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

childinbathtub

 

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

groundhogcanadian

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.

fourstageupgrade

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.

 

addonfilter

 

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

 

newsboyThe leading water news stories of the past year

2017 was an eventful year. We saw several “top water stories” lists. What follows is Water Online‘s choice for the top three water treatment stories of the year.

 

  1. Awareness Of PFC Contamination

Just as the country’s lead contamination crisis dominated mainstream and industry headlines alike in 2016, drinking water contamination caused by perfluorinated compounds (PFCs) was among the biggest news for the treatment community in 2017.

Lead contamination has stemmed from the presence of corroded lead service lines in much of the country’s infrastructure, while the main sources of PFC contamination appear to be firefighting foam used by the Air Force and Navy and through the manufacture of industrial products such as Teflon.

The issue found its way into consistent news coverage thanks to concerned community members in Hoosick Falls, NY. Once the red flag around the health consequences of PFC-contaminated water was raised, communities all over the country found themselves to be similarly affected. Communities in Pennsylvania, Rhode Island, Washington, and elsewhere have all raised their own concerns around the issue.

While the U.S. EPA does not have any formal regulations that limit the presence of perfluorooctanoic acid (PFOA) or perfluorooctanesulfonic acid (PFOS), the two primary PFCs found in drinking water, the agency has issued a health advisory intended to guide utilities on just how dangerous they can be. The agency noted that exposure to PFOA and PFOS can result in development effects to fetuses, cancer, liver effects, immune effects, thyroid effects, and other health consequences. It sets a combined concentration of the two at 70 ppt, though the state of Michigan has proposed the much stricter limit of 5 ppt.

As the EPA balances the possibility of instituting stricter regulations on PFCs, it has launched a “cross-agency” effort to help address contamination and has become involved in some state-led investigations. Until further federal action, however, local municipalities are left to deal with the issue on their own.

  1. The Surge Of Fracking

While the practice of hydraulic fracturing, commonly known as fracking, did not emerge in 2017, it certainly saw an uptick.

A combination of growing oil prices and encouragement from the current political climate has seen domestic fracking production increase steadily all year and some federal estimates project all-time highs for barrels produced per day in 2018. As the fracking production rises, so to do the produced water treatment technologies that can enable it.

Hydraulic fracturing works by using high-pressure water to drill through rocks and access oil deposits beneath them. The wastewater that stems from this process is highly contaminated and must be treated to at least some degree before it can be returned to source bodies. Increasingly, that treatment happens onsite, utilizing some of the latest decentralized treatment technology to have emerged. New projects launched this year leveraged solar power and cutting-edge filter technology to help fracking operations handle their wastewater. The solutions encouraged by the rise of fracking in 2017 could very well yield new technologies suited for treatment operations all over the country.

But along with the rise in fracking popularity and technology, the debate over the threat posed to source and drinking water quality intensified as well. The U.S. EPA has at times conflicted itself over its take on the safety of fracking, including a report that it kept hidden a report on potential health dangers. This year also had its fair share of reports that the practice poses no threat to drinking water safety.

With the practice poised to grow in 2018, the water quality debates it inspires will grow as well, as too will the novel treatment technology solutions it inspires.

  1. The New-Look EPA

When Donald Trump was elected president in late 2016, it took much of the country by surprise. Throughout his tenure in 2017, it became clear that surprises were just about the only thing one could rely on when it came to his administration.

Trump’s departure from nearly every policy and stance established during the Obama administration has undoubtedly made its way to the EPA. As such, it has had a profound effect on the drinking water and wastewater regulations in this country and the work of treatment utilities therein.

The new-look EPA, headed by former Oklahoma Attorney General Scott Pruitt, can be summed up as one that is attempting to clear regulatory red tape for the nation’s businesses, which generally prefer fewer restrictions on their environmental practices. While this means that it is easier for treatment operations to adhere to their regulatory requirements, it can also pose challenges for keeping drinking water and source water safe.

For instance, the agency has been working hard to undo the Obama era establishment of the Waters of the U.S. (WOTUS) rule, which sought to clarify which source waters fall under federal jurisdiction. Trump has issued an executive order looking to rescind and replace the Clean Water Rule, which contains WOTUS.

