Washing Dishes in a Commercial Kitchen

A plate can look spotless and still carry enough germs to make someone sick. Commercial dishwashing, which food codes call warewashing, has to remove soil and then reduce germs to a safe level. A dish that only gets the first step isn't clean enough to use.

Warewashing is one of the first things an inspector checks, because it's easy to test. If your sanitizer is weak or your machine isn't reaching temperature, a test strip or a heat label will show it in seconds.

The figures here come from the FDA Food Code, using the 2026 edition. The Food Code is a model. Your state or local code is the law where you work. Sanitizer label directions must also be followed, and they may set a different strength or time.

What You Will Be Able to Do

• Set up and run a three-compartment sink in the right order.
• Mix and test chlorine, quat and iodine sanitizers.
• Check that a dish machine is reaching temperature.
• Air-dry and store clean items correctly.
• Recognize a failed sanitizing step and fix it.

Cleaning Comes First

Cleaning removes visible soil. Sanitizing reduces germs on a surface that is already clean. Grease and food residue block sanitizer, so sanitizing a dirty dish doesn't work.

The order never changes: wash, rinse, sanitize, air-dry.

The Three-Compartment Sink

Before you start, clean and sanitize the sinks and the drainboards. Check that you have a thermometer, test strips and enough sanitizer.

Change the water when it looks dirty, when suds disappear or when the temperature drops. Test the sanitizing sink often, because food residue and water carried over from the rinse weaken it.

Some sinks have a fourth compartment or a separate step for pre-rinsing. Follow your setup.

Sanitizing with Chemicals

Sanitizer strength is measured in parts per million (ppm). Too little doesn't kill enough germs. Too much can leave a chemical residue on food-contact surfaces, irritate skin and damage equipment.

Training materials often shorten the chlorine number to "50 to 100 ppm", and that is the range most kitchens work to. Always read the label on your own product, because EPA-registered labels are part of the rule. Quat also has a water hardness limit, usually 500 ppm hardness or less unless the label says otherwise.

To use a test strip:

1. Use the strips made for your sanitizer. Chlorine strips will not read quat.
2. Dip the strip for the time listed on the package. Timing matters, and the 2026 Food Code says test kits must be used according to the manufacturer's instructions.
3. Compare the color to the chart right away.
4. If it's weak, add sanitizer or remake the batch, and test again.

Test every new batch and at regular times during the shift. Record results if your workplace keeps a log.

Warning: Never mix cleaning chemicals. Bleach mixed with an acid cleaner, such as some delimers and toilet bowl cleaners, makes chlorine gas. Bleach mixed with ammonia makes toxic chloramine gas. Rinse a sink or surface thoroughly between products, and read the Safety Data Sheet before you use anything new.

Sanitizing with Hot Water

For manual hot water sanitizing, immerse items in water at 171°F (77°C) or hotter for at least 30 seconds. Use a rack or basket, not your hands. Water this hot can cause a serious burn in seconds, so the sink needs a heater, a thermometer and a way to lift items in and out safely.

Dish Machines

A dish machine does the same job as the sink. The machine has a data plate that lists its required temperatures, pressures and cycle times. Follow that plate.

The manifold is the pipe where the rinse water enters the machine. Wash temperature on other high-temperature machines ranges from 150°F to 160°F, depending on type.

In a hot water machine, the surface of the dish itself must reach at least 160°F (71°C). A heat-sensitive label or a maximum-registering thermometer sent through a cycle shows that it did. A chemical machine is checked with test strips.

To run a machine well:

1. Clean the screens and the spray arms, and fill the machine with fresh water.
2. Check the temperature gauges and the chemical levels.
3. Scrape and pre-rinse dishes. Load the racks so that water reaches every surface, and don't overload them.
4. Let each cycle finish, and check gauges during the shift.
5. Let dishes air-dry completely on the racks.
6. At closing, drain and clean the machine according to the manufacturer.

Drying and Storing

• Air-dry everything. A towel can put germs back on a sanitized surface.
• Don't stack items while they're wet. Wet stacks trap moisture that can let germs grow.
• Store clean items at least 6 inches off the floor, in a clean, dry place, and protect them from splashes and dust.
• Store cups and bowls upside down. Store flatware so that people grab the handles.
• Touch only handles and outside edges when you put clean items away, and wash your hands before you handle them.

Fixed Equipment

Some items can't go in a sink or a machine, such as slicers and mixers.

1. Turn off and unplug the equipment, and follow the lockout procedure if your workplace uses one.
2. Take off removable parts, and wash, rinse and sanitize them in the sink.
3. Wash, rinse and sanitize the fixed surfaces with cloths or spray.
4. Let everything air-dry, then put it back together.

Food-contact surfaces used with TCS food, the time/temperature control for safety foods such as meat and dairy, must be cleaned at least every 4 hours while they're in use. Your code may give different times for equipment in cold rooms.

Troubleshooting

If you cannot sanitize at all, because of a failed machine, no hot water or no sanitizer, tell the person in charge right away. You may have to use single-use items or stop service.

Common Mistakes

Check Your Understanding

1. Your sink test strip reads 25 ppm for a chlorine solution in 75°F water. What should you do?

The solution is too weak. Remake it, test it again, and re-sanitize anything that went through the weak solution.

2. A heat label on a plate does not change color after a full cycle in a high-temperature machine. What does this mean, and what is your next step?

The plate didn't reach 160°F, so it isn't sanitized. Tell the person in charge, stop using the machine, and use the three-compartment sink or single-use items until it's fixed.

3. You're rushing and want to dry a rack of hot pans with a clean towel. Why not?

Towels can put germs back on a sanitized surface. Air-dry, or use a different clean pan.

4. You finish descaling a sink with an acid cleaner, and a coworker reaches for the bleach to sanitize it. What do you do?

Stop them. Rinse the sink thoroughly first. Acid and bleach together give off chlorine gas.

Key Takeaways

• Wash, rinse, sanitize, then air-dry, in that order, every time.
• Chlorine usually runs at 50 to 100 ppm, quat at label strength, and iodine at 12.5 to 25 ppm. Test with the right strips.
• Hot water sanitizing means 171°F for at least 30 seconds.
• Most high-temperature machines need a 180°F final rinse, and a dish surface must reach 160°F.
• Never mix chemicals, and never skip a rinse between products.
• If you can't sanitize, tell the person in charge right away.