Rinsing Water Filter Cartridges: Getting the Air Out

by Gene Franks

When water filter owners ask how long they should rinse the filter cartridges in new water treatment units, or in units they are replacing the the filter cartridges in, they usually expect a simple answer and that’s what they usually get.  Actually, though, the answer can be quite complicated and in most cases there is not a pat answer.

We’re concentrating on carbon filters here, which are by far the most common in residential treatment units, but the same principles apply in varying degrees to other media, like calcite, ion exchange resins, or activated alumina.

Fines

If you have a carbon filter, you’ve probably noticed that a big blast of black stuff comes out of the faucet when you start up a new cartridge. This is called “carbon fines.” It’s just manufacturing left-overs,  small pieces of carbon that have to be washed out.  Some filters, you may also have noticed, put out virtually no fines. This is because the manufacturer has gone to the trouble to clean the carbon up well (often washing it with acid) to keep the “fines” from going into your RO membrane or your refrigerator.

The assumption is that when the fines have subsided and the water is running more or less clear, the cartridge is ready to use. Not so.  There are other considerations.  For example, brand new carbon filters can contain residuals of contaminants (like arsenic), and even NSF Standard 42 cartridges, which are certified to be safe, sometimes are labelled with the admonition to “place the cartridge in an appropriate housing and rinse for a minimum of 20 minutes before use.” Anyone who has tested a reverse osmosis unit after a cartridge change knows that you do not get a valid TDS (total dissolved solids) reading of membrane performance after the cartridge change.  This is because the new carbon postfilter, for up to a week after the cartridge change, is putting out “solids” that the meter can see but the human eye cannot. To be clear, the same “TDS throw” occurs in all new carbon filters, not just RO postfilters; it’s just that only RO units are routinely tested for TDS performance.

AirWhat air inside a carbon block cartridge looks like

A fact that water treatment professionals are aware of but that water filter users seldom consider is that new carbon filters are mostly air. What makes carbon such an amazingly effective filter medium, in fact, is not only what is there but what is not there. It’s the countless tiny air-filled pores inside the carbon particles that provide enormous amounts of surface area for chemical contaminants to cling to that make carbon so effective.   The so-called “40-40-20” rule has it that most carbon filters are 40% air-filled space between carbon particles, 40% air-filled inner pores, and 20% actual solid carbon. In fact, depending on the type of product and the manufacturing method, most carbon filters are said to be 70% to 90% air.

When a new cartridge is put into service, it can take days for the air to work out completely. That’s why users sometimes experience cloudy water (if air is causing the cloudiness, the water in a glass will clear from bottom to top) and why there sometimes appears be a scummy substance at the top of a glass of water from a new filter. The scum is air trapped under the “skin” at the top of the water column.  Both the cloudy color and the scum will go away with time, and it’s nothing to worry about.

Diminished Performance Because of Air

While fines and trapped air are aesthetic problems with filter startup that goes away fairly quickly, there is actually diminished performance from a new filter cartridge or carbon bed in a large filter caused by trapped air that lasts longer.   I sometimes tell customers with new products that the water will taste and look better after a week or so,  when the new filters have had a chance to “mellow in.”  Mellowing in is a low tech way of saying that everything will work better when water has had a chance to push the air out of the millions of tiny crevices within the carbon, thus allowing the water to come into intimate contact with the carbon itself.

Large industrial filters have to be soaked for long periods after rebedding to drive the air out the carbon.  Hot water, which speeds the process up, is also used.  Henry Norwicki et al. in a recent Water Conditioning and Purification article actually recommend a 72 hour soak for small filter cartridges:

There are two ways to replace the nano-spaced concentrated air: 72 hours submerged soaking in tap water or using hot water to remove trapped air. Water forms larger conglomerates by hydrogen bonding of water molecules. Conglomerates of hot water are smaller and can better penetrate adsorption spaces than larger, cold-water conglomerates. Replacing filter soaking water with fresh water and turning the filter vertically upside down is also beneficial. Draining helps remove air bubbles. When air in nanospaces is replaced by water, bubbles go into bulk volume between media particles. Simple draining removes these bulk water bubbles. Water inside particles, however, is not removed by draining. Soaking for 72 clock hours is necessary and extra time is acceptable.

We’re a long way from recommending that customers soak filter cartridges for 72 hours before using them, but it helps to know what’s going on inside the filter and be a bit forgiving if water is cloudy and doesn’t taste as good as you would expect with brand new filter cartridges.

Enlargement of granular carbon shows countless pores that adsorb contaminants. The surface area of the pores is exceptional. A single pound of activated carbon has more surface area in its pores than 100 football fields. When the carbon is new, these pores are filled with air that must eventually work its way out.

