Bacteria Reduction

Filters can be a good place for bacteria to grow because there is plenty of water present, filters are dark and warm, and bacteria can feed on the organics present. While most of these bacteria do not pose a health hazard, they can cause problems for drinking water and filters:

Bacteria released into filtered water can affect taste, odor and appearance.
Downstream biofilm buildup and fouling can decrease a filter’s effectiveness by reducing absorption and causing premature clogging, thus shortening the life of the filter.

As bacteria reproduce and accumulate within a filter, they create what is called biofilm. Biofilm is a slime growth that accumulates on the filter membrane. The addition of a bacteriostat creates an environment where bacteria cannot grow. A bacteriostat is a compound of naturally-occurring silver bonded to a ceramic material that is completely inert. Bacteriostats are safe and proven:

Based on naturally-occurring silver.
Confirmed effective on many types of bacteria, yeast, fungi and mold.
Harmless to humans. Less toxic than table salt.
Offer broad regulatory approvals: NSF, EPA, FDA, Europe Biocidal Products Directive 98/88/EC, and the European Food Safety Agency.

Through a controlled release of low levels of silver, the bacteriostat's silver ions attack multiple targets in the microbe to prevent it from growing to a destructive population. This tri-modal action fights cell growth in three ways:

Prevents respiration by inhibiting transport functions in the cell wall.
Inhibits cell division (reproduction).
Disrupts cell metabolism.

Pentair Everpure Micro-Pure® II media plus bacteriostat set a new standard for water quality and addresses a growing public concern:

Reduces chlorine, particulates, asbestos fibers and cysts* in water.
Safe and effective antimicrobial protection for enhanced filtration – biofilm can’t grow and won’t coat the absorptive surface which would inhibit its performance.
Enhanced filter performance – greater available surface for the filter to use during its lifetime, and promotes a longer useful life.

Certified to NSF/ANSI Standard 53 for Cyst Reduction*, Asbestos Reduction, and Turbidity Reduction.
Certified to NSF Standard 42 – Mechanical: Particulate Reduction, Class I; Taste & Odor Reduction, and Taste & Odor Reduction.

Bacteriostatic Protection

What does Bacteriostatic mean in a water filtration context? Bacteriostatic filters do not kill bacteria, per say, but do inhibit the growth of bacteria within the filter*. In other words, the term Bacteriostatic means that the quantity of bacteria passing through the filtration system will remain static, i.e. bacteria will not multiply.



How do we achieve Bacteriostatic claims in Pentair Everpure filters? We use silver, a naturally occurring element that is highly effective for this purpose. Silver is known for its antimicrobial properties, is effective in fighting a wide range of microbes, and is preferred over other antimicrobials that are chlorine-, ammonia- or alcohol-based. Silver has been proven safe and non-toxic to people, animals and plants.

Pentair employs a proprietary technology to embed microscopic particles of silver in our bacteriostatic filter media. This filter media contains silver ions which attack microbes and inhibit their growth within the filter media of the water system, and also reduces off-tastes, odors and chlorine.

Chloramines Reduction

Chloramines are very common drinking water contaminants, and everybody is familiar with the foul taste & odor they create—at least from swimming pools, if not from drinking water. Usually their presence is not intended, but about 25% of the largest public water supplies in the U.S. add the simplest one, mono-chloramine, to the water on purpose. They use chloramine instead of chlorine because it is more stable in water, allowing for disinfection over longer distances.

About ChloraminesChloramines are a family of disinfection by-products (DBPs), formed from the reaction of disinfectant chlorine with the nitrogen atom (N) in ammonia (NH3) or organic compounds containing a reactive nitrogen atom. There are many such biological chemicals in drinking water, mostly derived from the cellular debris from killed bacteria and algae. Mono-chloramine is the simplest and most common member of the group, often produced intentionally from the reaction of pure chlorine and pure ammonia.

Chloramines in general are undesirable in drinking water because they are toxic and because they smell and taste bad. However, mono-chloramine is tolerated because it is useful as a secondary disinfectant, and it is the least toxic and smelly of the group. Still, concentrations above 4.0 mg/L are prohibited. The usefulness of monochloramine comes from its comparative weakness as an oxidizing agent: it retains about 5% of free chlorine’s chemical power, which is not strong enough to use as a primary disinfectant, but it is still able to inhibit the re-growth of any survivors of disinfection. It is also too weak to corrode copper and brass plumbing materials, and therefore it lasts much longer in the mains—two or three days instead of just a few hours for free chlorine. Finally, monochloramine is chemically too weak to produce the other common disinfection byproducts—trihalomethanes (THMs), haloacetic acids (HAAs) and haloketones (HKs),, which may pose a health hazard.

