Foodservice Equipment Reports

SPECIAL REPORT: Water Rights

Think your water supply is safe? Think again. While your source—whether municipal or well—may provide Environmental Protection Agency-approved and safe drinking water, it could leave a bad taste in customers’ mouths (literally!) and wreak havoc on your equipment.

Water is a universal solvent; in its travels to your facilities it can pick up all sorts of contaminants, from dirt to chemicals and minerals to volatile organic compounds, or VOCs. What and how much of each depends on a whole host of factors, not least of which is the part of the country you’re in.

Most of you get water from a municipal water district whose job is not only to provide water, but also make sure it meets EPA safety standards. At a minimum, your water will be filtered to remove sediment (big stuff like twigs and rocks) and treated to kill illness-causing pathogens, usually with chlorine or chloramine (that’s chlorine with the addition of a little ammonia—yum!).

Apart fromm the safety issues, other stuff in water seriously affects <I>quality<I/>. Hardness, for example, a major component of water caused by dissolved minerals, ranges from a slightly hard 3 grains per gallon (about 60 parts per million) in Seattle to a tooth-jarring 90 grains/gal. (1,500 ppm) in West Texas. And a variety of contaminants not only vary by location, but even by time of year.

Most of our drinking water either comes from ground-water sources (rivers, lakes, snowmelt, etc.) or aquifers (underground water tables). In spring, for example, water in municipalities that source from lakes and rivers will likely have more sediment. Areas that rely on aquifers may experience harder water in summer and fall as water tables are drawn down.

The point is that the water you use in any given facility may contain stuff that affects its taste and the performance of your equipment. The stuff in that water will be different from one store to another, from one area of the country to another, and may change during the year.

Water filtration systems help you deal with all these water issues. Companies continue to improve water filtration and treatment technology, giving you a wider range of options for your specific applications. But how to choose?

Three primary reasons you should consider water filtration/treatment are product quality, product consistency and equipment protection. When you’re unsure of the source or quality of your water, a fourth reason to filter and/or treat water is safety. Most water—at least from municipal sources—is safe, but you may have stores that use well water or untreated water.

In some cases, one filter and/or treatment type will solve your water problem. In others, you may need an entire system to get the result you want.

Know Your Stuff

Knowledge, of course, is your best defense against all the things that can go wrong with your water. If you know what’s likely to be in it and what those substances can do, you have a good idea of what you’re trying to prevent. Here are some common “ingredients” in tap water:

Sediment. Dirt, including mud, twigs, small stones, organic matter and so forth, is a lot more common in water than you might think. It can affect taste and cause beverages to appear cloudy.

VOCs. Those volatile organic compounds we mentioned earlier are among the prime causes of water that tastes and smells “off.” Those odd and often repellant flavors and odors get transferred to all the beverages you make with your water, too—soda, tea, coffee, and lemonade and other juices. That transfer is a quick way to lose customers.

Chemicals. As we said, chemicals such as chlorine and chloramine are deliberately added to water to kill microorganisms and make it safe to drink. But they cause beverages to taste and smell funny, too. They’re also corrosive and can damage any equipment using water—ice machines, steamers, combi ovens, coffee and tea brewers, espresso machines, etc. Other chemicals may leach into water from various sources, too.

TDS. Water holds dissolved minerals and metals such as magnesium, calcium, zinc and iron, and other organic material in suspension. These substances are called total dissolved solids, or TDS. Water’s hardness is a measure of its TDS content. To a degree, TDS will impart taste and odor to water. Their bigger danger, however, is to equipment. Minerals, especially, can precipitate out of water and cling to equipment—what we all know more commonly as scale or “lime.”

Water also can contain alkaline substances such as bicarbonate. Water’s alkalinity determines how easily the minerals and TDS in water will form scale. When heated, for example, bicarbonate in water binds with calcium, forming calcium carbonate scale on surfaces like heating elements or the walls of boilers, steamers or combi ovens.

