Pure Water Occasional, January, 2023
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Greetings from Pure Water Products, the Pure Water Gazette, and the Pure Water Occasional.
In this mid-winter Occasional you'll hear about Groundhog Day, the meaning of absolute and nominal, arsenic in well water, TAC and the lathering of soap, the water content of the human brain, radon in water (and how to get rid of it), plastic in water filters (and how it's impossible to avoid it) , and much, much more.
Thank you for reading, and sincere thanks from Pure Water Products for your continuing support. We consider our greatest asset to be the many faithful customers who have kept us going over the years. (We are now starting our 37th year.) We really appreciate your support! A happy and prosperous Groundhog Day to all. |
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Thanks for reading!
Please visit the Pure Water Gazette, where you will find hundreds of articles about water and water treatment, and the Pure Water Products website, where there is much information about water treatment and the products we offer.
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Because weather plays such an important role in water availability and water quality, Groundhog Day ranks right up there with National Garden Hose Day as one of the planet’s most important holidays. Water is a constantly recycled commodity. Who gets it and in what condition and in what quantity is largely dependent on the Groundhog.
Groundhog Day started in Europe as a Christian holiday involving candles. It was called Candlemas Day. As with other holidays, its significance has been trivialized.
Because of the Bill Murray movie, most Americans believe that there is only one weather-forecasting Groundhog. Actually, spread across the US and Canada there are many places that honor their Groundhog as the True Groundhog. The commemorative statue above honors the late Wharton Willie of Wharton, Ontario. Whartonites consider Punxsutawney Phil a furry imposter.
So as we contemplate the prognostications of the Groundhog of our choice, we should remind ourselves that water is a gift to be regarded with reverence and that what is given can also be taken away.
Let the Groundhog Day festivities begin!
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Nominal and Absolute--What They Mean
Ratings of water filters that screen out particulate are usually stated in micron size. The micron is a standard measure of size that is used by filter makers. The diameter of a human hair is about 90 microns. Sediment filters are used to catch particles 1/300 of that.
Most sediment filters are given ratings by their manufacturers that describe their effectiveness at removing particles down to a specified size. The most common of these are”nominal” and “absolute.”
Nominal, according to the Water Quality Association (WQA), means that the filter will filter out at least 85% of the particles of the size it is rated for. In other words, a filter that is rated as a 1 micron nominal can be expected to pick out 85% of the particles that are 1 micron or larger from the water that passes through it.
Absolute, theoretically, means that the filter will reject virtually all of the particles of the given size. The usual expectation is a 3-log rejection–or 99.9%. Absolute ratings are usually used for the tightest filters and for purposes where efficiency really matters. For example, if a filter maker promises removal of E. coli, more or less 85% efficiency isn’t good enough. If you’re going to trust your life to the filter, you expect an absolute 3-log or 4-log rejection rating at the very least.
The problem with the absolute vs. nominal system is that there is really no universal standard that ensures uniformity. Some makers of filters for non-critical applications, for example, might consider 70% rejection suitable for a nominal filter. Definitions vary from one manufacturer to another, and there is really no way for the end user to verify the claim.
Beta Ratio is less frequently used. It establishes a ratio between the particles that are retained and the particles that pass through the filter. The formula is Particles In divided by Particles Out. Thus, the higher the Beta Ratio rating the better. A beta ratio of 1000 would mean that the filter allows only one particle per 1000 to pass through. A beta ratio of 100 means one particle per 100. The 1000-rated unit, therefore, is 10 times as effective. Note, however, that the beta ratio is no guarantee that the filter will perform as well in areas other than what it was tested for. The filter that works best in one application may not be effective in another.
Here are suggested maximum flow rates in gallons-per-minute for the four most common cartridge sizes in the popular Flow Max series of pleated sediment cartridges.
| Micron Rating | 2.5 X 9.75 | 2.5 X 20 | 4.5 X 10 | 4.5 X 20 |
| 1 Absolute |
3 |
6 |
8 |
12 |
| 0.35 Nominal |
4 |
8 |
9 |
13 |
| 1 Nominal |
4 |
8 |
10 |
15 |
| 5 Nominal |
7 |
14 |
15 |
25 |
| 20 Nominal |
8 |
16 |
15 |
25 |
| 50 Nominal |
10 |
20 |
15 |
25
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Sediment filters are essential tools in water treatment, but choosing one often requires some trial and error. The information presented above can help you make an intelligent choice, but the realities of your specific situation, which almost always involve unknowns like exact particle sizes and flow rate requirements, usually make it necessary to experiment.