Typically water utility companies use free chlorine (or chlorine dioxide or ozone) only in the early steps of water treatment. Then, at the end, just as the finished, treated water is about to leave the plant and go out into the water mains, pure ammonia is added to convert the free chlorine residual into chloramine. Without that final adjustment, the free chlorine would continue to produce unwanted THMs, etc. for several more hours and then be completely gone, leaving the system with no continuing protection.

Standard water treatment practice is to use ½ - 1 ppm of free chlorine or 1 – 2 ppm of monochloramine. Some systems attempt to counteract monochloramine’s weakness by using more of it, but all that does is increase the frequency of taste & odor complaints. There is not much difference between the smell of the two at low concentrations, but above 1 ppm the stink of monochloramine is very objectionable—much worse than free chlorine—and removing it is even more important than removing ordinary free chlorine, especially if the water is to be used for commercial food/beverage service.

Unfortunately, chloramine is more difficult to remove than plain free chlorine: it reacts only weakly and slowly with activated carbon, just like it does with everything else. That means that the water must stay in contact with the carbon much longer than if free chlorine alone was present. Many filters do not have enough carbon for the long contact time required to achieve removal. Only products with significant capacity will give satisfactory performance.

Chlorine Taste & Odor Reduction

Chlorine is a disinfectant, most commonly used to kill microbes in the water supply. If excessive amounts are used or high concentrations reside in pipes and plumbing, chlorine can impart an undesirable taste and odor in your drinking water and other beverages. It can also contribute to foodservice equipment problems such as pitting and corrosion.

Chlorine is a very common, naturally occurring chemical element manufactured from sodium chloride. It is widely used for everything from creating household bleach to manufacturing computer chips to disinfection of swimming pools. Most water utility companies add chlorine gas to raw water to kill bacteria and other harmful microorganisms to prevent waterborne diseases. While necessary for safe water, chlorine creates many problems for foodservice operations:

Chlorine gas has a very strong, pungent smell and an unpleasant taste. It is detectable in concentrations of as low as 1 part per million (ppm).
Chlorine is an oxidizing agent, and is corrosive on metals in plumbing and foodservice equipment.
Chlorine can cause damage to gaskets in equipment, making them brittle.
Chlorine reacts with natural organic compounds in the water to form potentially harmful chemical by-products such as trihalomethanes (THMs).
Chlorine is not very effective at killing cysts, which are living organisms that can cause illness. Examples of cysts include Giardia and Cryptosporidium.

Fortunately, chlorine is not difficult to remove from water. Carbon, found in many water filters, has remarkable capacity for neutralizing chlorine. Activated carbon is a mild reducing agent and chlorine is a strong oxidizing agent, so after chlorine becomes adsorbed, it then actually reacts with the carbon. The chlorine is reduced to chloride ion (as in table salt and sea water), one atom of carbon is oxidized to carbon dioxide, and both are released to the solution (desorbed). Meanwhile, most of the spots on the activated carbon, where all this took place, become “auto-regenerated” back to their original, like new condition, ready to adsorb again. For free available chlorine (FAC), this takes only about fifteen minutes, which means that a small amount of carbon can achieve an acceptable steady-state condition if the flow rate is slow or intermittent. For “combined chlorine” (chloramines), the reaction is much slower, and more carbon or more contact time is needed to achieve equivalent reductions.   

Cyst Reduction

Several types of protozoan parasites infect people through ingestion of contaminated water containing their infectious forms, called “cysts” or “oocysts” (pronounced oh-oh-sists). Cysts and oocysts are tiny packets of two to four immature forms contained in tough, leathery shells, which protect them from drying out. They form in the intestines of infected people or animals and pass out the feces. They are extremely common, being found in virtually all surface water sources used for public water supplies. Unfortunately, their shell also protects them from the action of the disinfectants used by waterworks to purify drinking water, and they are so small that many municipal filtration systems are unable to remove them reliably. Therefore, to be completely safe, contaminated water supplies must either be boiled for one minute or fine-filtered at the point of use.

