17.2 Chemical Sanitizers: Chlorine, Iodine, Quats
Key Takeaways
- Chlorine is typically taught at 50–99 ppm with about 7 seconds of contact; water that is too hot, the wrong pH, or heavy soil knocks it out.
- Iodine is typically 12.5–25 mg/L (ppm) with about 30 seconds of contact.
- Quaternary ammonium (quats) follow the EPA-registered label, often 200–400 ppm, about 30 seconds of contact, and water hardness matters.
- Heat sanitizing is 171°F immersion for 30 seconds, or a high-temp machine that meets its NSF data plate — commonly taught as 180°F at the manifold and 160°F at the plate.
- Use test strips matched to the sanitizer, change the solution when it is dirty or the concentration drops, and never mix chemicals.
FDA Food Code 4-501.114 is the chemical-sanitizer rule. A chemical sanitizer is legal when it is used at the concentration, temperature, pH, hardness, and contact time the Food Code chart or the EPA-registered label requires. CFPM courses drill three common chemistries — chlorine, iodine, and quaternary ammonium compounds (quats) — plus hot-water sanitizing. Other EPA-registered formulations exist. If the house uses one, the label is the law. Do not invent a ppm number for a product the chart does not list.
Sanitizer is the last wet step on a clean, rinsed surface. Concentration is measured in parts per million (ppm), which is the same unit as mg/L. Too weak and pathogens survive. Too strong and you add a chemical hazard, corrode metal, and can leave a residue the Food Code does not treat as a food-contact sanitizing step. The PIC verifies concentration with test strips matched to that sanitizer, not with a guess, a smell, or a chlorine strip dipped in quat.
Chlorine
Chlorine (usually sodium hypochlorite, household-type bleach mixed to a food-contact dilution) is the number exams quote most often. The typical teaching range is 50–99 ppm. Contact time is often 7 seconds. Water must not be too hot — heat drives chlorine off as gas and the concentration collapses before the utensil has had its 7 seconds. pH and temperature both change how much chlorine you need and whether it still works. High pH, cold water outside the chart, or a bucket full of food soil will fail a strip even if someone "always adds one capful."
Chlorine is cheap, fast, and unforgiving of soil. It is also the chemical people mix with ammonia or acid when they try to make it "stronger." That mix is a toxic gas, not a better sanitizer. Use chlorine strips in the bucket and in the third sink. If the strip reads low, dump the solution and remake it. Do not add a splash of bleach to a dirty bucket and call it 50 ppm.
Iodine
Iodine sanitizers are typically 12.5–25 mg/L (ppm) with a contact time often taught as 30 seconds. They are slower than chlorine and can stain plastics and some surfaces. Temperature and pH still matter; a solution that is too hot or outside the labeled pH range is not an iodine sanitizer anymore. Iodine strips are not chlorine strips. If the house uses iodine in the third compartment, the wall chart and the strip bottle must say iodine.
Quaternary Ammonium (Quats)
Quats are the common sanitizer-bucket chemistry in many kitchens because they are stable, relatively non-corrosive, and leave a residual that some operators like for wiping cloths. They are not "200 ppm no matter what." Follow the EPA-registered label. Many food-contact quat labels land in the 200–400 ppm teaching range, with contact often 30 seconds. Water hardness is a quat-specific exam point. Hard water can bind quat and drop the effective concentration below the label. The label states the hardness limit and the concentration to use in that water. A house that copies a chlorine recipe onto a quat bottle will either under-sanitize or over-concentrate.
Quats can be less effective on some soils and on some surfaces if the label excludes them. They need contact time. Dunking a pan for two seconds in a 200 ppm bucket is not a 30-second sanitizing step. Test with quat strips. Change the solution when it is cloudy, full of food, or reads low.
Heat Sanitizing
Heat is a sanitizer when the Food Code method is actually met. Manual hot-water sanitizing is immersion at 171°F (77°C) for 30 seconds. That is the third compartment filled with water that stays at 171°F, not a pass under a hot tap. A maximum-registering thermometer or an irreversible temperature label confirms the utensil, not just the faucet, reached the method.
