TACT Spells the Formula for Clean, Sanitary Dishes

The Key to Effective Dishwashing

A problem with your dishmachine can send a ripple of trouble throughout your restaurant. Long wash cycles can leave you without dinnerware and slow down service, dishes with stuck-on debris will almost certainly leave guests dissatisfied, and improperly sanitized wares can even make your guests sick and open the door for legal trouble. Fortunately, you can avoid each of those scenarios if your warewasher is able to provide a balance of four critical factors: temperature, agitation, chemicals, and time – or TACT.

If any one of the four factors in TACT is lacking, dishes may not get adequately cleaned and sanitized. Lets take a look at each of them in depth and learn how you can make sure your dishmachine is operating with the correct balance.


Heat plays several important roles in the warewashing process. Hot water loosens and dissolves stuck-on food, melts fats, and distributes the chemicals that clean and sanitize wares. Each step in a machine's cycle requires that water be heated to a certain minimum level.

The first step in most restaurant dishwasher cycles is the wash stage. The water used in this step is typically heated to 150 degrees Fahrenheit in the machine's built-in wash tank. This stage combines that water with detergent that works to loosen and wash away debris.

More complex dishmachines often perform a scrap stage prior to their main wash stage. This stage is designed to remove the food soil that staff would ordinarily remove using a pre-rinse sprayer before sending wares to the dishmachine. During this phase, it's actually possible for water to be too hot, because intense heat can cause debris to become baked onto dishes to the point it can't be removed in the wash cycle. If you feel that your machine is having this problem, a service technician may suggest installing an aquastat that will temper incoming water to the ideal temperature for the scrap stage.

Nowhere in a warewasher's cycle is water temperature more important than during its sanitizing rinse stage, which is typically the final step in the warewashing process. As a matter of fact, every dishmachine falls into one of two categories depending on the temperature of the water used during this cycle.

High-temperature commercial dishwashers sanitize wares using water heated to at least 180 degrees Fahrenheit to kill bacteria that may persist on the dishes after the wash cycle. Those high temperatures are reached by running incoming water through a booster heater, a gas- or electricity-powered component that may be built into the dishmachine or sold separately, depending on the model of machine that you choose.

Booster heaters are designed to give rinse water a 40- or 70-degree-Fahrenheit rise in temperature. If you're shopping for a new booster heater for your restaurant dishwasher, it's critical that you choose one that will raise water from your building's hot water supply to the 180 degrees Fahrenheit temperature it takes to sanitize dishes. For example, if your building's water supply measures 110 degrees Fahrenheit, you'll need a 70-degree booster to raise water to the adequate temperature.

The alternative to the high-temp rinse method is the low-temp method. At least in the case of commercial dishmachines, "low-temperature" doesn’t mean cold. Low-temp machines' rinse cycles still use water from your building's hot water supply, the temperature of which will probably average around 120 degrees Fahrenheit. That temperature isn't hot enough to kill bacteria on its own, so low-temp machines combine rinse water with chemicals to provide sanitization.

If you feel that inadequate temperatures are causing a problem for your warewasher, the first thing you should check is the temperature of your building's hot water supply. Check it at your dishmachine's inlet if possible. If that inlet is not accessible, check the temperature at the closest source to the dishmachine. The key is to check the temperature during your building's busiest period of the day. That's when demand for hot water will be the greatest and you'll run the highest risk of running out of an adequate supply of hot water.

Verify that the hot water meets the minimum temperature requirements listed in your dishwasher's manual. If temperatures are lower than that spec, you may need to invest in a supplementary water heater. Temperature test strips will help you check whether your machine is reaching the adequate rinse temperature.


The second factor in TACT is agitation, which is created by the physical motion of water as it impinges on plates, working to loosen stuck-on food debris. That water is distributed via the wash arms, which are either stationary or spinning, depending on the type of commercial dishwasher in question.

Clogged wash arms are often the culprit behind poor dishmachine agitation. Over time, the individual holes that distribute wash water can become clogged with debris and blocked, so water isn't distributed how the manufacturer intended for it to be. For this reason, most manufacturers now build their equipment with removable wash arms that can easily be cleared of debris and kept washing efficiently.

Another factor that can lead to sub-standard agitation is low water pressure. Manufacturers design their machines to operate at a certain incoming water pressure. If the pressure falls below that point, the machine may not be able to dispense water with enough force to remove debris from dishes. Low water pressure can be caused by a number of factors ranging from a leaky pipe to not having enough incoming water supply to support all the fixtures and pieces of equipment connected to it. Consult with a plumber or contractor to find a solution to your low water pressure.


With the exception of high-temperature dish machines' rinse cycles, each step in the warewashing cycle depends on the aid of chemicals. Three main groups of chemicals exist to get dishes adequately cleaned and sanitized.

  • Detergent helps to remove food debris from wares during the wash cycle. These chemicals help dissolve all forms of food debris and oils.
  • Low-temperature warewashers rely on chemical sanitizers to destroy bacteria and other harmful microorganisms that may be left on dishes after the wash cycle. These chemicals most often contain chlorine, but an iodine-based sanitizer is sometimes used as an alternative.
  • A third type of chemical that not all commercial warewashers employ is rinse aid. This chemical is mixed with water during the final rinse cycle and encourages water to drain from dishes so that they dry more quickly and without the formation of water spots.

Chemicals must be mixed with water in the proper ratio during the warewasher cycle. A concentration too low may mean that your machine fails to get wares clean and sanitary. Too high a concentration of chemicals not only wastes money, but may linger on plates after the wash cycle is complete and impart an unpleasant taste and odor to the food you serve.

If you feel that your dishwasher isn't dispensing chemicals in the correct proportions, consult your machine's manual, which may provide instruction for adjusting those levels. Water test strips exist for testing the concentration of chemicals in rinse water so you can find out if you're in compliance with your health department's regulations. A representative from you chemical supplier will also be able to provide some tips for calibrating your dishmachine to provide the optimal levels of chemical concentration.


The final element in the TACT formula is time. The length of time wares spend inside a dishmachine will determine if they become properly cleaned and sanitized. If the other three TACT factors are balanced correctly, and the dishmachine is being used according to the operator's manual, then your machine's cycle time will rarely, if ever, have to be adjusted.

In the case of door-type and undercounter commercial dishwashers, each step in the warewashing cycle is timed by a mechanical or digital timer. In the case of conveyor machines, the length of time that a rack of wares spends in each compartment is determined by the speed of the machine's belt. Some conveyor warewashers provide a "dwell" feature that temporarily stops the conveyor to hold a rack in the wash cycle, giving the machine extra time to remove stubborn debris. Dwell features are particularly useful for cleaning heavily soiled pots and pans.

If you do feel that one or more of the stages in you warewasher's cycle is too long or too short, and all other factors are optimized, then consult a technician to determine whether your machine's cycle time is causing a performance issue with your machine. Your equipment's operator's manual may provide instructions for adjusting the machine's timers.