New Technologies That Save Water Should Be Taken with a Grain of Salt

Many water saving products work well, and yet  . . .

Vortech Tanks

Enpress, the tank manufacturer, makes the following advertising claim for its popular “Vortech” brand mineral tanks for backwashing filters and water softeners:

It’s proven – we have saved over 14 billion gallons of water and counting with our Vortech® and Mid-Vortech® distributor plate technologies since they were introduced 10 years ago!

The manufacturer is, of course, basing its “proof” on the assumption that everyone who uses the tank is taking advantage of the superior backwash flow performance of the tank as compared with conventional mineral tanks with gravel underbedding. While the manufacturer’s tests show that backwashing filters built in Vortech tanks can be backwashed with up to 30% less water, it’s safe to say that only a relatively small percentage of products using Vortech tanks are actually using 30% less water as compared with similar products that use standard mineral tanks.

The reason is that Vortech tanks don’t have magic properties that makes them automatically save 30% of the backwash water. To save water, they have to be set up by the installer to have either a shorter backwash/rinse cycle or to have a more restrictive backwash flow control device installed so that fewer gallons go out the drain line. We (at Pure Water Products) use Vortech tanks on all our filters, but we take a more conservative 20% reduction in regeneration water.  (Or first concern is to make sure the filter works properly. We we want to be sure it doesn’t fail because it’s starved for water.) If everyone used Vortech tanks with our setup, therefore, Enpress would have to say that they have saved 9 billion rather than 14 billion gallons.

When I asked one of our large suppliers for their setup formula for Vortech units, I was told that they set use the same setup for Vortech as for standard tank units. Although they advertise Vortech tanks as water savers, the Vortech units they make use exactly the same amount of water as their standard units. My guess is that this is the rule rather than the exception.

High Efficiency Softener Resin

The same is true for the extra efficient softener resins. Resin that can be regenerated with 4 pounds of salt per cubic foot of resin only saves salt if the installer sets it up that way. Resin itself doesn’t automatically save salt. In fact, softeners in general are among the products that are often advertised as salt and water efficient yet are set up exactly like standard models. The most sophisticated water softener does not automatically save water if it is not set up properly at installation.

Water Saving Reverse Osmosis Membranes

High efficiency RO membranes, like the new Pentair GRO units, are great water savers and they perform as advertised.  But, they only save water if they are set up correctly. The membrane itself does not automatically save water: it has to be paired with a drain line flow restrictor that matches the membrane. It is the flow restrictor that actually governs how much water goes out the drain line, not the membrane. If you buy a GRO membrane from Amazon and put it on your RO unit, it will only save water if you pair it with a properly sized flow restrictor.

There is a new RO unit just on the market that boasts “3 gallons of drinking water to 1 gallon of concentrate.” We haven’t seen it or seen an explanation of how it works. We’ve had excellent performance from the Pentair GRO with its 1 to 1–one gallon of RO permeate water for one gallon to drain–ratio, but 3 to 1 seems to good to be true.

The Permeate Pump

The RO “Permeate Pump” is now a recognized water saver, and if you install it properly your revere osmosis unit will definitely fill its tank faster and shut off faster and therefore run less water to drain. The pump can be installed with or without a shutoff valve and there is disagreement about which way is better.  The good thing is they save water either way, and it’s easy to tell if you have it installed right: if it makes a thumping sound, you got it right.

Advanced tanks, water saving membranes, and high efficiency resins are all significant water savers, but you should not think you’re saving water just because you own them.  Most products of this type work only if  you set them up right.

Perfluoroalkyls in a nutshell

What are PFCs?

PFCs are a family of man-made compounds that are not naturally occurring in the environment. Perfluoroalkyls repel oil, grease, and water, and as a result were used as protective coatings in cookware, carpet, clothing, paper, and cardboard packaging, as well as in fire-fighting foams. They are very stable compounds that are resilient to breakdown in the environment. The most common perfluoroalkyl compounds are perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA).

PFOS and PFOA

PFOS and PFOA compounds were produced in large quantities in the United States and have contaminated air, water, and soil at locations where they were produced or used. As a result, PFOA and PFOS are found in air and dust; surface and groundwater; and soil and sediment. The highest levels of PFOS and PFOA are typically at or near a facility that produced or used the compounds. Since they are found in air and dust, they appear in remote locations where flooding and groundwater migrate them through the soil.