Most utilities can give you a report of your water’s hardness or mineral content, measured in parts per million or milligrams per liter; total dissolved solids, also expressed in ppm or mg/L; and alkalinity, shown as a measure of power of hydrogen, or pH. (A pH of 7.0 is neutral, while up to 14.0 is acidic and down to 0 is alkaline.)

Critters. Most municipal water systems use chemicals to destroy pathogens that could make your customers sick. But it’s possible that some microorganisms—cysts, bacteria and viruses—may get into your water supply, depending on where you are. Obviously, the health of your customers is the big issue here. 

Know Your Filters

There are five basic technologies used to treat water in foodservice operations. Three involve filtration, and two treat water to prevent scale formation.

Mechanical filtration. Mechanical filters remove sediment from water in much the same way your hood filters remove grease particles. Sediment includes all the rocks and twigs water collects on its journey from surface or ground water sources to your tap.

Filter makers produce two basic types: depth and surface. Depth filters capture particles throughout the filtration medium. Typically, manufacturers shape types of plastic like polypropylene into different forms for the filter media. Common designs are spun fiber, string-wound and pleated filters.

Depth filters effectively remove large particles—around 5 to 20 microns—fairly inexpensively. A good depth filter may be all you’ll need in many cases. Where water is particularly “dirty,” though, you may need to use a couple of depth filters in series or one as a pre-filter before using a surface filter.

Membrane separation. Surface filters collect sediment on the surface of the filtration medium. Usually a membrane of some type through which water is forced, surface filters capture much smaller particles—down to 0.1 micron in the case of microfilters, and as small as 0.01 micron in ultrafiltration systems. The waste is periodically flushed away from the surface of the membrane.

Reverse osmosis is the most well-known type of membrane separation filtration. R/O systems remove a broad range of TDS and other contaminants, producing essentially pure water. That has its own drawbacks, which we’ll get to in a bit.

Carbon filters. The most effective way to remove chemicals such as chlorine and chloramine and tastes and odors produced by VOCs is with activated carbon. Carbon removes impurities through adsorption—the impurities cling to the surface of the carbon—so the more surface area a carbon filter offers, the better. That might suggest granulated carbon would be most effective, but water can find channels through the granules that allow it to pass untouched.

Carbon also tends to be porous, which allows water to pass through and provides more nooks and crannies (surface area) for impurities to adhere to. Since carbon filters are mechanical filters, they can quickly clog up with sediment if you don’t have a good pre-filter or other mechanical filter in front of them.

Scale inhibitors. Inhibitor media either bind with minerals and hold them in suspension or cause them to crystallize into tiny clumps that are too big to precipitate and cling onto surfaces. In both cases, the minerals along with the media are flushed away after a cooking cycle, or are incorporated into a finished hot beverage (e.g., coffee) with no change in taste or smell.

Inexpensive polyphoshates are the most common type of scale inhibitor media. Most work really well up to about 150ºF, but they break down at higher temps and cause beverages to turn cloudy. For coffee and especially tea brewers, some polyphosphates are designed for temperatures up to about 200ºF.

Newer scale inhibitors reverse the polarity of calcium and magnesium particles, causing them to form crystals instead of clumping together. When the crystals grow to a certain size, they break away from the inhibitor media and remain in suspension. Unaffected by temperature, this type of inhibitor is ideal for high heat applications like espresso machines, or steamers and boilers that have a flush cycle.

Ion exchangers. Water softeners operate using a principle of exchanging an ion on a mineral molecule for a salt ion. Water flows through a charged resin where calcium and magnesium ions, for example, are exchanged for sodium ions. The reformed mineral molecules can’t form scale any longer, but your water will have a slightly saline taste. And softened water makes lousy coffee and carbonated beverages.

Another potential problem with ion exchange water softeners is that some municipalities have outlawed the discharge of the brine these units produce as waste. With water at a premium, water treatment plants don’t have extra water to dilute the brine enough to prevent it from harming the environment.

What To Use Where

It’s tempting to look for a single filter or system that will solve all the potential problems water poses for your operations. That might work in a coffee shop where there’s really only one application.

