The Real Cost of Washing Dishes
by Tom Stroozas – CFSP, RCGC, CFE
Manager – Commercial Marketing Piedmont Natural Gas

In some of my previous articles we’ve discussed cooking equipment performance and how to select the best equipment for your foodservice operation. Now we’ll go to the very back-of-the-house and investigate the ins and outs of an often taken for granted but most critical step when it comes to serving your product to your customers – your warewashing process.

Making the Case for Sanitation

Cleanliness is the top priority for foodservice customers. As an operator, you may think that food quality and service is what keeps your customers coming back, but think again. If you aren’t serving your product on sparkling clean and bacteria free dishes, they won’t be coming back for long. A recent study by the Food Safety Council shows that less than 50% of customers think restaurants are doing a good job ensuring safe food practices. With that in mind, the timing could not be better for the industry to prove itself to the public with proper food safety practices. A key component of this commitment is properly cleaned and sanitized dishes and utensils.

While no foodborne illnesses are documented to have come from food served on unclean dishware, foodservice safety inspectors openly admit that improperly cleaned and sanitized utensils do increase the risk of foodborne illness outbreaks.

The real issue here is cross-contamination. If, for example, a knife has been used to cut raw poultry and is not properly cleaned and sanitized, it provides an excellent environment for breeding bacteria. That, in turn, can contaminate the next food it’s used on. Proper cleaning and sanitizing of utensils can easily eliminate this problem.

When it comes to food safety, it’s imperative that the dish room staff, no matter how high the turnover, be properly trained in dish machine maintenance. Operating temperatures that are too low, clogged rinse arms and poor water pressure can leave your operation with unclean and unsanitized dishes. Many local health department officials have commented that often 50% of the machines they look at in a given day of routine inspections fall short of functioning properly!

Operators should give the employees the responsibility to verify that the dish machine is working properly and teach them routine maintenance procedures. Even more importantly, tell them whom to call for local professional service. Keep in mind, if your dish machine is down, you’re out of business! Those who do not realize this and continue to operate are setting themselves up for a potential major liability!

The Impact of Time and Temperature

In order to consistently reach the required heating level and exceed it during the sanitation process, operators are increasingly turning to high-temperature warewashing equipment that heats the rinse water to 180°F. At this temperature, cleaning and sterilizing are more complete and final drying time is reduced. To reach this temperature, machines require booster heaters that can efficiently and economically provide the temperature boost required.

The booster heater literally boosts the temperature coming into the warewasher from the water heater from 140°F to 180°F for use as a final sanitizing rinse. The higher temperature offers many advantages in addition to leaving dishes, glasses and utensils sparkling clean and bacteria free!

High-temperature machines save on water and detergent in that the fresh, final rinse water circulates to preheat the next load’s wash water. Generally, low temperature (chemical) rinse machines have a much longer wash cycle and incorporate a fill and dump rinse approach for each load, thereby using more water and detergent than high-temperature systems. And of course, more water means higher sewage costs, too.

The sanitizer/rinse water mix used in low-temp systems ranges in temperature from 115°F – 140°F. Because of the lower temperatures, manufacturers suggest a thorough scraping of the dishes prior to loading. Also, products such as lipstick, meat fats, egg yolks and citrus pulp do not melt off until they reach 160°F. So dishes might not come out clean on the first run-through and often have to be rewashed. All this adds to your overall labor, energy, detergent, water and sewer costs, making low-temp systems more expensive to operate in the long term.

High-temps Outperform Low-temps

A typical high-temp rack machine will wash about 55 racks of dishes per hour, compared to 40 racks per hour in a low-temp chemical rinse unit. Because of these faster cycle times, high-temp users can wash more dishes in the same time period, thereby saving labor, energy, water, sewage and detergents. High-temp machines are really a no-brainer and it’s easy to see that they most certainly will add profits to your overall bottom line!