Health Effects of PFCs

The most common exposure to PFOS and PFOA is through ingestion, with drinking water supplies being the primary route for exposure. Typically, populations near facilities where PFOS and PFOA was manufactured or used have the highest levels of these compounds in their drinking water. Health advisories by the EPA indicate that exposure to PFOS and PFOA over certain levels may result in adverse health effects, including developmental effects to fetuses during pregnancy or to breastfed infants (e.g., low birth weight, accelerated puberty, skeletal variations), cancer (e.g., testicular, kidney), liver effects (e.g., tissue damage), immune effects (e.g., antibody production and immunity), thyroid effects and other effects (e.g., cholesterol changes). As a result the EPA has established a combined lifetime exposure of 70 parts per trillion for PFOS and PFOA.

Water Treatment?

The best and most commonly applied water treatment for PFCs in general is the old standby, granular activated carbon.

Quick Reference Table for Water Contaminant Treatment

What is DOC and How Is It Treated?

Dissolved organic carbon (DOC) is a general description of the organic material dissolved in water.

Organic carbon occurs as the result of decomposition of plant or animal material, and a small part of the organic carbon  may then dissolve into the water.

Organic material (including carbon) results from decomposition of plants or animals. Once this decomposed organic material contacts water it may partially dissolve.

DOC does not pose health risk itself but may become potentially harmful when in combination with other aspects of water. When water with high DOC is chlorinated, harmful byproducts called trihalomethanes may be produced. Trihalomethanes may have long-term effects on health. That is why DOC is a consideration when water is chlorinated.

Not only can Dissolved Organic Carbon promote the formation of trihalomethanes (THMs) in chlorinated water, it can also  interfere with the effectiveness of disinfection processes such as chlorination, ultraviolet and ozonation. DOC can also promote the growth of microorganisms by providing a food source. In addition, it can add taste, odor and color.

Organic content is usually higher in surface water than in well water.

Removal of dissolved organic carbon is more commonly done by municipalities and water suppliers than by homeowners. City water suppliers have treatment strategies to draw on that aren’t available to residential users. They are also in a better position to prevent the formation of DOC, which is usually easier than treating it.

Treatment methods effective in removing DOC from water include: coagulation/flocculation processes, biological filtration, granulated activated charcoal and distillation. For residential water treatment, GAC is the most common and the most practical treatment. Distillers can be used for drinking water only.

Usually treatment is recommended if concentrations of DOC are greater than 5 mg/L.  At that level, it is likely that chlorination will result in the formation of THMs in excess of EPA standards. Above 5 mg/L color of the finished water also becomes objectionable.  For concentrations of less than 2 mg/L, color is usually not an issue and THM creation will be small.

The best home treatment for DOC is carbon filtration.

Hard to believe, Garden Hose Day is again upon us

Moving National Garden Hose Day from August to June makes the holiday’s promoters look like geniuses.  Last year’s event, on its new June 21 date, exceeded expectations in terms of crowd sizes, enthusiasm and product sales.

Although Minneapolis has become the unofficial capitol of Garden Hose Day activities, communities large and small around the US are holding Garden Hose celebrations this year. The Garden Hose Tug, an enhanced variation of the good old fashioned Tug O’ War game, remains the main event in most Garden Hose Day celebrations, although garden hose crafts contests, in which contestants show objects they’ve created from garden hoses, are expected to run a close second in popularity at this year’s events.

Last year Cleveland added a canine division to the Garden Hose Tug. In the final round, the event winner, Little Arnold, on the left, bested Spot, his weightier opponent, in less than four minutes.

The common garden hose is one 0f life’s treasures that we take for granted.  When you think of it for what it is–a very inexpensive portable pipe that can bend around corners, roll up for storage,  and carry high volumes of water quickly over great distances–it deserves our admiration as one of civilization’s simple but awe-inspiring achievements. For simplicity, for efficiency, and for utility, the garden hose is right up there with the canoe, the bicycle and the clothes line in the list of man’s greatest creations. For gardening, car washing, filling pools–for more of our routine activities that we can recount–the humble garden hose saves time, money, and labor. But for many of us, the garden hose is of greatest importance because it evokes happy memories of childhood and summer days.

We urge you to go to a garden hose event in your neighborhood this year.

An attractive garden hose basket that is a popular item in Amazon garden hose stores. In addition to the almost limitless array of decorative hoses, there are special nozzles, colorful hose bibs, manual and electrically-powered hose dispenser/retractors,  hose splitters, hose repair kits, hose unions, hose protectors, and more.  Related items include lawn equipment, car wash paraphernalia,  clothing,  books about gardening, patio cooking, landscaping and washing cars, patio furniture, lawn sprinklers,  gardening tools–the list is endless. Yes, even X-rated products that include sex toys and clothing with suggestive phallic mottoes and pictures were on the market this year.

