Reverse Osmosis Remineralizing Filters

by Emily McBroom and Gene Franks


A product that has gained surprising popularity in the last few years is the “remineralizing” postfilter cartridge for undersink reverse osmosis (RO) units.

The process of reverse osmosis removes some 95% of water’s mineral content and, as a consequence, produces water that is temporarily low in pH.  For many years, vendors of non-RO drinking water systems have raised the argument (driven more by marketing than by science) that RO water lacks “healthful minerals” the body needs. This ignores the fact that our bodies obtain minerals readily and easily from the organic minerals in foods and really don’t need the difficult to assimilate inorganic minerals found in water. More recently, sellers of “alkalizers,” or “ionizer” machines which produce alkaline drinking water, have added fuel to the argument by claiming the pH of RO water is too low to be healthful.

To counter these arguments, RO vendors have created postfilter cartridges that add minerals while also raising the pH of low-mineral, slightly acidic reverse osmosis water. These cartridges are comprised mainly of two common water treatment minerals, Calcite and Corosex. Both have been used for decades in tank-style filters to raise the pH of acidic well water. Calcite is a pure form of crushed marble or limestone, refined into a granular medium suitable for use in a water filter. It works by dissolving slowly into the water, adding calcium and raising pH. Corosex is a brand name for manganese oxide, another natural mineral that dissolves to add magnesium and neutralize free carbon dioxide; thus, driving the pH down.  Calcite is a milder pH treatment than Corosex, so the standard mix in most filters is at least 4/5 Calcite.

For RO remineralizing filters, Calcite is the main ingredient, and a dash of Corosex can be added to give the pH an extra upward bump.  (Too much Corosex overcorrects and can produce alkaline, strong-tasting water.)


This simple inline cartridge manufactured by a leading filter company costs $16. It can be easily added to any standard RO unit. It contains Calcite to boost pH by adding calcium carbonate and improves the taste of the water with coconut shell carbon. It is inexpensive because it lacks any exotic ingredients.

While Calcite and Corosex are clearly the workhorse media of all RO remineralizing filters, an in-house survey of a dozen websites turned up a lot of other ingredients. Some ingredients were commonplace and some pretty exotic. It also revealed a wide range of prices and some interesting product claims.

Prices on the random sites we looked at go from $19.95 to $149 with the average around $65.

Here are some common product descriptions:

“Raises pH from 6.4 to 7.6.”

“Increases pH by 1.0-1.5 and provides alkaline water.”

“Increases pH, lowers ORP.”

“Remineralizes and raises the pH of water by at least 1 to 2 points.”

“Alkaline water. Boosts minerals and antioxidants.”

“To balance out and stabalize pH.”

“Makes water safer to drink.”

Provides “balanced mineral elution.”

“Balances the pH and puts essential minerals back into your water that your body can use.”

“Neutralizes acidic water, reduces leaching of metal plumbing components, and for use post RO to raise TDS.” (Obviously intended for multiple uses.)

Now for the ingredients.

There are the expected (Calcite and Corosex), the unexpected (KDF), plus a lot of exotic and unknown. Tourmaline figures prominently. According to Wikipedia, tourmaline is a semi-precious gemstone found in granite, pematites, and metamorphic rocks. It can also be found in sandstone. There is no indication what this might have to do with adding minerals to water, but one health and healing website explains:

Although it might be a stretch to say tourmaline has supernatural powers, it does have the uncommon and very special ability to generate an electric charge and emit negative ions and far infrared rays. Far infrared rays are invisible waves of energy. They’re able to penetrate all layers of the human body and reach the inner-most regions of tissues, muscles and bone. Through this, far infrared rays and negative ions gently soothe, stimulate and detoxify the body and mind. Negative ions are also incredibly important in determining mood.. . . Research has shown that mood disorders may be improved just as well through negative ion generators as antidepressants — but without the negative side effects. Why? Because these ions promote oxygenation to the brain and regeneration of the blood.