The best sediment filter is one that cleans up the water with the least possible restriction in flow and has the longest lifespan.
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Water is Essential to a Healthy Brain
As a whole, the human brain is composed of roughly 73% water. Most of
the brain is made up of two kinds of tissue: gray matter and
(myelinated) white matter. The gray matter is about 80% water, while the
lipid-rich white matter has about 70% water content. Also, on average,
the water content of a female brain’s gray matter is 1.2% higher than
that of its male counterpart. Your brain’s high water content is among
the many reasons it’s essential to drink enough water each day, and part
of the reason dehydration impairs your focus, memory and mood.
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Does TAC (Template Assisted Crystallization) treatment make soap work better?
by Emily McBroom and Gene Franks
One of the much touted virtues of conventional water softeners is that they make soap lather better. Many a softener has been sold using in-home sales demos that fill the homeowner’s imagination with visions of sudsy showers, silky-soft laundry, and big bags of money saved on soap purchases.
With the salt-free TAC units, which aren't really water softeners but are often sold as substitutes for conventional softeners, the emphasis is usually on more mundane items like scale-free pipes and water heaters than on silky hair and spot-free dishes. We sell TAC units only with the promise that they will prevent scale buildup in pipes and appliances. As for soap performance, we always say we don’t know. Some customers have told us that soap does, in fact, lather better with TAC treatment and some aren’t sure.
To settle this weighty question once and for all, we decided to do a quick test.
One of the conventional tests that home-demo sellers have used to impress prospective customers is the simple soap demo. It is done with a dropper bottle of tincture of green soap and a small test bottle. You put some water in the test bottle, add a drop a soap, give it a shake, and see how much suds appears in the bottle. The result is predictable: The hard water sample is suds-free and the soft water sample is topped off with a big frothy head of suds.
Here’s what our test looked like when we tested untreated tap water, water softened with a conventional softener, and water treated with a small TAC unit that we made for the test.
1. Denton municipal tap water, untreated. Mildly hard: 6 grains per gallon (Hach titration test). Soap test result: almost suds free.
2. Denton municipal tap water processed by our office water softener: Hardness = 0 grains per gallon (Hach titration test).
The result: lots of lasting suds.
3. Finally, we tested tap water treated with a small TAC unit made with Watts Scalenet (OneFlow) media, 1/4 liter in a 9.75″ X 2.5″ filter cartridge in a standard-sized housing. The cartridge was rinsed for 5 minute rinse at 0.5 gpm, then tested. The result:
Hardness = 6 grains per gallon (standard Hach titration test). This is as expected. TAC units do not remove calcium and magnesium, which is what is being tested with a conventional hardness test.
Tested with the soap test: medium suds.
So that proves it. TAC improves soap performance. Although this is not a peer-reviewed, double blind test, and as far as we know no one has tried to verify the results, we’re satisfied that TAC-treated water makes soap lather a little bit better than tap water. (“Little bit” is a technical term that we use in testing to indicate an amount somewhere between “just a tiny bit” and “a whole lot.”)
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Radon In Water: How it gets there and How to Get Rid of It
Radon is one of the more perplexing and misunderstood issues in home water treatment. The material below is excerpted from several sources, especially from an excellent Penn State University Extension Services publication.
Radon is a colorless, tasteless, odorless, radioactive gas. It is formed from the decay of radium in soil, rock, and water and can be found worldwide.
The radon in the air in your home generally comes from two sources: the soil or the water supply. It escapes from the earth’s crust through cracks and crevices in bedrock, and either seeps through foundation cracks or through poorly sealed areas into basements and homes, or it dissolves in the groundwater. Radon can be trapped in buildings where it can increase to dangerous levels. Radon entering your home’s air supply through the soil is typically a much larger risk than the amount of radon in water. In general, radon is of much greater danger when it enters through the soil than when it enters via the water supply.
