an estimate?
Answer:
The short answer about media life is that there really isn't a practical way to predict the lifespan of carbon treating chloramine, but with residential backwashing filters, changing the carbon every 3 or 4 years is pretty common. The carbon lasts longest if the filter is adequately sized and the water is free of particulate. "Adequately sized" means large enough for the job so that the carbon isn't constantly challenged by service flow faster than it can handle comfortably.
The carbon doesn't actually have a "saturation" point. The removal process for chloramine (or chlorine) with carbon is not the same as with most chemicals. Chloramine isn't removed by a "grab and hold" process but is changed by a catalytic process. The chlorine and ammonia are broken apart, then the chlorine is changed to harmless chloride. The ammonia is left behind as a byproduct.
In theory, since it's a catalytic process, it could go on forever, but in reality the carbon is degraded in a number of ways. How long it lasts depends to a large degree on its having time to complete the treatment process. When service flow is too fast, the treatment is incomplete and the debris left behind takes its toll on the carbon. Think of it as what happens when you eat food too fast. As a rule of thumb, a cubic foot of catalytic carbon will treat chloramine optimally at the rate of 2.5 gallons per minute. Therefore, a 1 cubic foot (9" X 48") filter is being overworked a little if you run 4 gallons per minute through it. It will produce excellent water for residential use at 4 or 5 gpm, but the product won't be quite as good and the carbon won't last quite as long as it would if you were running it at 2 or 3 gpm. Most residential filters are undersized a little as a matter of convenience.
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Strong New Research Links PFAS Consumption to Reproductive Issues
by Peter Chawaga |
New research has underscored the pervasive health effects that can stem from one of the country’s most notorious drinking water contaminants — and it might become key in legal battles between consumers and the industrial operations responsible for introducing them into water systems.
The study looked at the health of residents of a Minneapolis suburb whose water contained elevated levels of per- and polyfluoroalkyl substances (PFAS), also known as “forever chemicals,” before the installation of a municipal water supply filtration facility in 2006, and compared it with health outcomes for the residents after the filtration facility was installed. It found that expecting mothers and newborns experienced some alarming consequences when exposed to PFAS in drinking water.
“Oakdale residents who drank water polluted with toxic ‘forever chemicals’ experienced elevated rates of infertility, premature births and low birthweight babies due to the contaminants, according to a multiyear review of health records,” the Star Tribune reported. “The authors of the peer-reviewed research … say it’s the first to establish a causal link between the chemicals and reproductive impacts.”
The research found that babies in this suburb were 35 percent more likely to weigh less than five-and-a-half pounds at birth, 45 percent more likely to be born before 32 weeks, and that the general fertility rate was as much as 25 percent lower than in communities whose water wasn’t contaminated with PFAS. These health outcomes trended closer to the norm once the filtration facility was installed.
“The research team said the study is the first to establish a cause-and-effect relationship between the filtration of drinking water containing high amounts of PFAS and better reproductive outcomes,” the Environmental Working Group explained. “Almost all previous studies have examined only the association between PFAS exposure and birth outcomes, not a direct cause and effect.”
Elevated levels of PFAS have been found in drinking water throughout the U.S. There are no federal limits on PFAS discharge, nor are there strict limits on PFAS levels in drinking water, though the U.S. EPA does maintain health advisories. A handful of states have taken their own action to reduce the presence of PFAS in source and drinking water.
As communities across the country look to hold industrial polluters responsible for the cost of removing PFAS from source water, the study may provide some critical legal ammunition. For instance, there are multiple lawsuits seeking damages from 3M and DuPont, two manufacturers of the chemicals.
“I think it will be used in litigation that has been filed and is going to be filed, not just here but in other countries as well,” former Minnesota Attorney General Lori Swanson, who has successfully sued 3M for $850 million in environmental damages in the past, told the Star Tribune.
Though the results of the study are jarring, they may prove to be useful data points in the fight to rid drinking water of these particularly insidious contaminants. If so, that might be one small silver lining to come from this Minnesota suburb’s struggles.