Other devices include neodyminium magnets (aka NdFeB, NIB, or Neo Magnet), whose contribution to RO water is not detailed.  Then there is Pi Ceramic,

[which is] . . . induced from the highly energized state of infinitesimal amount of ferric ferrous salts that have excellent antioxidant effect of protecting human bodies from active oxygen (free radicals) that causes various diseases and stresses (removing harmful active oxygen cause cancer, diabetic, hypertension, etc.), neutralization actions from harmful toxins (controls oxidation reduction reaction; detoxification action) and prevent rotting (inhibition of microbial growth, such as virus and bacteria) in the intestines. In addition, they have calcium antagonism (Calcium antagonist properties), high vital activation energy (Life energy), small water molecule structure, contains abundance oxygen, equal pH to body (pH balance), boost immune system, and bio memory and ability to transfer biological information. . . . 

Also there are Infrared Ceramics, which “. . .remove impurities from the water by cleaving the water molecule cluster. The impurity sticks to the ceramic, not allowing it to leach back into the water before it’s used.” Infrared ceramics, when used with tourmaline, according to one vendor, “help soften the surface tension, improve taste and increase drinkability.”

 There are ceramic negative ion balls that that are made mainly of tourmaline plus “kaolin and high-grade clay by nanometer comminution technology, special formula and agglomeration techniques. . . .”

Then there is “Super Ceramic” which “contains over 10 Minerals and imparts a pleasant taste to the water emitting even more Far Infrared Rays.”

Finally there is “Edox,” which we could not identify. It is most likely a brand name for one or more of the other ingredients mentioned.

Taste and Common Sense

Regardless of the exotics, the main ingredient of all remineralizing products is plain and simple Calcite. Calcite is mainly pure calcium carbonate, CaCO3. It is the principal constituent of limestone and marble. It may also have traces of other minerals such as manganese, magnesium, iron, boron, and bromine. (See

If you believe reverse osmosis water needs mineral supplementation to be “healthful” (we don’t!), RO water filtered through a small bed of Calcite will meet the requirement. And, if you want a pH above the low 7’s, you can buy a Calcite cartridge that has a just pinch of Corosex added to it.

Although water straight  from the RO unit is wonderful, we like Calcite filters because they can make exceptionally good tasting water. With or without remineralizing, pure reverse osmosis water tastes great and is the best value drinking water that can be produced in the home.



Plastics in bottled water

Time magazine reports:
Drinking from a plastic water bottle likely means ingesting microplastic particles, a new study claims, prompting fresh concerns — and calls for scientific research — on the possible health implications of widespread plastics pollution.
A study carried out on more than 250 water bottles sourced from 11 brands in nine different countries revealed that Microplastic contamination was nearly universal, found in more than 90% of the samples.
The study found an average of 10.4 microplastic particles about the width of a human hair per liter. That’s about twice the level of contamination discovered in the group’s earlier study on the ubiquitous plastic contamination in tap water across the globe, with the highest rate found in the U.S.
Previous studies have found that a large portion of the microplastic particles found in our oceans, lakes and rivers, as well as in fish stomachs, can be traced back to the washing of synthetic clothes.
In the case of bottled water, Orb’s new study indicated contamination was partly the result of plastic packaging, and partly the fault of the bottling process. The survey included brands like Aquafina, Dasani, Evian, Nestlé and San Pellegrino.
It’s unclear what effect, if any, this consumption of tiny bits of plastics has on human health. As much as 90% of ingested plastic could pass through a human body, but some of it may end up lodged in the gut, or traveling through the lymphatic system, according to research by the European Food Safety Authority.
Also unknown is what chemicals are contained in the plastic particles.

Ultrapure Water

Posted March 7th, 2018

Ultrapure Water Is Not for Drinking

What is commonly referred to as “ultrapure” water goes beyond what is considered pure drinking water. In fact, it is not considered “fit” for human consumption. It is water so clean that it is used as an industrial solvent for cleaning semiconductors, producing pharmaceutical products. and for cooling in power plants.

Typical production of ultrapure water includes use of microfiltration membranes to remove particles from the water, ion exchange and reverse osmosis (RO) membranes to remove ions,  UV light to kill bacteria and degassing membranes to remove dissolved oxygen.

We think of reverse osmosis, which can turn sea water into excellent drinking water, as taking “everything” out of water, but when it comes to water needed for many technical processes RO water isn’t even near clean enough. Ultrapure water requires 12 filtration steps beyond RO with the final filter having pores 20 nanometers in width.  (Twenty nanometers is 0.02 microns.)

Installation and Startup of Fleck 5600 and 2510 Backwashing Filters:

A Non-Technical Guide to Installing and Putting into Service the Pure Water Products Standard Backwashing Filters

Here are the steps involved in setting up and starting up your backwashing filter.