In most foodservice operations, though, there are lots of different applications—ice making, cooking, carbonated beverages, hot beverages, dishwashing—that require water, and each has its particular challenges.

Most operations probably can benefit from some filtration—a pre-filter to remove sediment and a carbon filter to remove chlorine and odors. After that, you’re likely better off looking at each application separately and specifying a filtration system to do the job right. Here’s a look at some common applications and possible filtration/treatment solutions to problems caused by poor water quality.

Carbonated beverages. A mechanical filter will remove dirt and sediment, which can inhibit carbonation, and a carbon filter will remove off odors and taste and chlorine. If your water is extremely hard, you may have to consider R/O since ion exchange water softeners will dramatically affect sodas’ taste.

Coffee. If you offer a standard coffee program, use a good mechanical filter and a carbon filter like one you’d use for soda, but add a heat-tolerant polyphosphate or other scale inhibitor to prevent lime buildup. If you have a specialty coffee program, you’ll likely want to go a step further to control the consistency of your water quality (and taste), and may use R/O.

Tea. Again, start with good mechanical and carbon filters. Polyphosphates can turn tea cloudy in appearance. To protect your equipment from scale, use a crystal-forming scale inhibitor instead.

Espresso. The extremely high temperatures at which espresso machines operate make them ideal breeding grounds for scale. To prevent or reduce scale without affecting taste, more and more operators are turning to R/O systems. Higher efficiency and features such as TDS monitors and blending valves on newer models make them more attractive. For better taste and to protect the R/O membrane, use a good pre-filter and carbon filter.

Cooking equipment. Steamers, combi ovens, or any other equipment where water comes in contact with heating elements are all highly susceptible to scale. But here you’re concerned only with scale formation, not taste. A heat-resistant polyphosphate or crystal-forming media will do the trick in most cases. In areas where water is extremely hard, an ion exchange softener can help, or you may decide to spec an R/O system.

Ice machines. These units present their own challenges, particularly when it comes to chlorine. In ice machines, chlorine helps prevent mold growth, but it also is corrosive and affects the taste and odor of ice (and the beverages in which the ice is used). Follow the manufacturer’s recommendation when it comes to whether or not you should use a carbon filter, but do use a good mechanical filter to remove as much dirt and sediment as possible.

Scale also can be a problem in ice machines. Most cubers are designed to cascade water over the evaporator so only pure water freezes, leaving the minerals and sediment where they can be flushed away at the end of an ice-making cycle. You may also consider using polyphosphates, if necessary.

Warewashers. High heat in warewashers can cause scale formation. The least expensive fix here: scale inhibitors such as heat-resistant polyphosphates or crystal-forming media.

Specs And Maintenance

Manufacturers can help you identify potential water problems and develop specs for filtration/treatment systems. Start by educating yourself on what the various ingredients in water can do in each application in your operation. Your local municipality can provide a report on local water quality and what’s in it. Keep in mind your goal is to maximize product quality and minimize potential damage to your equipment.

Have your water tested. Find out specifically what you’re up against in your stores. When you start to look at filters and systems, make sure they’re NSF approved. NSF-certified filters will perform as claimed by manufacturers. Key standards to be aware of are NSF 42, which applies to water aesthetics (taste, odor, appearance); NSF 53, which filters must meet to make health claims (reduction of metals like lead, cysts and VOCs); and NSF 58, which sets standards for R/O systems (including cyst and VOC reduction).

NSF also governs flow-rate claims, an area you should pay particular attention to. You’ll need to size your system appropriately for the volume you expect in each store. Flow rate is one determinant of what size system you’ll need. The other main one, if you’re using membrane separation technology (nano-filtration, ultra-filtration and R/O) is storage tank size, since these filters may not have flow rates adequate to your needs.

Don’t forget that flow rates decline as filters get full and reach their capacity. Capacity is just as important as flow rate when evaluating how filters will perform in your stores. A carbon filter may have a high capacity for chlorine and VOCs, but clog up quickly with sediment, shortening its life. Likewise, a mechanical pre-filter with low capacity will quickly affect flow rates of any other mechanical or carbon filters down the line.