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Regulating Micro-plastics in Water
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The first step in regulating microplastics in water is defining microplastics
Before a contaminant can be regulated, it must first be defined. California recently approved the nation’s first definition of microplastics. Definition is the first step in requiring local suppliers to test drinking water for small plastic particles that could hurt human health. Other states are expected to take their cue from California.
Although chemical companies lobbied against the definition, the California regulatory board stuck to its original proposed definition: “solid polymeric materials to which chemical additives or other substances may have been added, which are particles which have at least three dimensions that are greater than 1 nanometer and less than 5,000 micrometers.” The definition excludes naturally derived polymers that haven’t been chemically modified, which can include “bioplastics” made from starch and other biomass.
This probably means that eventually drinking water agencies in California will have to test their supplies for plastic particles smaller than 5 millimeters and report their findings.
Regulation of plastics in water is uncharted territory, but California has now taken the first step.
Article adapted from Debra Kahn, “California becomes first state to define ‘microplastics’ in water.” from June of 2020. Politico
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Our Coconut Shell Catalytic Carbon Backwashing Filter for Whole House Treatment
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For City Water Treated with Either Chlorine or Chloramine
We've been selling whole house filters to city water users for several years in a variety of styles, with different carbon choices and different control valve configurations. This page features the best backwashing filter we can build for city water users. We present it in four basic sizes, with recommendations based on family size.
American cities use either chlorine or chloramine as a basic disinfectant. Both have advantages and disadvantages, but it’s no secret that when they reach your home they’ve done their job and you will like the water much better if you remove them from water that you bathe in and drink.
An issue in filter choice is although chloramine and chlorine are removed by filter carbon, chloramine is much harder to remove, so a specialty carbon known as “catalytic carbon” is the carbon of choice if your city uses chloramine. The high quality catalytic carbon used in the filters below is Aquasorb coconut shell catalytic. It is excellent for chloramine and much better than it has to be for chlorine removal. Aquasorb is a hard carbon for long life and it is exceptionally clean carbon that puts few if any carbon particles (fines) into home service lines.
The mineral tank is the water-saving Vortech and the control valve is the SXT electronic version of the tough and reliable Fleck 5600.
Unit Description
| Tank |
Black Vortech. No support bed needed. Excellent service flow. Saves thousands of gallons of backwash water over its lifespan as compared with conventional media tanks. 10 year manufacturer’s warranty. |
| Control Valve |
Fleck 5600 SXT. Digital version of the old faithful 5600. Programmed before shipping. Installer has only to set the time of day. Five-year manufacturer’s warranty. |
| Extras |
Stainless steel bypass. Drain tubing. Instructions for installation and startup. Support by phone or email. |
| Media |
The best carbon available. Jacobi coconut shell catalytic. Extra clean, effective for both chlorine and chloramine plus all the other chemicals that carbon removes. Extremely hard and durable carbon for a long life and minimum release of particles (fines). |
| Shipping |
Shipped UPS. We pay shipping. Ships within one or two days of receipt of order. |
| Recommended media replacement |
5 years. This can vary according to use and local conditions. |
Note: These filters are for homes with ¾” or 1″ service pipes. Please call for information about equivalent filters for larger applications.
| Part Number |
Tank Size. Media Load. |
Family Size Recommendation |
Full Price. (We pay shipping.) |
| BW011 |
9″ X 48 – 1 cubic foot. |
Chlorine: Up to 3 people.
Chloramine: 1 or 2 people.
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$699.00 |
| BW012 |
10″ X 54″ – 1.5 cubic feet. |
Chlorine: Up to 4 people.
Chloramine: 2 to 3 people.
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$819.00 |
| BW013 |
12″ X 52″ – 2 cubic feet. |
Chlorine: Up to 4 to 6 people.
Chloramine: up to 4 people.
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$929.00 |
| BW014 |
13″ X 54″ – 2.5 cubic feet. |
Chlorine: Up to 7 people.
Chloramine: Up to 5 people.
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$1,029.00 |
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Hydrogen Sulfide Removal From Well Water
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The “rotten egg” odor that people complain about in well water can come from many sources, but it is most commonly caused by “sulfur reducing” bacteria that give off a foul-smelling gas. The bacteria themselves are harmless–they don’t cause disease–but the gas they produce can cause horrible odors and smelly black staining in pipes and appliances.