Radon can be inhaled from the air or ingested from water. Inhalation of radon increases the chances of lung cancer and this risk is much larger than the risk of stomach cancer from swallowing water with a high radon concentration. Generally, ingested waterborne radon is not a major cause for concern. The extent of the effects and the risk estimates involved are difficult to determine. According to the EPA’s 2003 Assessment of Risks from Radon in Homes, radon is estimated to cause about 21,000 lung cancer deaths per year. The National Research Council’s report, Risk Assessment of Radon in Drinking Water, estimates that radon in drinking water causes about 160 cancer deaths per year due to inhalation and 20 stomach cancer deaths per year due to ingestion.
Radon in water usually originates in water wells that are drilled into bedrock containing radon gas. Radon usually does not occur in significant concentrations in surface waters.
Dissolved radon in groundwater will escape into indoor air during showering, laundering, and dish washing. Estimates are that indoor air concentrations increase by approximately 1 pCi/L for every 10,000 pCi/L in water. For example, a water well containing 2,000 pCi/L of radon would be expected to contribute 0.2 pCi/L to the indoor air radon concentration. Based on the potential for cancer, the EPA suggests that indoor air should not exceed 4 picocuries per liter (pCi/L).
EPA and various states have recommended drinking water standards for radon in water ranging from 300 to 10,000 pCi/L but no standard currently exists. One study of radon present in over 900 Pennsylvania water wells found that 78% exceeded 300 pCi/L, 52% exceeded 1,000 pCi/L and 10% exceeded 5,000 pCi/L.
Since most exposure to radon is from air, testing of indoor air is the simplest method to determine the overall risk of radon in your home. Test kits for indoor air radon are inexpensive and readily available at most home supply stores.
Testing for radon in water is also inexpensive but requires special sampling and laboratory analysis techniques that measure its presence before it escapes from the sample. Test kits are available from various private testing labs.
The presence of waterborne radon indicates that radon is probably also entering the house through the soil into the basement which is generally the predominant source. Therefore, treating the water without reducing other sources of incoming airborne radon probably will not eliminate the radon threat. Therefore, you should also test the air in your home for radon.
Treating Radon in Water
The main objective of water treatment is removing radon from water before the radon can become airborne. Most water treatment, therefore, focuses on “point of entry” rather than “point of use.”
Granular Activated Carbon (GAC)
One method for removing radon from water is with a granular activated carbon (GAC) unit. Although these systems come in a variety of models, types and sizes, they all follow the same principle for removal . The standard radon GAC filter is a tank-style unit that can have either a backwashing control or a simple non-backwashing head. Non-backwashing GAC units must be protected from sediment with a prefilter. Radon filter sizing depends on the amount of radon present, service flow rates, amount of water treated, the size of the treatment bed and other factors, so each application must be considered separately and radon testing for effectiveness of the filter should be carried out regularly.
Typical setup for a GAC filter treating radon.
Various estimates suggest that GAC should only be used on water supplies with a maximum radon concentration of less than 30,000 pCi/L. If you do decide to purchase a GAC unit, select a filter size that matches your water use and conditions. According to EPA, a three-cubic-foot unit can handle as much as 250 gallons of water per day and effectively reduce radon levels. Typical water use in the home ranges from 50 to 100 gallons per person per day.
A major drawback to the use of GAC filters for radon removal is the eventual buildup of radioactivity within the filter. For this reason, the GAC unit should be placed outside the home or in an isolated part of the basement to minimize exposure. The carbon may also need to be replaced annually to reduce the hazard of accumulated radioactivity. Spent GAC filters used for radon removal may need special disposal. Disposal of spent carbon should be in compliance with local waste disposal regulations.
GAC treatment units are frequently also installed to remove chlorine, pesticides, petroleum products, and various odors in water. In these cases, the GAC filter may unknowingly be accumulating radioactivity as it removes radon from the water. Radon should always be tested for and considered as a potential hazard with the use of GAC filters.