The most notorious protozoan parasites are:
Entamoeba histolytica, 10-20 um cysts, cause of “amoebic dysentery”.
Giardia lamblia, 8-16 um cysts, cause of “giardiasis”.
Cryptosporidium parvum, 4-7 um oocysts, cause of “cryptosporidiosis”.

These protozoan parasites are unusually efficient at causing infections—most bacteria and viruses require hundreds or thousands of them to evade the body’s defenses, but consuming as few as one of two cysts or oocysts is likely to lead to illness. The illnesses they cause are generally just a few days of diarrhea, cramps, nausea, etc. for most healthy people, but individuals with AIDS or HIV, cancer patients on chemotherapy, organ transplant patients on immune system therapy, and many infants and the elderly are more susceptible to long-term, life threatening disease. In some communities it is estimated that as much as 25% of the population may belong to endangered groups. Therefore, the efficiency of the fine-filtration used to remove them is of paramount importance.

There are no official point-of-use filtration standards, but public health officials have approved systems and products which demonstrate 3-log or 99.9% efficiency for filtration of either live cysts/oocysts or test particles with a diameter of 1 um (micro-meter, or micron). Also, NSF International, a third party certifying agency, has produced a voluntary filtration performance standard (Standard 53: Drinking Water Treatment Units—Health Effects) which has been accepted by most public health officials. NSF Std. 53 requires demonstrating at least 99.95% reduction of live cysts/oocysts, or alternately, at least 99.95% of test particles in the 3-4 um size range. That is about half the size of Cryptosporidium oocysts, which are the smallest of these parasites.

Pentair Everpure® precoat carbon filters are efficient fine-filters capable of removing these cysts/oocysts by mechanical means*. They have been tested and Certified by NSF International to ANSI/NSF Standards 42 and 53 for more than 99.9% reduction of particles 0.5 to 1.0 um in size in the general filtration test, and for more than 99.99% reduction of 3-4 um particles in the Cyst Reduction test. Therefore, concerned individuals and businesses may use their water after filtration through these filters, even in the face of a “boil water order” or other notification of the presence of cysts/oocysts, but only if it is confirmed that the water is believed to be potable in all other respects.

Deliming

Deliming is an acid cleaning process that removes mineral scale. This process is harsh to the equipment surfaces and, over time, shortens equipment life. It is also a costly process. Operators may need to delime equipment 3-4 (or more) times per year, and it can take a service technician from 2-6 hours to complete the process each time.

However, ignoring damaging scale buildup in water using equipment such as steam ovens or ice machines is not a viable option. It reduce energy efficiency, contributes to downtime, and increases service and maintenance costs.

The right filtration solution, one with scale inhibition or reduction capabilities, can help control scale, protecting your equipment investment and reducing the need for frequent, costly delimings.

Flushing / Sanitizing

Sanitizing is the process of reducing the number of microorganisms that are on a properly cleaned surface to a safe level. A safe level is defined as a 99.999% reduction of the number of disease microorganisms that are of public health importance.
Dilute mixtures of chlorine bleach and water or chemical agents designed specifically for this type of cleaning are common and cost-effective methods for sanitizing equipment in food processing operations. When used properly, they can be a very effective methods of killing microorganisms. However, an operator needs some type device to introduce the sanitization chemicals into the equipment.
The Pentair Everpure® JT Cartridge is the preferred way to introduce its popular ScaleKleen® Scale Remover or other sanitizing agents such as bleach into water-using appliances through an existing Everpure filter head.Flushing/Sanitizing
Sanitizing is the process of reducing the number of microorganisms that are on a properly cleaned surface to a safe level. A safe level is defined as a 99.999% reduction of the number of disease microorganisms that are of public health importance.
Dilute mixtures of chlorine bleach and water or chemical agents designed specifically for this type of cleaning are common and cost-effective methods for sanitizing equipment in food processing operations. When used properly, they can be a very effective methods of killing microorganisms. However, an operator needs some type device to introduce the sanitization chemicals into the equipment.
The Pentair Everpure® JT Cartridge is the preferred way to introduce its popular ScaleKleen® Scale Remover or other sanitizing agents such as bleach into water-using appliances through an existing Everpure filter head.