Dishes leaving a high-temp washer flash dry. The dishes are heated to a higher temperature during the sanitation cycle and when they come out of the washer they hit the cooler air. The sudden temperature change causes them to dry faster and virtually spot free! This decreases drying time and also diminishes the likelihood of water buildup on your washroom floor. Dry floors promote a safer environment for your employees and can reduce accidents caused from having an employee slip and fall. This statement is backed up by an OSHA study reporting that 41 cents per dollar of workman’s compensation claims in the restaurant industry are related to slips due to water on the floor. Voila, less liability from accidents and therefore less health care claims!

Competing Against Chemicals

Low-temp warewashers, which use chemicals for sanitizing, are often used in the foodservice industry because of their reasonable first cost. But they present some issues that operators need to know.

The chemical sanitizers used in low-temp machines are regulated by the Federal and State EPA, which classify them in the same category as pesticides. Labels must state concentrations, effectiveness, directions for use, and possible health hazards. Chlorine agents used in low-temp warewashers can be corrosive to the machines and plumbing over time. These chlorine compounds are also more likely to damage rubber and metals, such as pewter, stainless steel, aluminum and silverplate. You just don’t have these issues with high-temp systems!

New Innovations

A well-known rack and flight machine manufacturer now features an exclusive, patent-pending rinse technology that is being touted as the industry’s most advanced water and energy saving rinse system. The new rinse technology creates a strong and powerful spray by forming an S-shape pattern across the surface of the ware. The pattern could mean a savings of up to 50% in energy use, but more importantly up to 50% in water! And, as an added bonus, savings in rinse agents, too. It can even help operators save additional money by reducing the size of the booster heater required.

The secret behind new rinse technology is bigger drops. Because bigger water droplets transfer heat more efficiently to the ware, the result is completely sanitized and sparkling-clean dishes.

These special rinse nozzles also cut down on maintenance costs through longer life, easy replacement and use of specially formulated resin material, which is resistant to corrosion, chemicals, clogging and heat.

Hazards of Stacking Dishes Wet

Even though a low-temp chemical machine will deliver dishes that are free of bacteria, the dishes will still be wet when exiting the machine. This is where caution needs to be exercised. Those once bacteria-free plates can easily become contaminated again if they are not allowed to dry properly before being piled up after washing. A study conducted by Oregon Health Sciences University in Portland suggests that just may be the case. It was assessed whether stacking wet dishes in a commercial establishment may contribute to the growth of harmful bacteria on plate surfaces. The researchers first identified bacteria on 100 dishes (prior to washing) that had been used to serve meals to patients at a medical facility. They then put half the plates through a full cycle of a warewasher, stacking the plates after placing a small amount of water on each surface. The other 50 plates were machine washed and then left to air-dry for 24 hours.

Twenty-four hours after washing, the investigators found no apparent difference in bacterial growth between those stacked wet and those fully air-dried. However, after 48 hours a significantly higher amount of various bacteria was evident on the wet-stacked dishes. Although it was not determined exactly what kind of bacteria had grown on the plates, they conclude that there is a risk of bacterial growth and food contamination if dishes are stacked wet.

This study gives increased reasons for moving from a low-temp chemical warewashing system to a high-temp hot water sanitizer. Remember, the high-temp machine delivers flash dried dishes that may be stacked without the concern of potential bacterial growth due to stacking wet.

Bottom Line Comparison

If you’re still not convinced that high-temp is the way to go, then let’s review our findings and see the clear-cut advantages.

A high-temp machine can really pay for itself by reducing the cost of chemicals alone. An industry rule of thumb is that a high-temp machine will use approximately fifty-percent less detergent and 100% less sanitizer! When you also consider that low-temp machines often require as much as 30% rewash, this can add significant costs and have a major impact on your bottom line! Many operators who pay for their machine use on a charge per rack basis could be paying anywhere from five to seven cents per rack. When one adds up the rewash potential, the cost per rack in a low-temp machine could actually increase to over nine cents per rack.

So there you have it the real cost of washing dishes! To find out how much you can save with a high-temp system that uses one of the new gas-fired booster water heaters, give me a call at or email:

Reprinted with permission from Cooking For Profit December 2004