Aeration
EPA has listed aeration as the best available technology for removing radon from water. Home aeration units physically agitate the water to allow the dissolved radon gas to be collected and vented to the outside. With new technological advancements in home aeration, these units can have radon removal efficiencies of up to 99.9%. Standard aeration treatment units typically cost $3,000 to $5,000 including installation. Be aware that aeration specifically for radon reduction is not the same as aeration for iron or hydrogen sulfide reduction. While “closed tank” systems designed for iron and sulfide reduction might help with radon, they are not designed to provide the large ventilation capacity needed to assure release of radon to the atmosphere.
When considering installation of aeration units, other water quality issues must be taken into account, such as levels of iron, manganese and other contaminants. Water with high levels of these types of contaminants may need to be pre-treated in order to prevent clogging the aeration unit. Disinfection equipment may also be recommended since some aeration units can allow bacterial contamination into the water system.
Typical Spray Aeration System Designed for Radon Reduction in a Private Home
There are several styles of aeration treatment units but all work on the same principle of aerating or agitating the water to allow the radon gas to escape so it can be captured and vented. Each type of unit has advantages and disadvantages. One of the more common styles is a spray aeration unit shown above. In this case, water containing radon is sprayed into a tank using a nozzle. The increased surface area of the sprayed water droplets causes the radon to come out of the water as a gas while the air blower carries the radon gas to a vent outside the home. About 50% of the radon will be removed in the initial spraying so the water must be sprayed several times to increase removal efficiencies. To keep a supply of treated water, a 100-gallon or larger holding tank must be used.
Another common aeration unit is the packed column where water moves through a thin film of inert packing material in a column. The air blower forces radon contaminated air back through the column to an outdoor vent. If the column is high enough, removal efficiencies can reach 95%.
Another type of aeration system uses a shallow tray to contact air and water. Water is sprayed into the tray, and then flows over the tray as air is sprayed up through tiny holes in the tray bottom. The system removes more than 99.9% of the radon and vents it outside the home. Go here for illustrations of other aeration systems.
Afternote from Pure Water Products: The most frequent call we get for radon removal equipment is for our AerMax aeration unit. AerMax is a superb product but it is not designed or intended for reduction of radon. AerMax adds air to water as pretreatment for the removal of iron, hydrogen sulfide, and manganese. It does not provide enough ventilation to serve as a treatment for radon or methane.
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Stainless vs. Plastic
A really good product that we’re happy to almost nevcr sell.
We get price and information requests for a product we hardly ever sell, the 4-cartridge Stainless Steel Filter with 2″ service ports from our website. There are currently several problems with this unit which include intermittent availablity, long waits for repair parts, and high initial price. We’ve taken the price off of the website because it goes up so frequently. We now ask potential customers to call for availability and pricing.
Our experience is that people interested in this unit are most frequently those who are intent on avoiding plastic. We always point out that although the housing is stainless steel, it requires radial flow cartridges which normally contain plastics, both on the end caps and the binding materials that hold the carbon in place. We just want to be sure people don’t buy a very expensive case just to avoid plastic when the case will only work with plastic cartridges.
We have plastic-housing options that cost less. For high flow sediment applications with for a 2″ water line, our Big Bubba unit is a much better value. Big Bubba handles high flow rates for sediment filtration with several (proprietary) cartridges available. It also has one carbon cartridge, which we recommend only for light duty service. Big Bubba, of course, consists of a hard plastic filter vessel and the cartridges all contain plastics.
For almost every case, we feel that the lower cost 20″ Big Blue housings for 4.5″ cartridges are a better value for residential and light commercial users. The more compact large housing units can be furnished for 3/4″, 1″, or 1.5″ pipe. They will easily handle 25 gpm or more as a sediment filter or up to the 7 gpm range as a carbon block filter. And what is even better, they can be installed in parallel to achieve any flow rate needed. We encourage parallel installations as the most practical solution for most residential and light commercial high flow applications. The case is hard plastic, not likely to leach plastic into the treated water.
In the age we live in, looking for a water filter without plastic is like looking for a window without glass. If no plastic is the objective, we aren’t sure what the answer is, but it isn’t our stainless steel whole house unit.
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Places to visit for additional information:
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Thanks for reading. The next Occasional will be out eventually--when you least expect it.
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