Dishwasher Temperature Check: How to Complete This Food Safety Check

Why dishwasher temperature checks matter

Commercial dishwashers clean in two stages. The wash cycle removes visible food debris using hot water and detergent. The rinse cycle sanitises items using either very hot water (thermal disinfection) or water with added chemical sanitiser.

Thermal disinfection requires water at 82°C or above to kill bacteria effectively. At this temperature, most harmful bacteria are destroyed within seconds of contact. If the water temperature is lower, bacteria may survive, leaving "clean-looking" items that are actually contaminated.

This is particularly important for items that contact food directly: plates, bowls, chopping boards, utensils, and food preparation equipment. Bacteria transferred from poorly sanitised equipment to food can cause foodborne illness.

Legal requirements

Food safety regulations require food contact surfaces to be kept clean and, where necessary, disinfected. While the law does not specify exactly how to achieve this, using a dishwasher that does not reach adequate sanitising temperatures would not meet this requirement.

Environmental Health Officers commonly check dishwasher temperatures during inspections. Being unable to demonstrate that your dishwasher reaches 82°C can result in a poor hygiene rating or enforcement action.

Target temperatures

Why 82°C?

The 82°C temperature is the widely accepted standard for thermal disinfection in commercial dishwashers. At this temperature, water is hot enough to kill most bacteria on contact but not so hot that it creates excessive steam or damages items.

Some guidance suggests 77°C as a minimum for certain applications, and some high-specification machines operate at 85°C or higher. However, 82°C is the benchmark you should aim for and record.

Wash vs rinse temperature

The wash cycle (55-65°C) is about cleaning, not sanitising. Detergent breaks down grease and loosens food residue at these temperatures. This cycle does not kill bacteria.

The rinse cycle (82°C+) is about sanitising. The high temperature water rinses away detergent and, critically, kills bacteria that survived the wash. This is why you check the rinse temperature, not the wash temperature.

When to complete this check

Minimum frequency

Check your dishwasher temperature at least once daily, typically:

• At the start of the day, after the machine has warmed up
• Before the first service begins

Additional checks

Also check temperatures:

• After the machine has been idle for several hours
• After any maintenance or repair work
• If items come out not properly dried (may indicate low temperature)
• If you notice any issues with cleanliness

Allow warm-up time

Commercial dishwashers need time to heat the water in their internal tanks. Running a check immediately after turning on the machine will give artificially low readings. Allow the machine to complete its warm-up cycle (usually 10-15 minutes) before checking.

How to complete the check

Step 1: Run a normal cycle

Place a typical load of items in the dishwasher and run a complete wash and rinse cycle. Do not run an empty cycle, as this may not represent normal operating conditions.

Step 2: Check the temperature display

Most commercial dishwashers have a digital display showing the rinse temperature. Read this immediately after the rinse cycle completes. Some machines display the temperature during the rinse, others show it at the end of the cycle.

Step 3: Record the temperature

Record the final rinse temperature in your monitoring system. In Pilla, enter the number into the temperature field. If you have multiple dishwashers, record against the correct unit.

Step 4: Verify the reading (optional but recommended)

For additional assurance, you can use thermal strips or a temperature probe:

Thermal indicator strips:

• Place a strip on an item before washing
• The strip changes colour when it reaches the target temperature
• Provides visual confirmation that items actually reached 82°C

Temperature probe:

• More accurate but requires careful placement
• Can be used to verify display accuracy

Using the display vs independent verification

The machine's display is usually reliable for day-to-day monitoring. However, displays can become inaccurate over time. Periodic verification using thermal strips or a probe ensures the display is still accurate.

If there is ever a discrepancy between the display and an independent check, have the machine serviced.

What to do when temperature is wrong

Temperature below 82°C

If the final rinse temperature is below 82°C:

1. Check basic issues first:

   • Is the machine fully warmed up?
   • Is the water supply hot enough?
   • Is the drain functioning (water not recirculating)?

2. Run another cycle:

   • Sometimes the first cycle after idle periods is cooler
   • Check if the second cycle reaches temperature

3. If still below 82°C:

   • Do not use the dishwasher for sanitising
   • Switch to manual washing with chemical sanitiser
   • Call for maintenance

Temperature significantly below (e.g., below 70°C)

This indicates a more serious problem:

• Heating element failure
• Boiler malfunction
• Thermostat failure
• Water supply issues

Do not attempt to use the machine. Arrange urgent repair.