Hardness Reduction

The seven key minerals that make up most rock formations in the United States are divided into two groups: cation and anions. Cations are positively charged minerals and include calcium, magnesium, sodium and potassium. Anions are negatively charged minerals and include carbonates, sulfates, and chlorides. Each type of rock has an equal number of cations and anions, and so does each water supply.
When we discuss “hard water” we are referring to a water supply with a concentration of the four hard minerals: calcium, magnesium, carbonate, and sulfate. These minerals are components of the hard rock formations that we call lime shale and gypsum.
Mineral deposits such as limescale create major problems for food service operations that use ice, coffee, espresso, steam and warewashing equipment. Mineral scale can clog tubing and small orifices, coat heating and cooling elements, and result in increased detergent usage. Scale also causes reduced energy transfer and efficiency loss, resulting in increased energy demands for cooling or heating, and increased operating costs. Increased operating costs include the need for deliming — an acid cleaning process that removes mineral scale. This process is harsh to the equipment surfaces and decreases equipment life.

Hard water with a high pH can be treated with a water softening system or a reverse osmosis system.

Hard minerals such as calcium and magnesium, when evaporated from water or combined with heat, can form hard, chalky deposits known as limescale. These deposits can clog pipes, reducing flow, and coat heating elements, requiring more energy to heat water. Your operation loses efficiency, and your maintenance and energy costs rise.

There are different means of treating scale, such as phosphates, reverse osmosis and softening. Each treats for scale differently, for example phosphates keep mineral suspended in solution, reverse osmosis removes mineral, and softening exchanges hard mineral for soft mineral (such as sodium). Softening provides both advantages and disadvantages. An advantage is a maintained softener can provide hardness removal for many years and models can handle high volumes of water. A disadvantage is sodium must be added to the brine tank on a regular basis.

Measuring Grains of Hardness Hardness of water is measured in grains per gallon (GPG) or sometimes in parts per million (PPM). One GPG equals 17.1 ppm (Mg/l). Generally water with GPG of 7 or more is considered hard. To determine the hardness of your water, it can be tested using simple test strips or a titration drop test.
Pentair Everpure® can provide an analysis of your water to determine the correct water treatment solution for your operation.

 Water               Grains / Gallon   Mg / l or ppm 
Soft                          < 1.0                    0 - 17.1 
Slightly Hard             1.0 - 3.5            17.1 - 60 
Moderately Hard        3.5 - 7.0              60 - 120 
Hard                        7.0 - 10.5           120 - 180 
Very Hard                  > 10.5                 180 + 

High Capacity

Foodservice operations are using more water today than ever before. A myriad of industry trends are driving that increased water demand and the resulting need for higher capacity water filtration systems including, but not limited to:

Foodservice Operators (FSO) are adding equipment and expanding beverage menus, requiring larger capacities and higher flow rates than ever before.
FSOs want one-year intervals between cartridge change-outs.
Beverage and prototype store trends indicate that future restaurant, grocery and convenience store water demands will only continue to increase.
Space is at a premium today, thus FSOs would like to run multiple pieces of water-using equipment off of a single filtration system if possible.

Pentair offers a range of Everpure Filtration System solutions that deliver capacities up to 200,000 gallons (757,082 litres) and flow rates up to 15 gpm (56.8 Lpm).

Lead Reduction

Why Is Lead a Health Concern?
Lead is a toxic material, known to be harmful to human health if ingested or inhaled. Lead in the body can damage the brain, kidneys, nervous system and red blood cells. Children, infants, pregnant women and their unborn children are especially vulnerable to lead. In children, lead has been associated with impaired mental and physical development, as well as hearing problems. The harmful effects of lead in the body can be subtle and may occur without any obvious signs of lead poisoning.

How Does Lead Get into Drinking Water?Lead generally enters drinking water from a building’s plumbing system. Lead may be present in various parts of the plumbing system (such as lead solder, brass fixtures, and lead pipes) and is picked up by the water passing through the plumbing system. The amount of lead, if any, in a plumbing system will depend on the materials from which the system was constructed. Even new plumbing fixtures can leach lead into the drinking water. The amount of contact time between water and any lead source is the greatest contributing factor to lead in drinking water. The longer water remains standing in the plumbing system, the more lead it can absorb from any lead sources present. For this reason, the lead concentration is at its highest when water has remained unused overnight or over a weekend.  Additionally, factors such as water chemistry and temperature can affect the rate at which water absorbs lead.