1. Check to make sure you have all the parts before you start.

2. Select your installation site and put the filter in place.

3. Load the media into the tank and screw on the control valve.

4. Connect the filter to your plumbing.

5. Run water into the filter and check for leaks.

6. Allow adequate time for the media to soak.

7. Backwash the filter, then run one or more full regeneration cycles.

8. Put the filter into service and start using the water.

Here’s an expansion of the steps presented above.

1. Parts List

You should receive:


You should have a mineral tank and one or more boxes of filter media.

1. A large tank called a “mineral tank.” Most of our filters use Vortech (Enpress) tanks. There will be a tube called a “riser” or “dip tube” permanently installed in the tank and visible through the hole in the top. The tank size will be stated on a decal on the side of the tank near the bottom. “1054” means the tank is 10″ in diameter and 54″ tall, for example. “0948” means the tank is 9″ in diameter and 48″ tall.

2. A box or multiple boxes of the filtration medium that goes in the tank. Be sure you have enough before you start. Here are the common residential tank sizes and the media amount they hold:

0844 – 3/4 cubic foot.

0948 – 1 cubic foot.

1044 – 1.25 cubic feet.

1054 – 1.5 cubic feet.

1252 – 2.0 cubic feet.

1354 – 2.5 cubic feet.

Vortech mineral tanks require no gravel underbed, so the filter medium is all you will be putting into the tank. It should fill the tank about 2/3 full.


Funnel, drain tubing, stainless steel bypass valve, and filter control valve.

3. A blue funnel to pour the media in with.

4. A stainless steel bypass valve, with either 3/4″ or 1″ ports.

5. Drain tubing. In most cases, 25′ of flexible 1/2″ drain tubing. (No drain tubing is included with larger 2510 filters that require more than 7 gallons-per-minute drain flow.

6. The control valve. It will be one of these listed below. (Fleck does not put product names on its control valves, but you can identify your control valve from our main website.

5600 Timer

5600 SXT (Electronic timer)

5600 AIO (Aeration)

2510 Manual (non-electric)

2510 Timer

2510 SXT

2510 AIO (Aeration)


The control valve will have a tag near the drain port designating the flow control device installed in the filter. It will be one of these: 4, 5, 6, 7 gallons per minute. Fleck 2510 iron filters for larger tanks will have a drain line cartridge with the gallons per minute (gpm) rating stamped on the side.


2. Select a Place for Installation

The filter should be installed in a place where it will treat all the water going into the home. Usually, irrigation lines will be excluded. Most filters need access to a drain and a 110 volt electrical source. Drain water from a filter, unlike a water softener, is just water. So, if it is feasible, drain water can be directed to water plants. Keep in mind that the filter will at some time require maintenance and probably a media change, so put it in a place that gives you access. If installing outdoors, the filter will need protection from freezing, direct sunlight, and rain. Unless earthquakes are an issue, there is no need to secure the filter with straps, but it needs a good, solid, level surface to stand on.  

3. Load the media into the tank and screw on the control valve.


Put tape or a small plastic bag over the open end of the tank’s riser tube to prevent media from going into the tube.  Don’t forget to remove the tape after the media is loaded. And clean any media dust out of the tank threads before screwing on the control head.

Using the funnel provided, pour all of the filter media into the tank. No gravel underbed is needed. Before you start, cover the top of the riser tube centered in the tank with duct tape or with a small plastic bag so that media cannot get into the tube. Media that goes into the tube will end up in your house lines. Filter media, especially carbon, are dusty, so it’s a good idea to wear a face mask while pouring media into the tank. The media will not fill the tank completely. In most cases, the tank will be about 2/3 full. When the granular filter medium has been loaded, clean the tank threads of media dust and screw the valve onto the tank. (The riser goes into the center hole of bottom of the control valve.) Hand tighten until snug. No tool needed.

4. Connect the filter to your plumbing.

bypassclampThe bypass valve connects to the control valve body with clamps. A small amount of wiggle is normal after clamps are tightened.


Fleck 2510 Control with Bypass installed.  Note that the bypass valve is in bypass position.  When in bypass mode, the valve sends water around the filter to the home. The “Service” setting sends water through the filter and to the home. 

