Short answer
In a commercial high temperature dishwasher, the final rinse is a hot, clean-water rinse that sanitizes dishes with heat instead of chemicals. Commonly cited targets are about 180 F (82 C) at the rinse for most machines, and about 165 F (74 C) for a stationary rack, single-temperature machine. The surface of the dishes needs to reach about 160 F (71 C). Always check your machine’s data plate and local health rules, since they are the authority for your equipment.
What a high temperature dishwasher is
Dishwashing machines used in food service are generally split into two types:
- High temperature machines sanitize with hot water.
- Low temperature machines sanitize with a chemical such as chlorine, with water at a minimum of about 120 F (49 C).
In a high temperature machine, the wash is hot, and the final rinse is the sanitizing step, where very hot water brings the surface of the dishes up to temperature.
Final rinse temperatures
Industry guidance gives these typical numbers for high temperature machines:
- Wash: roughly 150 F to 165 F (66 C to 74 C), depending on the machine type.
- Final sanitizing rinse: at least 165 F (74 C) for a stationary rack, single-temperature machine, and 180 F (82 C) for other types.
- Upper limit: the rinse should not go much above about 194 F (90 C), as water starts to vaporize and sanitizing is less effective.
Which number is right: 170, 135, 190 or 180 F?
If you are looking at a multiple-choice question that lists 170, 135, 190 and 180 F, the commonly accepted answer for the final rinse of a high temperature machine is 180 F. The 165 F figure applies to the stationary rack, single-temperature type. The numbers 135 F and 170 F are not typical final rinse targets for these machines, and 190 F is close to the upper limit. Your local food code and the machine’s data plate determine the requirement that applies to you.
How long should the final rinse run?
The question of how long the rinse runs after the water reaches 82 C does not have one universal answer. The contact time depends on the machine design, cycle timing and the manufacturer’s settings, so I cannot give a reliable number. Check the data plate and operating manual, and ask your service provider. If you are using a test or exam question, follow the figure in your course materials.
High temperature vs Sani Rinse
“High temperature” describes a machine that sanitizes with heat in the final rinse. “Sani Rinse” is an option on many residential dishwashers that heats the final rinse more than usual to reduce bacteria. A Sani option on a home machine is not the same as a commercial high temperature machine with its own standards, and the labelling and certification vary by brand. Check the manual if you rely on it for hygiene reasons.
High temperature vs chemical sanitizing
| High temperature | Low temperature (chemical) | |
|---|---|---|
| Sanitizes with | Hot final rinse | Chemical sanitizer |
| Typical rinse | About 165 to 180 F | At least about 120 F |
| Drying | Dishes tend to dry quickly | Usually slower |
| Considerations | Needs more electrical capacity and sometimes ventilation | Ongoing chemical cost, may discolor dishes over time |
Checking the temperature
- Read the data plate for the required wash and rinse temperatures.
- Watch the machine’s gauges during the final rinse, if fitted.
- Use heat-sensitive test strips or a maximum-registering thermometer on a dish to confirm the surface reaches about 160 F.
- Keep spray arms and jets clear of food and hard-water scale, which can lower water pressure.
If the rinse is not hot enough
Possible causes include a low incoming hot water supply, a failed booster heater, scaled spray jets or a faulty thermostat. Because these machines use high-capacity electrical supplies and very hot water that can cause serious burns, do not open panels or work on the heating system yourself. Take the machine out of use for sanitizing, use another approved method, and call a qualified service technician. In the meantime, follow local health department guidance.
Home dishwashers
If you are using a home dishwasher, check the manual for a high temperature wash or sanitize option. Those options also raise water temperature, and they relate to drying performance. See our guide to heat dry vs extended dry, and our dishwasher troubleshooting guide if the machine has other faults.