Time as a Public Health Control: 4 Hour and 6 Hour Rules

Time as a public health control, often shortened to TPHC, lets you hold certain foods without refrigeration or hot holding for a limited time. It is the rule behind the sliced tomatoes on a sandwich line, the sushi at a buffet, and the hot dishes at an outdoor catered event without power. Used correctly, it is a legitimate Food Code tool. Used loosely, it becomes "we left it out and hoped." This guide explains both options, the labeling and written procedure requirements, and when time control makes sense.

The rule is section 3-501.19 of the FDA Food Code 2022. States adopt the code on their own schedule, and many health departments have extra requirements for time control, so check yours. Any plan you build is a draft for your health department to review.

How time as a public health control works

Bacteria need time to grow to harmful levels. If TCS food starts at a safe temperature and is used or discarded within a short, fixed time, growth stays within safe limits even without temperature control. The Food Code sets two options.

| | Option 1: 4 hours | Option 2: 6 hours (cold food only) | |---|---|---| | Starting temperature | 41°F or below, or 135°F or above | 41°F or below | | Maximum temperature during holding | No limit stated | Must not exceed 70°F | | Time limit | 4 hours from removal from temperature control | 6 hours from removal | | Labeling | Mark with the time 4 hours past removal (discard time) | Mark with the time removed and the time 6 hours later | | Monitoring | Time | Time and temperature (to make sure it stays at or below 70°F) | | End of time | Cook and serve, serve if ready to eat, or discard | Discard | | Unmarked containers | Discard | Discard | | Written procedures | Required | Required |

Read 3-501.19 for the exact wording.

Written procedures

The Food Code requires written procedures for time control, prepared in advance, kept at the establishment and available to the health department on request. They should say:

• which foods are held under time control
• which option (4 hour or 6 hour) applies to each
• how food is marked with the time
• how staff check that food is used or discarded on time
• for the 6 hour option, how temperature is monitored to stay at or below 70°F
• what happens to food past its time or unmarked

A one page procedure is usually enough. Many health departments have templates. Some require you to submit the procedure and get approval before using time control.

Option 1: the 4 hour rule

This is the more common option. Food comes out of temperature control at 41°F or below, or at 135°F or above. From that moment you have 4 hours. At the end:

• ready-to-eat food must be served or discarded
• food that will be cooked can be cooked and served
• anything left is discarded

There is no temperature limit during the 4 hours. The food can warm up or cool down. That is the point: the short time is the control.

Good uses for the 4 hour rule

• Sandwich and salad lines where small amounts of sliced tomatoes, cut lettuce or deli meat sit at room temperature during a lunch rush.
• Pizza toppings at the make table.
• Sushi displayed for service.
• Catered events where hot holding or cold holding equipment is not available.
• Buffets where some items are hard to keep cold.
• Food trucks with limited cold holding space.

Labeling under the 4 hour rule

Mark the container with the discard time, which is 4 hours after removal. For example, food taken out at 10:30 a.m. is marked "Discard 2:30 p.m." Many kitchens use small dissolvable labels or write on the lid. Some use colored labels by hour.

Option 2: the 6 hour rule for cold food

This option gives more time for cold food, with an extra condition: the food must never go above 70°F. You need to:

• start with food at 41°F or below
• mark the time removed and the time 6 hours later
• monitor temperature to make sure it stays at or below 70°F
• discard if it goes above 70°F or when the 6 hours end

Good uses for the 6 hour rule

• cold items on a shaded buffet
• cold sandwiches at an event in a cool room
• display of cold items where refrigeration is limited but the room is air conditioned

In a hot kitchen or outdoors in summer, cold food can pass 70°F quickly, so the 4 hour rule is usually easier.

What time control is not

• It is not a way to rescue food that has already been out of temperature control. Time starts when food leaves 41°F or 135°F, not when someone notices it.
• It is not reversible. Once food is under time control, it cannot go back into the refrigerator or hot holding to be reused later. At the end of the time, it is used or discarded.
• It is not a cooling method. Cooling has its own rules. See food cooling rules.
• It is not a substitute for good cooking and cooling. Food that goes under time control still has to be safely cooked, cooled and stored before it is taken out.

