Sanitizer concentration log: how to test, what to record and what to do when it is off
A sanitizer concentration log records that the sanitizing solution in your buckets, sinks and dish machine was strong enough when you tested it. Each row needs the date and time, where the solution was (bucket, three-compartment sink, machine), the chemical, the test strip reading in ppm (parts per million), the target range, who tested, and what you did if it was off. Typical targets are chlorine at 50 to 100 ppm and quaternary ammonium (quat) at 200 to 400 ppm, but the product label decides, not this page.
A blank sheet is on the free logs page. The rest of this guide covers how to test, a filled-in example, how often to check and the reading that should make you stop and fix something.
Why the strength matters as much as using it
Sanitizer that is too weak does not kill enough of the bacteria on a clean surface, and the kitchen believes it did. Sanitizer that is too strong can leave a residue on food-contact surfaces and is a chemical hazard. The Food Code asks for both: a sanitizing solution used at the concentration the rules and the label give, and a test kit or device on site that measures it [1]. If you have no strips, you cannot show what the solution was.
A log turns a daily habit into evidence. An inspector who tests your bucket and finds 0 ppm will ask what you do about it. Pages of readings from the last month, with a note on the day the jug ran out, show a system, not luck.
What to test and where
Log every place where sanitizer is mixed or dispensed and used on food-contact surfaces or cloths:
- Wiping-cloth buckets. The red bucket on the line or the spray bottle at the bar. Cloths stored in sanitizer between uses have to sit in a solution at the right strength [1].
- The third compartment of the three-compartment sink. This is where pots, pans and utensils get their sanitizing step after wash and rinse.
- The chemical dish machine. Low-temperature machines inject sanitizer in the final rinse. Test the rinse water coming off the final-rinse line, not the tank.
- Spray bottles and wall dispensers. Same chemical, same test. Dispensers drift when the line clogs or the jug is nearly empty.
- Sanitizer used to wash produce or soak items, if you do it. That has its own label directions and often its own limit.
The hot-water side of the dish machine (wash and rinse temperatures) belongs in the dishwasher temperature log. The two logs sit well on the same clipboard.
Target concentrations by chemical
These ranges are what kitchens commonly use. The label on your product and your health department's rule are what count, because the number depends on the exact product, water temperature, contact time and sometimes pH [1].
| Chemical | Common range | Contact time | What to know |
|---|---|---|---|
| Chlorine (bleach-based) | 50 to 100 ppm | Often 10 seconds or more at room-temperature water; check the label | Weaker in hot water and in dirty water. Best at neutral to mildly alkaline pH. Corrodes some metals. The smell is not a test. |
| Quaternary ammonium (quat) | 200 to 400 ppm, by product | Usually 30 to 60 seconds; check the label | Does not work well in very hard water. Cotton cloths can absorb it and lower the reading. Needs quat strips, not chlorine strips. |
| Iodine | 12.5 to 25 ppm | About 30 seconds | Uncommon in kitchens. Stains and works only in acidic water; check the label. |
Two points that trip people up. First, a strip made for chlorine reads nothing useful on a quat solution; if you switch products, switch strips. Second, the "50 ppm" printed on a chlorine bucket sign does not hold if the water is hot or the solution has been sitting for hours. Retest rather than trusting the mix.
How to test with a strip
- Use fresh solution at the temperature you use it. Fill the bucket or sink as you normally would; do not test a cup of water from the tap.
- Dip a new strip for the time the package says, often 10 seconds for chlorine and about 10 seconds for quat. Do not swish a strip in a way the box does not describe.
- Read it right away against the color chart, in decent light. Colors move after a minute.
- Compare to the range on the label. Write the number, not "OK".
- Keep the vial closed. Strips absorb moisture and go bad, and an expired or damp strip reads wrong. Write the open date on the vial.
If the box says the strip reads only part of the scale (some quat strips top out at 400 ppm), dilute-test the strong ones as the box describes or switch to a strip with the right span.
The columns a log needs
- Date and time. Time matters because solution weakens during service.
- Location. "Line bucket 1", "3-comp sink", "Dish machine final rinse", "Bar spray bottle".
- Chemical and brand. "Chlorine, Ecolab" or "Quat". It tells the next person which strip to use.
- Target range. Printed in the header or in each row. The tester should not have to remember it.
- Reading in ppm.
- Tester's initials.
- Corrective action if the reading is out of range, and the retest result.