The stainless bypass connects to the o-ringed adapter and is secured by two clamps. Slide the bypass into place and tighten the clamps snugly. It is normal for there to be some “play” in the finished assembly.

The bypass ends in 3/4″ or 1″ female pipe thread. Connect to your plumbing using standard plumbing teflon tape or liquid teflon. Teflon tape is the standard.

Note that water enters the filter from the left (looking at it from the pipe installation side). Follow the directional arrows on the bypass.

Connect to a drain following your local plumbing code. The filter comes with flexible tubing that slips onto the barbed fitting on the control. (Adding a hose clamp is recommended.) If you prefer to hard-pipe the drain, remove the barbed fitting and connect to the female thread.

We highly recommend installing a shutoff valve in the pipe coming into the filter.

5. Run water into the filter and check for leaks.

Put the bypass valve in back of the filter into Service position.

Plug in the control valve.

Before sending water into the filter, it’s best to put the control valve into Backwash mode. This will allow water to flow upward through the filter and out the drain line, protecting the home’s service lines from debris coming from the unwashed media.

Here’s how to put the control valve into backwash position:

For mechanical timer valves (no digital display), turn the large center knob on the timer face clockwise. With the 2510, click the center knob one click and you will hear the motor engage. Allow a minute for the piston to move into place and the unit will be in backwash position. With the 5600, advance the knob slowly clockwise a few clicks until you see the beginning of a word in the viewing slot. Wait one minute, then unplug the valve.

For SXT electronic control valves, push the button on the left side of the face and hold for five seconds or until you hear the motor engage. Wait for the motor to move the valve to backwash mode. When “BW” shows on the display and the time (e.g. 10:00) begins counting down backward, unplug the valve.

The unplugged valve will remain in backwash position.

Open the water inlet valve halfway and allow water to slowly fill the tank. Take your time.

When the tank is full and water is running smoothly (but slowly) from the drain line, turn off the water and allow the media to soak.

6. Allow adequate time for the media to soak.

During the media soak, placing the bypass valve into Bypass position will send unfiltered water into the home.

There are no hard rules about how long the media should soak. Half an hour is enough for most media. Some manufacturers ask for a longer soak:

ChemSorb –24 hours.

Carbon – 24 hours.

Katalox Light – Long soak and extended backwash.

In addition to media loss, the consequences of inadequate soaking can be excess air in service lines (especially with carbon), small particulate in service lines, cloudy water for a time, and sometimes a metallic taste. Initial service water with Katalox Light is unpredictable: sometimes it puts out a fine film that lasts for days, sometimes a metallic taste, and it almost always produces high pH and high alkalinity. These issues eventually go away. 

7. Backwash the filter, then run a full regeneration cycle.

After the media has had a good soak, return the bypass valve to service position, open the inlet valve all the way and plug the control valve in. The backwash will resume, now at full speed. Let the control valve finish the entire cycle (backwash and rinse).

Finally, open the downstream faucet nearest the filter and let water rinse from the faucet at least ten minutes. The water should run completely clear.

If you feel that more backwash and rinse are needed, simply repeat the regeneration cycle.

Can Earth’s Fresh Water Survive the Phosphorus Overload?

Man-made phosphorus pollution is reaching dangerously high levels in freshwater basins around the world, according to new research.

Phosphorus is a common component of mineral and manure fertilizers because it boosts crop yields. However, a large portion of phosphorus applied as fertilizer is not taken up by plants, and either builds up in the soil or washes into rivers, lakes and coastal seas, according to the study’s authors.

The results of a new study show global human activity emitted 1.62 million U.S. tons of phosphorus per year into the world’s major freshwater basins, four times greater than the weight of the Empire State Building.

The study also assessed whether human activity had surpassed the Earth’s ability to dilute and assimilate excess levels of phosphorus in fresh water bodies. The authors found phosphorus load exceeded the assimilation capacity of freshwater bodies in 38 percent of Earth’s land surface, an area housing 90 percent of the global human population. There is simply not enough fresh water in many areas to assimilate the phosphorus.

The study’s results indicate freshwater bodies in areas with high water pollution levels are likely to suffer from eutrophication, or an excess level of nutrients, due to high phosphorus levels. Eutrophication due to phosphorus pollution causes algal blooms, which can lead to the mortality of fish and plants due to lack of oxygen and light. It also reduces the use of the water for human purposes such as consumption and swimming.