In some parts of the country, most notably Florida, where hydrogen sulfide is common and very severe, the standard treatment is to spray the water into an open air tank, allow the noxious gas to escape into the atmosphere, then use a secondary pump to send the water from the tank into the home. Tanks of this type are expensive, need lots of space, and are subject to freezing in cooler climates. Therefore, another type of treatment known as “precipitation/filtration” is preferred in most areas.
With this method, an “oxidizer” causes the trapped hydrogen sulfide gas to “precipitate” to elemental sulfur, then the sulfur is trapped in a filter. It’s a two-step process. The filter is most often carbon. Filter carbon, especially a specialty carbon called “catalytic carbon,” can perform both steps–precipitation and filtration–but unless the amount of H2S (hydrogen sulfide) is small, the carbon wears out quickly and has to be replaced. However, when the carbon is helped by a more powerful “oxidizer,” the carbon can last a very long time and the process can be very successful. Many “oxidizers” can cause the precipitation of the gas: air, chlorine, hydrogen peroxide, potassium permanganate, ozone, and more. For residential users, the most practical and the most easily maintained are aeration (air) and chlorination.
A full treatment system with chlorine looks like this–
1. A dry pellet chlorinator — a device that drops chlorine pellets into the well itself– followed by a carbon filter, or
2. A chemical feed pump, installed before the pressure tank, that feeds liquid chlorine (household bleach) into the water line. After the pressure tank, you must have a retention tank–usually 80 to 120 gallons–to give the chlorine time to work. After the retention tank, a carbon filter.
A full treatment system with aeration looks like this —
1. An “Aer-Max” system, which consists of a 10″ X 54″ treatment tank that is fed by a small air compressor. It is installed after the pressure tank, and it is followed by a carbon filter, or
2. A “single tank aerator” installed after the pressure tank. It is a backwashing filter with a special control valve that draws in air to “oxidize” the H2S so that it can be removed by the filter carbon in the bottom 2/3 of the tank.
Here are page links that show the various strategies. Many have installation diagrams.
The carbon filter used in any of these systems (other than the single tank aerator) can be either a “backwashing” tank-style filter or a carbon block filter. If iron is present in the water, a backwashing filter must be used because a carbon block filter would be clogged quickly with iron.
Catalytic carbon is the carbon of choice with hydrogen sulfide, but any good carbon filter will work after proper oxidation.
Here are some places on our website to look for carbon filters —
Often the hard part of designing these filters is choosing and sizing the carbon filters. Do not hesitate to call or email us for help.
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TDS stands for “Total Dissolved Solids.” Solids might also be called dissolved minerals, ionic species, or salts. TDS is usually measured in ppm (parts per million) or mg/L (milligrams per liter), which are essentially the same. TDS is, in short, a measurement of all the dissolved mineral content of the water. A test for TDS does not measure chemicals or pathogens; a low TDS count does not mean that water is safe to drink.
TDS is measured often by laboratories with a conductivity meter, which quantifies the water’s ability to conduct electricity. The higher the mineral content, the better it conducts electricity. For more practical purposes, a TDS meter, which works on the same principle, is used. Conductivity is read in micromhos per centimeter. The familiar TDS meter, an inexpensive and very handy tool, converts conductivity to ppm TDS for convenience.
There is often confusion about TDS meters and what the readings mean. TDS meters measure the performance of reverse osmosis units, distillers, and deionizers, but except for limited use by professionals, they do not measure the performance of filters or water softeners. Softeners and filters do not affect TDS readings significantly. A softener, to illustrate, removes calcium and magnesium ions but the TDS reading will not be affected significantly because the softener adds a more-or-less equal amount of sodium in exchange. The TDS reading of softened water is usually slightly higher than the TDS of the untreated water. You need a hardness test to judge softener performance, not a TDS meter. Filters, especially when they are new, usually add TDS (the phenomenon is called “TDS throw”). Likewise, the performance of softener alternatives, either tank-style or electronic, cannot be measured by a TDS meter.