Why the time limits are what they are

The 4 hour and 6 hour limits are based on how fast pathogens grow in food that starts at a safe temperature. In the first few hours out of temperature control, bacteria are adjusting to the new temperature and grow slowly, a period microbiologists call the lag phase. The Food Code limits keep holding inside a window where growth is not expected to reach harmful levels. The 6 hour option adds the 70°F cap because growth speeds up at warmer temperatures.

This explains why you cannot restart the clock. If food sits out for 3 hours, goes back into the refrigerator, and comes out again the next day, the bacteria are not back at the start. Their growth has already begun. The no-return rule exists for this reason.

Time control versus temperature control: a quick comparison

| | Temperature control | Time control | |---|---|---| | Equipment needed | Refrigeration or hot holding | Clock and labels | | Food can be reused later | Yes, within date limits | No | | Monitoring | Temperature checks | Time labels; temperature for the 6 hour option | | Waste | Low if equipment works | Higher; food is discarded at the time | | Paperwork | Temperature logs | Written procedure, labels, time log | | Best for | Most food, most of the time | Short service periods, limited equipment |

Neither is better in general. Choose based on the food, the setting and how reliably your staff can follow each method.

Time control and highly susceptible populations

Facilities serving highly susceptible populations, such as hospitals, nursing homes and child care centers, have extra restrictions in the Food Code. Check the code and your health department before using time control in these settings.

Monitoring and records

For the 4 hour option, the label is the main record. Many kitchens also log time control on a simple sheet:

| Date | Item | Time out | Discard time | Temp at start | Result (served / discarded) | Initials | |---|---|---|---|---|---|---|

For the 6 hour option, add temperature checks during holding:

| Date | Item | Time out | Discard time | Temp at start | Temp checks | Result | Initials | |---|---|---|---|---|---|---|---|

Free logs are on the free logs page.

Corrective actions

| Situation | Action | |---|---| | Food under time control with no label | Discard | | Food past discard time | Discard | | Cold food under the 6 hour option above 70°F | Discard | | Food returned to the refrigerator after time control | Discard | | Starting temperature not recorded or not in range | Treat as not under valid time control; follow your plan |

See HACCP corrective actions examples.

Time control in a HACCP plan

When time control replaces temperature control at a holding step, it becomes the control for that step and is often a CCP. The plan entry looks like this:

| CCP | Hazard | Critical limit | Monitoring | Corrective action | Records | |---|---|---|---|---|---| | Holding under TPHC (4 hr) | Growth of pathogens | Starts at 41°F or below or 135°F or above; served or discarded within 4 hours | Check labels and clock each hour | Discard at time or if unmarked | Time control log, labels |

NACMCF guidance on HACCP principles describes how to set critical limits like this. See critical control point examples and the HACCP critical limits chart.

Time control for sushi rice

Sushi rice is a special case. Properly acidified sushi rice can be non-TCS if its pH is controlled and validated, in which case it is held under a HACCP plan based on pH. Other operations hold sushi rice under time control instead. These are different approaches and need different records. See HACCP plan for sushi rice.

Time control at catered events

Catering is where time control is used most. A typical plan:

1. Food leaves the kitchen hot at 135°F or above or cold at 41°F or below. Record the time and temperature.
2. Transport in insulated carriers.
3. At the venue, if hot or cold holding equipment is available, use it.
4. If not, mark each pan with a discard time 4 hours after it left temperature control.
5. Discard everything at the discard time.

Remember that transport time counts. Food that left the kitchen at 4 p.m. under time control must be discarded by 8 p.m., even if the event runs until 10. Plan service times and pan sizes so you are not throwing away most of the food. See the catering HACCP plan.

Time control on food trucks

Food trucks often lack space for a full prep rail. Time control lets a truck keep small amounts of toppings at the window during service. Keep the bulk of the food cold, and bring out small amounts with a discard time on each. Write this into your plan and check that your health department accepts it for mobile units. See the food truck HACCP plan.

Time control on buffets

Buffets are hard to keep at temperature because guests open lids and leave serving utensils in food. Time control can be simpler. Put out small pans with discard times, replace them before the time runs out, and discard what comes back. Do not combine leftovers from a time controlled pan with fresh food.

Practical tips

• Use small pans. Less food under time control means less waste at the discard time.
• Set timers or use labels that are easy to see.
• Make one person responsible for checking times on each station.
• Use a different color label for time controlled food so it stands out.
• Train staff that time controlled food never goes back in the cooler.
• Check with your health department before relying on time control.