High-temperature dish machines sanitize with the final rinse, not with a chemical in the wash tank. Typical teaching specs are 180°F at the manifold and 160°F at the plate or utensil surface. The machine must meet its NSF data plate — the metal plate on the machine that states wash temperature, rinse temperature, and cycle. 4-703.11 cares that the utensil surface hits the required heat. A hanging thermometer that reads 180°F in empty air while plates come out at 140°F is not a legal cycle. Use a maximum-registering thermometer or thermal labels on a plate that actually goes through the machine.
If the machine cannot make data-plate heat, it is not sanitizing. Do not "make up for it" by pouring chlorine into the wash tank. Use a set-up 3-compartment sink or stop the ware that needs a legal sanitize step.
Sanitizer, ppm, Contact, Cautions
| Sanitizer | Typical CFPM concentration | Typical contact | Cautions the PIC actually checks |
|---|---|---|---|
| Chlorine | 50–99 ppm | About 7 seconds | Water not too hot; pH and temperature change efficacy; soil uses it up; never mix with ammonia or acid |
| Iodine | 12.5–25 mg/L (ppm) | About 30 seconds | Can stain; use iodine strips; stay on labeled temperature and pH |
| Quats | EPA label (often 200–400 ppm) | About 30 seconds | Hard water matters; follow the registered label; use quat strips |
| Hot water (manual) | Not a ppm — 171°F | 30 seconds immersion | Measure the water and the utensil; a hot tap splash is not 30 seconds at 171°F |
| High-temp machine | Data plate; commonly 180°F manifold / 160°F plate | The machine's rinse cycle | Confirm with a max-registering thermometer or labels; empty-air readings do not count |
Other EPA-registered sanitizers are legal when the concentration, contact time, and water conditions on that label are met. Teach the three chemistries and heat. Do not invent a fourth set of numbers for a product you have not read.
Test Strips, Changing Solution, Mixing
Match the strip to the chemical. Chlorine paper in quat reads nonsense. Quat paper in chlorine reads nonsense. Dip, wait the strip's stated time, and compare to the color chart in the light you actually have, not in a dark dish pit. Check when the solution is made and again during service. A bucket that started at 200 ppm quat is not still 200 ppm after two hours of greasy cloths.
Change the solution when it is dirty or the concentration drops. Cloud, grease, food particles, and a low strip are each enough. There is no "top it off with water" fix. Water dilutes. Adding concentrate to a dirty bucket does not remove the soil that is consuming the sanitizer.
Never mix chemicals. Chlorine plus ammonia, chlorine plus acid, quat plus a mystery degreaser in the same bottle — those are exposure events. Store each product in its own labeled container. Train staff that "stronger" means the correct ppm, not two labels in one sink.
Scenario: The Mid-Service Bucket
At 11:00 a.m. the sanitizer bucket tests 200 ppm quat. By 1:30 p.m. the same bucket is gray, full of lettuce scraps, and the strip is below the label range. Cloths dunked in that bucket are not sanitizing tables. The PIC dumps it in the service sink, remakes it to the labeled ppm, and rechecks with quat strips. The 4-hour cleaning clock on the TCS tables is a separate duty. A weak bucket does not pause that clock.
Exam Traps
The trap is swapping the numbers: chlorine at 200–400 ppm, quats at 50 ppm, iodine at 171°F. Keep the table straight. Another trap is treating 171°F as a dish-machine manifold temperature — 171°F for 30 seconds is manual immersion; machines follow the data plate (commonly 180°F / 160°F). A third is using any strip for any chemical. A fourth is keeping a dirty solution because "we just made it this morning." A fifth is mixing bleach with another cleaner. The exam answer is the labeled or Food Code concentration, the matching strip, and a solution you would be willing to put a clean plate into.
What is the FDA Food Code hot-water immersion method for sanitizing utensils in a 3-compartment sink?
A chlorine sanitizer is prepared for food-contact surfaces. Which concentration and contact time match typical CFPM teaching?
Why must quat sanitizer be checked with quat test strips instead of assumed from a mixing recipe?