Breaking down phosphorus load
The authors of the new study examined agricultural activity to calculate the total amount of man-made phosphorus entering Earth’s surface water from 2002 to 2010. They gathered data on how much fertilizer is applied per crop in each country, and estimated domestic and industrial phosphorus production by looking at protein consumption per capita per country.


The largest contribution to the global Phosphorus load came from domestic sewage at 54 percent, followed by agriculture at 38 percent and industry at 8 percent.

The authors found the phosphorus load from agriculture grew by 27 percent over the study period, from 525 gigagrams (579,000 U.S. tons) in 2002 to 666 gigagrams (734,000 U.S. tons) in 2010.

About The American Geophysical Union
The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing 60,000 members in 137 countries.

SOURCE: The American Geophysical Union.  Via Water Online.




How Much Do Permeate Pumps Contribute to TDS Creep in Home RO Units?

by Gene Franks

The permeate pump has become a popular option for undersink reverse osmosis units. The “pump” doesn’t increase inlet pressure, as an electric booster pump does, but enhances RO performance by isolating the RO membrane from back pressure from the storage tank. It uses energy taken from the brine (drain) flow to power the product water (permeate) into the pressurized storage tank. The permeate pump saves water, no doubt about it, and is assumed to improve water quality, as measured by TDS performance, as well.

One of the controversial issues with the permeate pump is whether it should be installed with or without a standard auto shutoff valve (ASO), the device that turns standard RO production off when the unit’s storage tank is full.

permeatepumpmodelMysterious action of the non-electric permeate pump. Click on picture for animated version.

If installed without a shutoff valve, the pump itself shuts down production when the tank is full. With this arrangement, the tank is filled to almost 100% of the pressure of the tap water. The high tank pressure is especially advantageous in low pressure situations, such as wells set up to send pressures as low as 30 or 40 psi to the home.

If the permeate pump is installed with the regular shutoff valve, the valve shuts down production when the storage tank pressure reaches about 2/3 of the tap water pressure. I

The reason most permeate pumps are now installed with the ASO in place, in spite of giving up a little pressure at the faucet,  is to combat a phenomenon called “TDS creep” that occurs when the RO unit sits unused. Without the ASO to form a physical wall between incoming tap water and the RO membrane, the dissolved solids count “creeps” upward because the natural forces of osmosis are still at work.

TDS stands for “total dissolved solids” and the TDS count is a theoretical sum of all the minerals dissolved in the water.  Testing TDS is a standard way to evaluate reverse osmosis performance. The lower the TDS reading, the better the unit is working.

I decided to give the TDS creep problem a real world test with my home RO unit running with three different configurations to see if much dreaded TDS creep really matters significantly in home units. The chart below shows the three formats and the results.

I took 16 tests in each of three categories, all in the morning, testing the first water out of the unit after a night of inactivity. TDS creep occurs when the unit is not producing water. In all, the testing spread over 12 consecutive days. I tested the first glass, the second glass, the third glass, and then emptied the tank half way and took a test there. As expected, the first and second glasses usually but not always had the highest TDS readings no matter what format the RO unit was arranged in.

Testing wasn’t done with high dollar lab equipment but with my trust HM TDS-3 handheld tester, the same tester we send out with our Black and White RO units.

A tap water TDS reading was taken before each group to provide a “base line” and results below are expressed as “% rejection” rather than actual TDS numbers. (“Percent rejection” means tap water TDS minus RO TDS divided by tap water TDS. It expresses the percentage of the total dissolved solids (minerals) in the water that are being rejected by the membrane. The higher the percentage, the better the membrane is working.)

The column on the right is the significant figure. It shows the average of all 16 tests taken in the category.

Product Setup

Lowest Reading–% rejection

Highest Reading–% rejection

Average — % rejection

Permeate Pump with Auto Shutoff Installed

89% 96% 93.50%

Permeate Pump with Auto Shutoff Absent

89% 97% 91%

Standard Setup: Auto shutoff, no permeate pump.

92% 97% 95.25%

As expected, the “first water out in the morning” TDS performance of the unit with permeate pump was better with the shutoff valve than without.  It was totally unexpected, however, that the best performance of all was the standard setup unit with the conventional shutoff system and no permeate pump. I have no explanation for this, but I should mention a couple of variables.  One is that the membrane used is the GRO 50/50, a stingy water-saver that puts out a much reduced brine flow to drive the pump. The pump seems to run fine with the GRO, but starvation of brine water to power the pump might matter. Also, the pump itself is an older version ERP 1000, and the newer, quieter ERP 500 might be a better match for the membrane.