200 Years of Rubbish

Editor’s note:  When Lord Byron wrote almost 200 years ago that “man marks the Earth with ruin, but his control stops with the shore,” he didn’t know what deep ocean scientists would eventually find on the ocean floor, 4 kilometers below the surface in a remote spot far off the coast of Australia.  The following is from a piece by Bryan Nelson describing the finding of a  bizarre, deep sea fish without a face that has not been seen for nearly 150 years.

Aside from discovering strange and wondrous organisms, the expedition has also uncovered a monstrous reality happening at the bottom of our oceans: the amount of trash sometimes seems to outnumber the fish.

“There’s a lot of debris, even from the old steam ship days when coal was tossed overboard,” said the lead researcher. “We’ve seen PVC pipes and we’ve trawled up cans of paints. It’s quite amazing. We’re in the middle of nowhere and still the sea floor has 200 years of rubbish on it.”

The ocean’s abyssal plains are becoming our planet’s waste baskets, as toxins and dreck pile up in trenches and other low places of the sea floor. In fact, earlier this year scientists detected “extraordinary” levels of toxic pollution in the Mariana Trench, the deepest part of the world’s oceans.

It’s therefore increasingly important that researchers document the unique biodiversity of these little-studied parts of our planet to establish a baseline, so that future studies can more accurately calculate the impacts of pollution in these remote habitats.

Read the whole article (and see a picture of the faceless fish).

Water Use Doesn’t Always Conform to Conventional Logic

According to Quartz:

The word “organic” is a powerful marketing tool. In clothing—just as in food—brands love to tout their use of organic agricultural products to show they’re doing their part to fight the industry’s outsized environmental footprint. They know consumers want products they believe are better for them and the planet. “Organic,” which generally means something was grown without synthetic additives or pesticides and wasn’t genetically modified, seems to promise as much.

But the reality isn’t always so simple. Your organic cotton t-shirt may have actually used up more resources to produce than one made of conventionally grown cotton, and could have a greater overall impact on the environment.

One major reason, as various speakers pointed out at a May 23 panel held by Cotton Inc., a research group that serves the cotton industry, is that conventional cotton varieties have a higher yield, meaning a single plant will produce more fiber than its organic counterpart. That’s because conventional cotton has been genetically engineered for that purpose. In the past 35 years, cotton yields have risen 42%, largely due to biotechnology and better irrigation techniques.

Organic cotton, by definition, comes from plants that have not been genetically modified. Because of that difference, to get the same amount of fiber from an organic crop and a conventional crop, you’ll have to plant more organic plants, which means using more land. That land, of course, has to be tended and irrigated.

It will take you about 290 gallons of water to grow enough conventional, high-yield cotton to produce a t-shirt, according to Cotton Inc. To grow the same amount of organic cotton for a t-shirt, however, requires about 660 gallons of water. The disparity is similar for a pair of jeans.

Water required to grow organic cotton to make a pair of jeans is 2641 gallons as compared with 1135 gallons for conventional jeans.

More information from Quartz.

Pure Water Gazette Fair Use Statement

Leonardo da Vinci’s Understanding of Watersheds

by Emily McBroom

“In rivers, the water that you touch is the last of what has passed and the first of that which comes; so with present time.” –Leonard da Vinci.

Leonard da Vinci’s comparison of blood flowing through human arteries to the movement of water upon the Earth demonstrates his understanding of watersheds. In fact, da Vinci, along with Nicollo Machiavelli, used this knowledge of river systems to attempt a diversion of the River Arno from Pisa to Florence in the early 1500s as a military strategy. But that is another story for another time.

Da Vinci recognized that water flowed over and under the surface of the Earth in a connected, veinous pattern akin to the human anatomy. Water flows across and under an area of land to enter rivers, streams, and other water bodies to arrive at a common point. This is the description of a watershed.

Watersheds come in different shapes and sizes due to topography, geology, climate, and amount of development. For example, the Continental Divide in the United States determines which direction water will flow toward its most outward point. On the west side of the Rocky Mountains, the Colorado River flows toward the Pacific Ocean. On the eastern side, surface water flows toward the Gulf of Mexico and Atlantic Ocean. Similar to da Vinci’s connection of the human body to water flows, our own understanding of watersheds tells us much about local water sources and quality.

Another way to think of a watershed is as a big bowl separated from other watersheds by ridges or elevation directing water runoff in a certain direction. Our water supply is located in one or more of those watershed bowls. The quality of the water we receive from either wells or utility companies is determined by the runoff of water within our watershed.

There are 78 major watersheds in the lower 48 states of the US of which the Mississippi drainage basin is the largest. It is also the third largest in the world after the Amazon in South America and the Congo in Africa. On a local scale, however, there are many smaller watersheds contained within the major ones.

Why do we care about watersheds?

The United States Geological Survey (USGS) provides an interactive map for locating your watershed.