Although other TDS classifications may differ slightly, here is a good basic TDS breakdown from a publication of the Water Quality Association of America:
Water Type
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TDS, in mg/L
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Fresh Water
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<1,000
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Brackish Water
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1,000-5,000
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Highly Brackish Water
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5,000-15,000
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Saline Water
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15,000-30,000
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Sea Water
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30,000-40,000
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Brine
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40,000-300,000+
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Note that in standard usage these classifications are applied loosely. “Brine,” is used in water treatment for the salty water used to regenerate a softener or for the reject water from a reverse osmosis unit. In the case of the RO unit, the “brine” (a.k.a. “concentrate”) could be less than 50 mg/L in TDS. And although the song says that the moon was bright and shiny out on the briney, even sea water doesn’t technically qualify as brine. Similarly, saline often means any salty solution, and brackish is often used just to mean really bad water without specific reference to its TDS.
The EPA suggests an upper TDS limit for drinking water of 500, although many cities exceed this limit without dire consequences. For residential water use, when water gets above 1,000 TDS it is starting to border on being unusable, although some well owners grit their teeth and put up with problems like badly stained fixtures, stopped up plumbing, or water so high in sodium that it isn’t good for plants. Actually fairly high TDS water can be usable but it isn’t pleasant to deal with.
Hardness does not always result from high TDS. In our area in Texas, for example, much of the well water is high in sodium but naturally soft. If water has a TDS of 600 and a hardness reading of 2 grains (about 35 ppm), you can be virtually certain that it has a lot of sodium in it. If the high TDS consists mainly of calcium and magnesium (the hardness minerals), it can be softened, but the resulting water will be high in sodium.
Treating High and Low TDS
Treating low TDS is not common, but it can be done by using filters with a sacrificial medium like calcite. As water passes through the filter, it dissolves some mineral content and the TDS goes up. This can be done for point of entry (whole house) or point of use (drinking water only) applications. Small filters are now often used to “remineralize” reverse osmosis water. Minerals are dissolved by the low TDS water passing through the filter, raising the TDS count.
Lowering TDS is done by reverse osmosis, the most common method used in residential settings, distillation, or deionization. Reverse osmosis reduces TDS 90%+ (99% for larger, high pressure units), while distillation and DI (deionization) units can reduce TDS to a zero meter showing. Filters do not reduce TDS, not even the extremely tight ones.
Practical TDS Tips for Residential RO Users
The main use for a handheld TDS tester is to verify the performance of your RO unit’s membrane. While TDS is not in itself a targeted “contaminant” like lead, arsenic, or nitrates, the TDS meter verifies the health of the RO membrane. If the RO unit is reducing dissolved solids by 90%, you can be sure it’s also doing a good job on aluminum and fluoride.
The purpose of the TDS test is to tell you when to change your membrane. If you have an excellent TDS reading, that does not mean you don’t need to change your filter cartridges. The membrane should be changed based on need—as indicated by the TDS test—but cartridges are changed based on time. In fact, keeping the cartridges fresh is the best way to protect your membrane.
The worst time to do a TDS test is immediately after changing your filter cartridges. The new carbon postfilter will produce a “TDS throw” that will make your TDS reading high. Take a TDS test before you change your cartridges. The same principle applies to new RO units. You won’t get a reliable TDS test until the unit is a couple of weeks old. If you want to test shortly after installation, take loose the tube going into the storage tank and take your sample there—before the water goes through the post filter.
An acceptable TDS reading is a matter of personal preference. On our residential RO units, we usually change membranes when the unit consistently fails to reduce TDS by 85% or so.
To determine this, test first the tap water from the faucet, then compare it with the water coming out of the RO unit. This is called “% rejection,” and the formula is TDS of tap water minus TDS of RO water divided by TDS of tap water times 100. To illustrate, our local tap water usually runs around 180 TDS. So, if we test an RO system that shows a TDS reading of 15, the arithmetic would be 180 minus 15 = 165 divided by 180 = around 9.16 X 100 = about 92% rejection.
That’s fine.
The best advice is don’t obsess over TDS readings from a home unit. TDS is somewhat fickle and can be changed by variables like water pressure and the amount of water being used. Don’t be too quick to change a membrane if you get one bad test.
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Places to visit for additional information:
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Thanks for reading and be sure to check out the next Occasional!
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