How Do I Know If My Tap Water Is Contaminated With Lead?The only way to know whether your tap water contains lead is to have it tested. You cannot see, taste, or smell lead in drinking water. Therefore, you must ask your water provider whether your water has lead in it. For operations served by public water systems, data on lead in tap water may be available on the Internet from your local water authority. If your water provider does not post this information, you should call and find out.

What Can I Do To Reduce Lead In My Tap Water?If your tap water contains lead at levels exceeding EPA’s action level of 15 ppb, you should take action to minimize exposure to the lead in the water. Installing a lead-reducing water filtration system is one alternative to help address the problem and protect your business and its customers.

Low Mineral Content

Water hardness and temporary hardness (alkalinity), the limescale-forming portion of total water hardness, have the highest share of total minerals in most commonly available potable water. The healthiest, great-tasting drinking water and beverage ingredient water requires a specific and balanced mineral composition.
For specialty coffee, it is important to maintain some specific minerals and to balance the alkalinity level in the water for proper extraction of the coffee bean and grind, and the fullest coffee flavors. An unbalanced level of alkalinity can lead to a superficial acidity, which leads to poor crema, weak and/or bitter flavor, and a less than expected coffee aroma.
Low mineral content also has other impacts:
Tea shows more distinctive taste and less cloudiness.
Fountain beverages have consistent flavor and fizz.
Ice cubes are crystal clear every time.
Too little or too much calcium or magnesium will have an adverse impact on drink quality and lead to damaging scale buildup in water-using machines.
Pentair offers a range of solutions in this area, from its Everpure® Claris™ platform with adjustable hardness control, to reverse osmosis systems that allow you to set a blend of filtered and RO water to meet your desired water recipe.

Low Water Pressure

As foodservice establishments expand their beverage offerings, the resulting increased water usage can adversely impact operational performance. This, coupled with fluctuating city water flow and pressure, can lead to inconsistent drink quality, poor beverage dispenser performance and premature exhaustion of water filter cartridges.

Water filtration systems have minimum water pressure requirements. Keep in mind that if water pressure is too low, filters will plug prematurely because particulates collect only on the surface of the carbon and will essentially “cake” itself, instead of penetrating deep into the cartridge. It’s important to always put a carbon water filtration system after the water boost to help keep:
High water pressure flowing to the filter system, which extends the life of the cartridges.
Chlorine in the bladder of the water boost to prevent growth of algae and bacteria.

Particulate Reduction

Particulate reduction is achieved using mechanical filtration, the process of removing or separating suspended solids from the water. Sediment prefilters are an example of a common, particulate-reducing mechanical filter. Most foodservice prefilters have a micron rating ranging from 5 microns up to 50 microns, and are designed to remove larger particles. These are placed before other filtration systems to extend their life.

In simple terms, a mechanical filter is a barrier with a large number of tiny holes. The mixture of water and solids is pushed through the barrier by water pressure and any solid particles larger than the holes are trapped. The size of these “holes” determines the micron rating. A micron is the measurement used to describe the physical size of solid particles in any water supply. As a point of reference, one micron equals approximately 1/25,000 of an inch, and solid particles that measure less than one micron in size are occasionally referred to a “colloidal,” or sub-micron, particles.

The majority of mechanical filter products use simple, flow-through designs with Nominal Micron Ratings. Nominal means that approximately 85% of particles the size of the micron rating will be blocked by the filter. A few product designs are available with extremely high levels of particle reduction at small micron ratings. Most of these products were developed for consumer drinking water and foodservice applications, and usually carry one of the NSF / ANSI Standard 53 certifications for the reduction of cysts, turbidity, or asbestos fibers. Three features of mechanical filters need to be considered: the micron rating, the flow rate requirements for a mechanical filter product, and the total capacity of the mechanical filter.