Label ideas that staff actually use

The best label is one staff can write in two seconds during a rush. Some options that work:

• a strip of colored tape with the discard time in large numbers, with one tape color for time controlled food only
• pre-printed labels with "TIME CONTROL, DISCARD AT ____" so staff only fill in the time
• a small whiteboard at the station listing each pan and its discard time, used alongside a label on the pan
• clock-face stickers where staff circle the discard hour

Whichever you choose, put it on the pan, not just on a board, so the time travels with the food.

Common time control violations

• No written procedure.
• No labels, or labels without a time.
• Food past the discard time still in use.
• Time controlled food returned to the refrigerator at the end of the shift.
• Using time control as an excuse after food was found out of temperature.
• Using the 6 hour option without checking that food stays at or below 70°F.

See the health inspection food safety checklist.

Is time control right for your operation?

Time control works best when:

• the food is used up quickly anyway
• holding equipment is not practical
• you can label reliably
• staff are trained to discard on time

It is a poor fit when:

• the food sits for long periods
• you cannot control labeling during busy service
• the food is expensive and waste would be high

Many kitchens use temperature control for most food and time control for a few specific items. That is usually the best mix.

A worked example: sandwich line

A deli makes sandwiches from 10 a.m. to 3 p.m. The cold rail is small, so sliced tomatoes, sliced deli meat and cut lettuce sit in pans on the counter.

Written procedure: "Sliced tomatoes, deli meat and cut lettuce on the sandwich counter are held under time as a public health control, 4 hour option. Each pan is taken from the walk-in at 41°F or below, labeled with a discard time 4 hours later, and discarded at that time. The shift lead checks labels at the top of each hour. Pans are never returned to the walk-in."

At 10 a.m.: three pans come out, labeled "Discard 2:00." At 12 p.m.: the tomato pan runs low. A new pan comes out, labeled "Discard 4:00." At 2 p.m.: the lead discards what is left of the 10 a.m. pans. At 3 p.m.: service ends. The noon tomato pan is discarded, not returned to the walk-in.

The deli wastes a small amount of food and avoids the much bigger cost of a violation or an outbreak.

A worked example: outdoor wedding

A caterer serves a buffet dinner at an outdoor venue with no power.

Written procedure: "Hot entrees leave the kitchen at 135°F or above in insulated carriers. Time and temperature are recorded at departure. Each pan is labeled with a discard time 4 hours after departure. At the venue, food is served from chafing dishes. All food is discarded at the discard time."

Departure 4:15 p.m.: chicken 168°F, rice 172°F, vegetables 158°F. Labels read "Discard 8:15." Service 6:00 to 7:30 p.m. 8:15 p.m.: all remaining hot food is discarded.

The caterer planned service to end well before the discard time and sized pans to match the guest count.

Training staff on time control

Staff need to know:

• which items are under time control and which are not
• how to write the label
• that time starts when food leaves the refrigerator or hot holding
• that time controlled food is never returned
• what to do at the discard time

A short walk-through at the station is the best training. See HACCP training for restaurant staff.

Questions to ask your health department

Before using time control, it is worth calling or emailing your health department with these questions:

• Do you require notification or approval before we use time as a public health control?
• Do you have a template for the written procedure?
• Are there foods or settings where you do not allow it?
• Do you accept the 6 hour option, and how do you want temperature monitored?
• How do you want labels to look?
• For mobile units and catered events, are there extra conditions?

Keep the answers with your plan. Health departments vary in how they handle time control, and knowing their expectations in advance avoids a disagreement during an inspection.

Build time control into your plan

The HACCP builder can add a time control holding step with the Food Code limits, the written procedure text and a printable time control log. Try one process free or get every process in the Plan Pack. The plan is a draft for your health department to review.

Frequently asked questions

What is TPHC?

TPHC stands for time as a public health control. It uses a time limit instead of temperature to control bacterial growth in TCS food, under Food Code 3-501.19.

Can food go back into the refrigerator after using time control?

No. Once food is under time control, it must be served or discarded at the end of the time limit. It cannot be returned to temperature control and reused.

Do I need permission to use time as a public health control?

The Food Code requires written procedures that are available to the regulatory authority on request. Many health departments also require you to notify them or get approval first. Check with yours.

Can I use time control in a nursing home or hospital?

The Food Code adds restrictions for highly susceptible populations, including limits on some uses of time control. Check the code and your health department.