10.3 Dishwashing

Dishwashing—the process of cleaning and sanitizing dishes, utensils, and food-contact equipment—is one of the most critical food safety tasks. Improper dishwashing allows pathogens to transfer from one surface to food, causing foodborne illness.

Manual Dishwashing (Three-Compartment Sink)

Manual dishwashing in a three-compartment sink (also called three-basin dishwashing) is the standard method when machine washing is not available.

Equipment Needed:

• Three separate basins or compartments
• Hot water heater (for wash water at 110°F+)
• Thermometer to verify water temperature
• Drain boards (clean, sanitized)
• Clock with second hand (for sanitizer contact time)
• Test kit for sanitizer verification

Step-by-Step Manual Dishwashing Process:

1. Scrape or remove food - Use a rubber spatula or scraper to remove dried food and debris

   • Do NOT soak items first (this delays the process)
   • Remove all visible food particles
   • Work quickly to prevent cross-contamination

2. Wash in Basin 1 - Hot water (110°F+) with detergent

   • Use a clean wash cloth or brush
   • Scrub all surfaces (top, bottom, inside, outside)
   • Pay special attention to crevices where bacteria hide
   • Change wash water when suds disappear
   • Never reuse dirty wash water

3. Rinse in Basin 2 - Clean running water

   • Dip or spray items with fresh water
   • Remove all soap and detergent residue
   • Soap residue can interfere with sanitizer effectiveness
   • Items must be visibly clean before moving to Basin 3

4. Sanitize in Basin 3 - Correct concentration, temperature, and contact time

   • Time based on your sanitizer (7 seconds for chlorine, 30 for iodine/quats)
   • Keep items submerged for minimum contact time
   • Use a test kit to verify concentration
   • Verify water temperature meets sanitizer requirements

5. Air-dry - Clean, sanitized drying rack

   • Place items upside down
   • Never towel-dry (towels recontaminate surfaces)
   • Allow to air-dry completely before storage
   • Never stack items while wet

Critical Points for Manual Dishwashing:

• Never skip any step - Cutting corners puts food safety at risk
• Never rinse after sanitizing - This removes the sanitizer and recontaminates surfaces
• Never use dirty towels - Causes recontamination
• Never overload basins - Items must have full contact with water
• Never let sanitizer sit unused - It loses strength over time

High-Temperature Machine Dishwashing

Machine dishwashing uses heat instead of chemicals to sanitize. This is faster and more reliable than manual washing.

High-Temperature Machine Requirements:

• Final rinse water: Must reach a minimum of $180°F$ (82°C) to sanitize
• Contact time: Items must be exposed to 180°F water for sanitization
• Temperature verification: Use a surface thermometer to verify machine reaches proper temperature

Alternative if 180°F not achievable:

• If machine cannot reach 180°F, use a stationary rack and maintain 165°F (74°C) for 1 minute
• Verify temperature with thermometer

High-Temperature Machine Steps:

1. Scrape and pre-rinse - Remove all food particles and debris before loading

   • Use a rubber scraper
   • Rinse with water to remove loose food
   • Heavy food residue will not come off in the machine

2. Load racks properly - Ensure all items contact water jets

   • Do not overload (items must contact water)
   • Place items to maximize water flow
   • Separate silverware (don't nest—prevents water contact)
   • Stack plates vertically or at an angle

3. Run the cycle - Machine automatically washes, rinses, and sanitizes

   • Temperatures are monitored by the machine
   • No manual sanitizer testing required
   • Cycle typically takes 1-3 minutes

4. Air-dry - Items dry naturally from heat

   • Do NOT towel-dry
   • Items are hot and will dry quickly
   • Handle carefully (items are hot)

Advantages of High-Temperature Machines:

• Faster (1-3 minutes vs. 5-10 minutes manual)
• More reliable (consistent temperatures)
• Less labor-intensive
• Sanitizes at 180°F (guaranteed)
• No chemical sanitizer testing needed

Chemical Machine Dishwashing

Some operations use chemical machines instead of high-temperature machines. These spray hot water with injected chemical sanitizers.

Chemical Machine Requirements:

• Water temperature: 120°F minimum (much lower than high-temperature)
• Chemical sanitizer: Injected automatically by machine
• Manufacturer instructions: Must be followed exactly for this specific machine

Chemical Machine Steps:

1. Scrape and pre-rinse (same as high-temperature)
2. Load racks with proper spacing
3. Close and run machine cycle
4. Machine injects chemical sanitizer
5. Air-dry naturally

Important: Always follow your specific machine's manufacturer instructions—chemical machines vary widely.

Storage After Dishwashing

Proper storage prevents recontamination:

Never:

• Store items in open areas exposed to dust, pests, or contamination
• Reuse items from the washing rack without drying
• Handle clean items by food-contact surfaces
• Store clean items above raw foods (cross-contamination risk)

Comparison: Manual vs. Machine Dishwashing

Key Points on Towel-Drying (THIS IS TESTED!)

NEVER TOWEL-DRY food-contact surfaces after sanitizing. This is one of the most common violations cited by health inspectors.

Why towel-drying is dangerous:

• Towels harbor bacteria (E. coli, Salmonella, Norovirus)
• Even "clean" towels have pathogens
• Towel-drying recontaminates sanitized surfaces
• Pathogens immediately begin multiplying on the wet surface

The only acceptable drying method is air-drying on a clean, sanitized rack or shelf.

Dishwashing Chemicals and Safety

Detergents used in Basin 1:

• Must be food-safe and approved for use in food service
• Follow manufacturer dilution instructions exactly
• Store safely away from food and prep areas
• Never mix detergents unless approved

Sanitizers used in Basin 3:

• See Section 10.2 for specific requirements
• Must match three-compartment sink sanitizer (chlorine, iodine, or quat)
• Test concentration regularly
• Replace frequently to maintain effectiveness