Prefiltration

Prefiltration involves the use of a filter designed to remove particulate matter (dirt, sediment, etc.) from water prior to further treatment. Prefiltration is important for two reasons. First, larger particulate matter has the potential to clog or prematurely exhaust the filter(s) which follow it  in the system. Second, the effectiveness of further treatments (e.g. chemical or mechanical) can be significantly reduced in the presence of particulate matter.
A variety of prefilter types are available. The most important way in which these filter types differ is in their “fineness”, or the size of the smallest particle they are able to filter out. Water filter fineness is typically expressed in micron size. “Micron” refers to the filter pore diameter in micrometres (µm).
Ultimately, the fineness of the prefilter required for a particular application will vary, and will depend upon the quality of the source water involved (which will help identify the size of particles present in the water that need to be removed). Multiple levels of filtration are often required – prefiltration before fine filtration, for example – as much larger particles must be filtered out before water reaches the filter intended for finer particles. Without prefiltration, these large particles may damage the finer filter(s).
It is also important to choose the correct size of filter. The “size” of the filter refers to the maximum flow rate that it is able to accommodate. There are often multiple filter sizes available for each level of fineness. The water pressure of the system must also be taken into consideration. Each filter model will have a limit to the maximum pressure at which it can operate. Also, the filter’s minimum operating pressure should be noted to ensure this pressure will be maintained to optimize system performance.
Deciding whether to add another level of filtration is a cost/benefit decision. While any form of prefiltration requires extra cost, the operator must take into consideration the costs or losses that would be incurred without prefiltration. Prolonging the life of more expensive downstream fine filters, for example, may be well worth the investment.

Reverse Osmosis (RO)

What is it and how does it work?
Science class taught us that osmosis is a natural process by which water and nutrients are supplied to living cells. The cell membrane is a natural, semi-permeable membrane, meaning only selected materials can pass through, and others cannot. An osmotic membrane allows only water to pass through easily, while restricting the passage of all kinds of contaminants. If such a membrane separates two water solutions with different concentrations, osmosis will cause water to move from the diluted solution into the more concentrated solution, as if to dilute it.
In reverse osmosis, the opposite occurs. Pressure is applied to the solution with a higher solids concentration to cause the flow of liquid to reverse (from concentrate to permeate), unlike natural osmosis. The synthetically-produced membrane allows only the water molecules with very few other molecules to pass through into a storage tank for future use. The remaining source water, containing a higher percentage of contaminants, is left to waste. The process, known as ion exclusion, occurs when ions, or charged atoms, form a barrier at the membrane surface to reject contaminants. With an RO system, it can be said that water is removed from the minerals, unlike traditional systems in which minerals are removed from water.
Because Total Dissolved Solids (TDS) cannot be removed with mechanical filtration or standard carbon filtration, a Reverse Osmosis system is one of the most effective means of filtration. With an RO system the TDS level increases on the high pressure side of the membrane as water permeates through the membrane to the low pressure side. The high TDS water is flushed down the drain, and the water that has passed through the membrane now has very little TDS and is available for immediate use.
Semi-permeable membranes are critical for reverse osmosis to be effective. Today, the most common artificial membranes are made from cellulose acetate, cellulose triacetate or aromatic polyamide resins. These membranes are tough enough to sustain the higher water pressures needed for maximum contaminant removal efficiency. Unlike ion exchange systems that need to be regenerated often, the average RO membrane can last two or three years before replacement.

When is Reverse Osmosis Applied?In foodservice applications, there are a few specific reasons that Reverse Osmosis may be applied. RO should be considered if the TDS content in the water is high enough to:
Impart objectionable taste.
Cause scale buildup in equipment.
Cause poor quality of beverages and ice, such as weak carbonation or soft ice.
The U.S. Environmental Protection Agency (U.S. EPA) sets a secondary standard of 500 mg/l TDS in drinking water. Secondary standards are recommended guidelines for contaminants that may cause cosmetic or aesthetic effects in drinking water. Different foodservice applications require different levels of TDS. Steam applications require water with very low TDS to prevent heavy scale accumulation that could damage or destroy the equipment, while fountain beverage applications are fine with TDS of up to 500 ppm because scale typically does not pose a problem since there is no energy being applied to the water. Some Everpure RO systems provide a “blend” feature that allows raw water to bypass the RO membrane. Both the raw water and the RO water are filtered through a traditional taste & odor filter and then blended. This control of the quantity of TDS allows the system to meet specific water specifications. For example, a coffee recipe may require water with a TDS of 150 ppm.

The Benefits of Reverse OsmosisReverse Osmosis is extremely effective at eliminating or substantially reducing a wide variety of contaminants, more than most all other types of treatment. Because Reverse Osmosis removes from 95%-99% of the total dissolved solids, it is often the best technology for obtaining clean water that is free of TDS and other contaminants. And because it is stripping water of damaging contaminants that can cause harm to equipment, it helps reduce operating costs.
RO systems are effective in removing excess salt and other dissolved minerals, taste and odor, heavy metals, microorganisms, nitrates and pesticides. Water treated by reverse osmosis has a noticeably cleaner and sparkling appearance and allows subtle flavors in foods and water-based beverages to come through.