The EPA has also been cutting back on staff, scientists, and budget, all in an attempt to reshape the agency to be less inefficient and to clear the way for progressive industrial practices.

It’s anyone’s guess what the Trump administration has in store for 2018, but it’s clear that the new direction of the EPA will continue to have effect on the country’s treatment operations.

 

Water and the Human Brain


Posted January 18th, 2018

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.

Salt Increase in US Rivers


Posted January 13th, 2018

US rivers need a diet of lower salt—or our drinking water will suffer

Researchers find an increase in salts and pH in nation’s waterways, putting aquatic organisms and drinking water at risk

roadsalt

As an Arctic blast of cold sweeps through most of the U.S., many of us see the salt trucks working hard to keep us safe—however, this generous spreading on the roads is part of a much larger problem in our water.

Roughly 37 percent of the drainage area—the land where precipitation falls off into creeks, streams, rivers, lakes—in the lower 48 states suffers from excess salts. But that’s just half the story: about 90 percent of these same drainage areas also have increased pH, which means they’re becoming more alkaline, according to a new study published  in the Proceedings of the National Academy of Sciences.

These two trends can spell trouble for wildlife, drinking water pipes, and, ultimately, our health.

We’re seeing a “change in the composition of salts,” said lead author, Sujay Kaushal, a researcher and professor of geology at University of Maryland. Different salts affect the pH of water in distinct ways and there’s been an uptick in the salts that make water more alkaline, a phenomenon Kaushal and colleagues dubbed “freshwater salinization syndrome.”

It’s the first study to tease out a link between increasing salinity and pH in our waters.

They examined U.S. Geological Survey data over the past 50 years. They didn’t just look at sodium chloride, which is what we put on fries, but a whole host of different sodium ions. These “cocktails” of salts can be more toxic than just one salt, Kaushal said.

Salt content and pH are “fundamental aspects of water chemistry, so these are major changes to the properties of freshwater,” said co-author, Gene Likens, president emeritus of the Cary Institute of Ecosystem Studies and a professor at the University of Connecticut.

There is the usual culprit of those road salt spreaders, but certain building materials—such as asphalt and gypsum—also contribute salts to waterways, Kaushal said.

“And there’s a cascading affect,” he said, “adding salts to the environment accelerates the release of more salts” that are within building materials and trapped in soils.

Elevated salinity and pH is a double-whammy: both can kill aquatic organisms. High salinity can trigger the release of toxic metals, carbon, nitrogen and phosphorous from nearby soils into streams.

Elevated pH and too much salt in water can also put our drinking water infrastructure at risk—making water more corrosive to surrounding pipes and allowing metals to leach into drinking water (such as what happened in Flint). Salts also can coat the linings of pipes, Kaushal said, and, if they build up, can constrict the flow of water.

High salt in water can spur high blood pressure in people on sodium-restricted diets.

“Given increasing impacts on ecosystems and human welfare, increased salinization and alkalinization of freshwater is now a pervasive water quality issue,” the authors wrote.

Some of the nation’s biggest rivers—including the Mississippi, Hudson, Potomac, Neuse and Chattahoochee rivers—had the most dramatic changes in salts and pH. The researchers point out that many of these rivers are also drinking water sources.

The U.S. Environmental Protection Agency does not regulate salts as drinking water contaminants.

Kaushal said there are some solutions, such as more discriminate, accurate spreading of fertilizers and road salts, or, for road salt, applying it as brine prior to big snows. “We have to maintain safety on our roads, but can we do this more efficiently?” he questioned, adding that some states and communities have started using organic de-icers and mixing salts with beet juice and sugars.

One way to prevent degrading building materials from releasing salts into water would be to regulate how close roads and developments are to waterways, he said.

Source: Environmental Health News.

Pure Water Gazette Fair Use Statement

 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 heart with visions sudsy showers, silky-soft laundry, and  big bags of money saved on soap purchases.

 

With the salt-free TAC units, 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 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 appear 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.  Mildly hard: 6 grains per gallon (Hach titration test).  Soap test result: almost suds free.

soaptesthardwater

 

 

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.

soaptestsoftenedwater

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.

soaptestscalenet

 

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.”)