That brings us to maintenance. Most systems now are designed with easy-to-change cartridge filters. Replace them when you’re supposed to (according to manufacturer recommendations) and you should have no trouble with your system. Newer models often come with indicators that let you know when filters reach capacity.

Manufacturers are making the whole process easier, designing individual components in a way that makes them easy to combine in a system that meets your specific needs. In many case now, they’re also designing in features that let you adjust the system for different water quality right on site.

R/O systems, as we mentioned, let you blend in tap water to achieve a desired water recipe. Another example is a new ion-exchange water softener that also filters water and has controls that let you blend the two. Self-contained, it’s smaller than traditional water softeners and doesn’t require a ton of salt on site.

New technology and versatile designs can help you set your water to rights no matter its quality when it comes in your stores.

Anatomy Of A Modern R/O System

You’ve probably heard a lot of buzz about reverse osmosis and wonder how much of the hype to believe. In the past R/O systems have been criticized for being expensive, wasting water and fitting only a few select applications. While there are still pros and cons to using R/O, manufacturers have overcome a lot of the negatives associated with the technology.

At its simplest, R/O is a process in which water is forced against the surface of a membrane. The water molecules pass through the membrane, leaving behind everything else, including minerals and other total dissolved solids, or TDS. The only substances the R/O process won’t remove from water are the “off” tastes and odors associated with volatile organic compounds, or VOCs.

On the plus side, because R/O removes minerals, it’s an excellent filtration choice for high-heat equipment—steamers, combi ovens, espresso machines and coffee brewers. Stripping water down to its purest form, though, turns it slightly acidic, making it “aggressive.” Essentially, it can corrode equipment. Water with no minerals also lacks character, actually detracting from the flavor of most beverages.

Not The Same Old Same Old

Over the past few years, manufacturers have designed R/O systems with blending valves that add tap water to the pure water filtered through the R/O membrane. You can dial in whatever amount of TDS you want in the water coming out of the system to create your own water recipe.

The degree of consistency provided by R/O systems is the reason several large chains use it for their coffee/espresso programs. No matter the quality of your water, nor how much it may vary from store to store, R/O systems can provide you with the same basic water throughout your operations.

Some newer models even have a TDS gauge that measures the mineral content of your water, letting you adjust your recipe as water changes with the seasons.

In the past, R/O systems also used a great deal of water. To keep the membrane clear and working properly, R/O systems would flush 3 gals. or 4 gals. down the drain for every gallon of pure water they produced. With newer membranes and better technology, that ratio has been reversed. Many R/O filters now are about 80% efficient, which means that for every 4 gals. of pure water, only 1 gal. ends up going down the drain.

While you still may think of that as a gallon of wasted water, you should consider it long-term savings. Your ice machine, steamer and some other equipment use water to flush contaminants, especially scale-forming minerals, down the drain to extend their life and improve performance. R/O systems basically do the same thing.

In fact, if you use a pre-filter to remove most sediment and a carbon filter to remove chlorine (which is very harmful to membranes), most R/O membranes will last three to five years before needing replacement.

Better Performance

Manufacturers have found different ways of making R/O systems more efficient. Some use membranes that allow the filter to work at normal incoming water pressure, around 50 psi. These non-electric models don’t require pumps (unless water pressure is too low).

Another manufacturer counteracts the backpressure from the storage tank (which causes water trying to get through the membrane to flush down the drain instead) with a dual pump system. One pump pushes water through the membrane, and another pump on the other side of the membrane pushes against the backpressure from the storage tank, allowing the pure water through.

Finally, another past concern about R/O systems was that they’re slow and require a storage tank for “finished” water. In some cases, your operation’s demands during a rush may exceed the capacity of the tank and the filter. Many newer models have a bypass valve that automatically routes pre-filtered tap water around the R/O system when your storage tank runs low.

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