The Drawbacks of Reverse OsmosisDespite their effectiveness, RO membranes are subject to a number of factors that make them susceptible to loss of function. The amount of contaminants, size and type of equipment, and system pressure all can contribute to buildup of material on the membrane. In addition, disinfectant chlorine can attack some membranes. To prevent this, RO systems typically include a carbon prefilter to reduce chlorine that can damage the membrane. A sediment prefilter also is used to prevent fine suspended particles in the source water from permanently clogging the membrane. Larger commercial systems sometimes soften the incoming water or add scale inhibitors to preserve membrane porosity.
Reverse Osmosis systems are also more expensive than traditional filtration, and require more maintenance. And, because a portion of the water supply must be used to flush the contaminants to drain, there is a waste factor that can represent a significant portion of the total water use. Another drawback to Reverse Osmosis is it produces clean water at a slow rate, and therefore requires the use of a holding tank so water is available during peak usage periods.

Scale Reduction

What is Scale?
As rainfall descends, it picks up CO2, which makes water slightly acidic. By the time it reaches the earth, it is now a natural solvent. As it seeps down to the underground aquifers, it dissolves mineral along the way, becoming “hard.” Hard water is generally concentrated with four hard minerals: calcium, magnesium, carbonate, and sulfate. Every water supply has some dissolved mineral content.

How Does Scale Form?When energy is applied to hard water, the minerals can drop out of the solution and settle on surfaces. This is called scale, the most common of which is limescale. These minerals can form a hard crust that can cause many problems with equipment, from clogging to increased energy requirements.
To understand the process that allows dissolved mineral content to rebuild solid rock, it is important to understand the condition of pH. The scale for pH is measured from 0.0 to 14.0, with 7.0 as a perfect neutral. In general terms, water supplies with a pH below 7.0 have a greater acid content and tend to dissolve rock into minerals. Water supplies with a pH above 7.0 have a lower acid content and tend to build mineral scale.
There are two key conditions for scale formation:
The pH level must be neutral or above
There must be an energy transfer, cooling or heating, to act as a catalyst.

How Does Scale Affect Water-using Equipment?Mineral deposits such as limescale create major problems for foodservice operators with ice, coffee, espresso, steam and warewashing equipment. Mineral scale can clog tubing and small orifices, coat heating and cooling elements, and result in increased detergent usage. Scale also causes reduced energy transfer and efficiency loss, resulting in increased energy demands for cooling or heating, and increased operating costs.
Many water-using appliances, from coffee brewers to ice makers, are susceptible to limescale build-up. Steamers and combi ovens are among the most susceptible. As water boils and evaporates, minerals remain and become concentrated. Because of these high concentrations, steamers can require frequent deliming—an acid cleaning process that removes mineral scale. This process is harsh to the equipment surfaces and decreases equipment life.
Freezing water can also cause scale to form. Commercial cuber-type ice makers require more service to correct scale build-up than any other equipment commonly used in foodservice. Like steamers, commercial icemakers leave a high concentration of minerals as most of the water becomes ice. The resulting residue is a murky mixture full of sediment and growing crystals that restricts tubes, fouls pumps, clogs orifices, scores valves, and causes ice to hang in clumps.
Fortunately, scale growth can be reduced by adding small amounts of polyphosphates to water. Polyphosphates are completely safe and nontoxic, and many occur naturally in foods or are added during processing. They are also used in the treatment of drinking water to combat corrosion and scaling. Most scale-producing situations can be resolved more effectively with a point-of-use water treatment system that couples fine filtration and a polyphosphate feed. Fine filtration reduces particles that act as nucleation sites for scale formation. These particles speed up the scaling process and can add as much as 60 percent to the weight of the scale, depending on the particles in the source water. Everpure produces many systems meeting these specifications for home use, vending and office applications, and commercial foodservice.

Types of ScaleThe appearance of scale varies infinitely and depends on the impurities that are present in the water. For example, pure limescale is pure white, but sediment and turbidity due to dust, dirt and mud may color it.

Treating ScaleThe most common methods for reducing scale are:
Polyphosphates
Reverse Osmosis
Softening