The final word, though, is that although the TDS performance of the permeate pump unit with the shutoff valve seems a bit better, for residential units with lots of stop and go use, I doubt that the difference is worth worrying about. This tiny trial certainly doesn’t give a definitive answer, but I suspect the result from my home unit is typical of what happens in most home installations.

Radium in Texas Water

Posted February 5th, 2018

Radiation in Water Reported by the Environmental Working Group

The nonprofit Environmental Working Group (EWG) evaluated data from a five-year study that ended in 2015 and found radium in water in all 50 US states.

The state with the most widespread contamination, according to EWG, is Texas, where more than 3,500 utilities serving more than 22 million people — about 80 percent of the state’s population– reported finding radium.

“Radium and radon are potent human carcinogens. Radium, via oral exposure, is known to cause lung, bone, head (mastoid air cells), and nasal passage tumors. Radon, via inhalation exposure, causes lung cancer,”  according to an EPA fact sheet.

Radium is a contaminant with a relatively high EPA limit.  California’s limit is much lower, and a large number of US water systems which pass US standards would exceed California’s.   According the EWG: “Almost all exceeded California state scientists’ public health goals for two separate radium isotopes, set in 2006, which are hundreds of times more stringent than the EPA’s standard for the two isotopes combined. The elevated risk of cancer, as well as potential harm to fetal growth and brain development, decreases with lower doses of radiation but does not go away.”

Main Source:  Water Online




Is Fluoride Absorbed Through the Skin?

By Emily McBroom and Gene Franks



We discovered an amazing fact about municipal water fluoridation.  Although this seems incredible, city water suppliers, at the recommendation of government health officials and independent groups like the American Dental Association, have been dosing fluoride into municipal water supplies for several decades although no one has yet bothered to find out to what extent fluoride in water is absorbed through the skin.  Although there have been a few studies buried deep in academic archives that dance around the subject of human uptake of fluoride through the skin, there is certainly no clear-cut understanding of the issue as there is, for example, with the dermal uptake of chlorine.

The absorption of chlorine through the skin has been studied and well established.  Studies we’ve done regarding the uptake during bathing of contaminants like lead and arsenic have yielded a lot of information. Not so with fluoride.

Although we did some general searching, we spent a lot of time reading the references from the website of an active and research-oriented anti-fluoridation organization, the Fluoride Action Network (FAN), with the assumption that if evidence exists that fluoride is taken up through the skin an organization looking for reasons to end fluoridation of tap water would find it.  Searches of the FAN site and general searches of the web, however,  reveal that specific studies that focus on absorption of fluoride through the skin do not exist. Most studies of contact of fluoride on human skin focus on hypersensitivity to fluoride through ingestion and topical use inside the mouth.

One study indicates, for example, that fluoride can penetrate the mouth’s mucous membrane but does not cross the skin barrier. There are studies of the reaction of the skin to contact with fluoride such as contact dermatitis, inflammation, skin lesions, and rashes. There are studies documenting human hypersensitivity to fluoride and many studies about allergic reactions to fluoride. There’s a scholarly study showing that fish (in this case Siberian sturgeon) take up F- directly from water and it is extremely detrimental to their health.  There are studies involving application of fluoride to the shaved leg of a rat and an ambitious study on the question of permeability of fresh and frozen human skin and fresh and frozen pig skin of anions including fluoride.

Most of this seems only remotely related to the real questions we should be asking about how much fluoride does a real, live human take in by bathing or showering with fluoridated tap water. We know that the fluoride load on the human body is cumulative. Fluoride is stored in the bones and teeth.  How much fluoride does a small child accumulate by playing for hours on a summer afternoon in a pool filled with fluoridated tap water? How much fluoride does a teenager accumulate through the skin and through the air during an hour-long shower? How much fluoride does a competitive swimmer take in during a long practice session in fluoridated pool water?

Although we find no studies that address these questions,  there are some publications that make general assumptions with little research to back them up.

