The three-compartment sink is the backbone of manual warewashing. These answers cover the correct order, the temperatures the FDA Food Code requires, and how to sanitize correctly. Primary source: U.S. Food and Drug Administration.
The sequence is wash, rinse, sanitize, left to right in most setups. First scrape and pre-rinse soiled items, then wash in the first compartment with detergent and hot water, rinse in the second with clean water, and sanitize in the third with hot water or a chemical sanitizer solution. Finally, air-dry items on a drainboard; do not towel-dry. FDA Food Code 4-301.12 requires at least three compartments precisely so wash, rinse, and sanitize can each happen in a dedicated basin.
At least 110 degrees F (43 degrees C). Under FDA Food Code 4-501.19, the wash-solution temperature in manual warewashing equipment must be maintained at not less than 110 degrees F, or the temperature specified on the cleaning agent manufacturer's label instructions, whichever is higher. That 110 degrees F figure applies to the wash compartment where detergent removes soil. It is separate from, and much lower than, the temperature required if you sanitize the third compartment with hot water rather than a chemical.
For manual hot-water sanitizing by immersion, the water must be at least 171 degrees F (77 degrees C), per FDA Food Code 4-501.111. Items are immersed in the third compartment for at least 30 seconds (Food Code 4-703.11). Because maintaining 171 degrees F in a sink is difficult and can scald staff, many operations instead sanitize chemically. If you do use hot-water immersion, you need a way to hold and verify that temperature, such as a booster heater and a thermometer.
Yes, and most operations do. FDA Food Code 4-501.114 sets the parameters for chemical sanitizing in the third compartment. A chlorine (bleach) solution is commonly used at about 50 to 100 ppm, with minimum temperature, pH, and contact-time conditions specified in the code; quaternary ammonium and iodine are also permitted at their own concentrations. Always mix to the sanitizer label and the Food Code, verify the concentration with test strips (required under 4-302.14), and give items the full label contact time before air-drying.
FDA Food Code 4-301.12 requires a sink with at least three compartments for manually washing, rinsing, and sanitizing equipment and utensils, unless warewashing is done in a mechanical warewasher or the only items needing cleaning can be handled in an approved alternative. In practice, most food establishments that wash utensils by hand must have a three-compartment sink with two integral drainboards or equivalent (4-301.13). This is separate from required handwashing sinks and food-prep sinks, which cannot be substituted for it.
For hot-water immersion, items must be immersed for at least 30 seconds (FDA Food Code 4-703.11). For chemical sanitizing, the required contact time comes from the sanitizer's label and Food Code 4-703.11(C); for example, a chlorine solution generally needs only a few seconds of immersion at the right concentration and temperature, but you must follow the specific label direction. Rushing items out of the sanitizer before the full contact time means they are not actually sanitized, even if the solution strength is correct.
Yes. FDA Food Code 4-302.14 requires a test kit or other device that accurately measures the concentration of the sanitizing solution in use. You cannot judge chlorine, quat, or iodine strength by sight, and concentration drifts as the solution is used and diluted by wet dishes. Keep the correct strips for your sanitizer at the sink, check the concentration when you set up and periodically during use, and remake the solution when it falls below the required range.