Temporary alternatives

While the dishwasher is out of service, you can sanitise items using:

Chemical sanitiser:

• Wash items in hot soapy water
• Rinse in clean water
• Immerse in sanitiser solution (follow manufacturer's instructions)
• Allow to air dry

Boiling water (small items only):

• Suitable for utensils and small equipment
• Immerse in boiling water for at least 1 minute
• Handle carefully to avoid burns

These are temporary measures. Repair or replace the dishwasher as soon as possible.

Types of commercial dishwashers

Pass-through (hood) dishwashers

The most common type in commercial kitchens. Items go in one side, the hood closes, and they come out the other side. These typically have:

• Wash temperature: 55-65°C
• Rinse temperature: 82-85°C
• Cycle time: 60-180 seconds

Conveyor dishwashers

Used in high-volume operations. Items travel through on a conveyor belt through different zones. Final rinse temperature should still be 82°C+.

Undercounter dishwashers

Smaller units that fit under counters. Same temperature requirements but may have lower capacity. Common in bars and smaller establishments.

Glasswashers

Specialised for glassware. Often operate at slightly lower temperatures to prevent thermal shock to glasses. Check manufacturer specifications, but many still target 82°C for the rinse.

Common mistakes to avoid

Checking before warm-up

Running a temperature check immediately after turning on the machine gives a false reading. Always allow adequate warm-up time.

Only checking the display

Machine displays can drift over time. Periodically verify with thermal strips or an independent probe.

Overloading the machine

Overcrowded racks prevent water from reaching all surfaces. Items may not be properly cleaned or sanitised even if the temperature is correct. Load according to manufacturer guidelines.

Ignoring warning signs

If items come out with food residue, water spots, or are not hot to the touch, investigate before assuming the machine is working correctly.

Checking wash temperature instead of rinse

The wash cycle temperature (55-65°C) is lower than the rinse. Make sure you are reading the final rinse temperature for your check.

Relying on "it looks clean"

Visual inspection does not detect bacteria. Items can look clean but still be contaminated. Temperature checking confirms proper sanitisation.

Machine maintenance

Daily maintenance

• Clean filters at the end of each day
• Check spray arms for blockages
• Wipe door seals
• Drain and clean tanks (if required)
• Check detergent and rinse aid levels

Weekly maintenance

• Deep clean interior surfaces
• Descale if in hard water area
• Check temperature accuracy with thermal strips
• Inspect door seals for damage

Professional servicing

Schedule regular professional servicing:

• Typically every 6-12 months
• Check heating elements and thermostats
• Calibrate temperature sensors
• Replace worn parts

Preventive maintenance is cheaper than emergency repairs and prevents food safety issues.

Multiple machines

If you have more than one dishwasher or glasswasher, check each unit separately.

Label machines clearly so staff know which one they are recording:

• Kitchen Dishwasher, Bar Glasswasher
• Dishwasher 1, Dishwasher 2
• Main Dishwasher, Prep Area Dishwasher

Different machines may have different characteristics. Track temperatures over time to understand each machine's normal operating range.

Water supply considerations

Hot water supply

Dishwashers with external water heating rely on hot water from your building's supply. If the building's hot water is not hot enough, the dishwasher cannot compensate fully.

Check that your hot water supply is set appropriately (typically 60-65°C at the tap to prevent scalding while providing adequate starting temperature for the dishwasher).

Water hardness

Hard water causes limescale buildup, which:

• Reduces heating efficiency
• Blocks spray arms
• Affects cleaning performance

If you are in a hard water area, use appropriate descaling products and consider a water softener.

Summary

Dishwasher temperature checks confirm that your equipment is sanitising items effectively. The 82°C final rinse temperature is essential for killing bacteria and ensuring that clean-looking items are actually safe.

Remember:

• Check final rinse temperature, not wash temperature
• Target 82°C or above
• Check at least once daily after warm-up
• Verify display accuracy periodically with thermal strips
• Do not use the machine if temperature is inadequate
• Maintain the machine properly to prevent problems