For example, there is a reassuring essay by the European group The Scientific Committee on Health and Environmental Risks (SCHER). SCHER examines in detail the amount of fluoride one might get from drinking water, swallowing toothpaste and other oral means of ingestions, but passes the dermal absorption issue off lightly:

No experimental data on the extent of dermal absorption of fluoride from dilute aqueous solutions are available. As fluoride is an ion it is expected to have low membrane permeability and limited absorption through the skin from dilute aqueous solutions at near neutral pH (such as water used for bathing and showering). This exposure pathway is unlikely to contribute to the fluoride body burden.

On the possibility of inhalation during showering, SCHER says:

No systematic experimental data on the absorption of fluoride after inhalation are available. A few older occupational studies have shown uptake of fluoride in heavily exposed workers from fluoride-containing dusts, but it is unlikely that inhalation exposure will contribute significantly to the body burden of fluoride in the general population

See full article.

Similarly, a publication of the New Hampshire Dept. of Environmental Service seems to say that fluoride can be taken in through the skin and through breathing but that in the real world this isn’t a big problem:

Fluoride can be absorbed from the gastrointestinal tract after ingestion, following inhalation, and through the skin. Soluble forms of fluoride, such as those added to fluoridate water, have been found to be absorbed at an efficiency of 90 percent or greater. Of the ingested fluoride that remains in the body, 99 percent is incorporated into the bones and teeth. Inhalation and skin absorption can be significant for some occupational exposure situations, but are not important exposure routes for fluoride in drinking water.
We take that by “drinking water” they mean fluoridated tap water.
Our Conclusion

Since there is no hard evidence on the uptake of fluoride through the skin, at least none that we can find, we can rely only on common sense. Since fluoride is a potent poison that can kill and disable when ingested in amounts a bit larger than the accepted public water dosage, it seems implausible that significant quantities of fluoride are being taken in through the skin via exposure to fluoridated water. If fluoride were entering the body via the skin in large quantities, it would become obvious quickly in the form of fluoride poisoning in high risk groups like swimmers, people who take long showers and baths, and those who have prolonged workplace exposure to fluoridated water.

We are, therefore,  sticking with our own belief that fluoride is a significant issue when taken in by mouth but not so much when exposure comes via bathing or breathing.

From a practical standpoint, we take the same position that we do on lead and arsenic. We do not recommend “whole house” fluoride treatment.   We feel that fluoride is a drinking water issue and that residential users should use a proven drinking water fluoride treatment–undersink reverse osmosis is the best–and make a point of drinking water only from their water treatment system. Whole house fluoride treatment is both impractical and unnecessary.

Groundhog Day

Posted January 30th, 2018

Happy Groundhog Day


Because weather plays such an important role in water quality, Groundhog Day should rank right up there with National Garden Hose Day as one of the planet’s most important holidays. Water quality and availability are only partially within our control.

Groundhog Day started in Europe as a Christian holiday involving candles, 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!


Adding an Inexpensive Remineralizing Cartridge to Existing RO Units


There is increasing interest in adding mineral content back into reverse osmosis water.  Raising the mineral content also raises the pH, and according to many, improves the taste of low-pH RO water.

This can be accomplished easily by adding a simple post-filter containing Calcite or Calcite combined with a small amount of  Corosex (aka FlowMag).  Both are standard water treatment minerals available in NSF Standard 60 brands that are regularly used to raise pH of acidic well water and as post treatment for “whole house” reverse osmosis units. Calcite is natural calcium carbonate made from crushed granite and FlowMag is magnesium oxide. They add back to the water natural calcium and magnesium plus whatever trace minerals are present in the natural sources.


The picture above shows the easiest way to add a calcite filter.  The inline filter on the very top is a Calcite/coconut-shell carbon  postfilter added after the unit’s regular post filter (white housing).  It provides some extra carbon, a bump in pH, and added minerals.  It makes excellent tasting water, is inexpensive, and is easy to replace.  Total cost of the cartridge, the clips to hold it, and the fittings is around $30.

Another way to add a remineralizing stage to your existing RO unit is to add a free-standing full-sized Calcite/Corosex cartridge after your present post filter.  With this method you simply add the remineralizing filter into your faucet line, between the current post-filter and the faucet. The remineralizing unit shown below connects easily with quick connect fittings in the same size as your present faucet line.




Round number cost of adding the free-standing add-on calcite filter, for filter, bracket, fittings and one cartridge, is about $60.