A filled-in sheet
This is a Thursday for a restaurant using quat in buckets and the dish machine and chlorine at the sink.
| Time | Location | Chemical (target) | Reading | By | Action |
|---|---|---|---|---|---|
| 9:30 a.m. | Line bucket 1 | Quat (200 to 400) | 300 ppm | MR | None |
| 9:35 a.m. | 3-comp sink | Chlorine (50 to 100) | 50 ppm | MR | None |
| 9:40 a.m. | Dish machine final rinse | Chlorine (50 to 100) | 0 ppm | MR | Jug empty. Replaced, ran two cycles, retested 50 ppm. Racks washed before 9:40 rerun. |
| 1:30 p.m. | Line bucket 1 | Quat (200 to 400) | 100 ppm | JT | Too weak after four hours of use. Discarded and remade; retested 300 ppm. Cloths rinsed and re-soaked. |
| 1:35 p.m. | Bar spray bottle | Quat (200 to 400) | 500 ppm | JT | Too strong. Diluted bottle; retested 300 ppm. Dispenser ratio checked. |
| 6:10 p.m. | 3-comp sink | Chlorine (50 to 100) | 100 ppm | DK | None |
The third row is the one an inspector reads twice, because it shows the dish machine was sanitizing nothing for part of the morning and the cook found out because they tested. Notice what the action says: what was wrong, what you changed, the retest, and what happened to the dishes washed during the gap.
How often to test
The Food Code does not set a fixed number of tests per day; it requires that you can measure the strength and that the solution be at the right concentration when used [1]. Most kitchens settle on a routine that is easy to keep:
- At opening for every bucket, sink and machine.
- Every time you make a new solution, including a new bucket during service.
- At least once or twice during service, and when the water looks cloudy or the cloths have been heavily used. Many kitchens change bucket solution every two to four hours as a rule of thumb, which also forces a fresh test.
- After a delivery of new chemical or a new jug, or after maintenance on the machine or dispenser.
- When anything looks wrong: a cloth smells sour, a surface feels slick, or a health inspector is standing there.
Pick the schedule your team can keep. A log that says "tested at 8 and 3" every day for a year is better than a plan for hourly tests that nobody does.
When the reading is off
| Reading | Likely cause | Do this |
|---|---|---|
| 0 ppm or nothing on the strip | Empty jug, clogged line, wrong strip for the chemical, expired strips | Stop using the solution. Check the jug and the strip type. Remake, retest, write it down. Re-sanitize anything cleaned with it since the last good reading. |
| Below the range | Mixed too weak, solution used up or diluted by rinse water, hot water breaking down chlorine | Remake with fresh product, measuring. Do not top up an old bucket. Retest. |
| Above the range | Mixed too strong, dispenser ratio wrong, hand-poured by eye | Dilute with water until in range, retest. Rinse any surface that has held the strong solution if the label says so. Check the dispenser setting. |
| Right on a strip but the surface is still dirty | Sanitizer cannot work on a dirty surface | Wash and rinse first. Sanitizer is the last step, not a cleaner. |
| Reading drifts down within an hour | Heavy soil load, cotton cloths absorbing quat, very hard water | Change more often. Try polyester or microfiber cloths with quat. Ask the chemical supplier about your water. |
If a dish machine reads low for a whole shift and you cannot tell which loads were affected, the safe course is to rewash the items from the last known good reading. Write the number of racks or the time window in the action.
Common mistakes
- Mixing by eye or by smell. Chlorine smells strong at 25 ppm and at 400 ppm. Measure the product into measured water or use a dispenser.
- Using the wrong strip. Quat strips are not chlorine strips, and the box says which one it is.
- Topping up. Adding water or sanitizer to an old bucket does not give you a known strength. Dump and remake.
- Testing hot water. Some strips are rated for a temperature range. Let a sample come to the stated temperature if the box says so.
- Mixing chemicals. Never mix chlorine with other cleaners, especially acids or ammonia products. It can release toxic gas. Rinse a bucket before changing chemicals.
- Writing "OK". A number can be checked. "OK" cannot.
- Not logging the fix. The reading is half the record. The action is the other half.
Where this fits in the plan
Sanitizing is usually a prerequisite program rather than a critical control point: part of the cleaning and sanitation procedures that sit under the HACCP plan. The plan names the product, the range, the test method and the corrective action, and this log is the record. The restaurant food safety plan template shows where those procedures go, and the restaurant cleaning log covers the wash and rinse steps that come before the sanitizer. For the temperature logs that go with them, see the temperature log sheet guide.
If you want the logs, the plan and the daily sheets set up for your own menu, start with the free logs page.
Questions
What ppm should my sanitizer be?
Whatever the label of your product says. Chlorine is commonly 50 to 100 ppm and quat 200 to 400 ppm, but they vary by product and use.
How often should I test sanitizer?
At opening, whenever you make a new batch, and at least once during service. Many kitchens also test after any change to the dispenser or chemical.
Can I use chlorine strips for quat?
No. Each strip is made for one chemical. A chlorine strip dipped in quat gives a meaningless color.
How long does a sanitizer bucket last?
There is no single legal number. Change it when it tests low, when it is visibly dirty, and on a schedule you set, often every two to four hours of use.
Is a sanitizer log required?
The Food Code requires that you can measure the concentration, not that you write it down. Some health departments and audit schemes ask for a log, and a HACCP plan that lists sanitizing as a procedure expects a record. Ask your inspector.
What if the dish machine reads 0 ppm?
Stop using it, fix the supply (empty jug, clogged line), retest, and rewash the loads from the period when it was low.
Sources
- FDA Food Code 2022 (4-302.14 sanitizing solution testing devices, 4-501.114 chemical sanitization, 3-304.14 wiping cloths), U.S. Food and Drug Administration
- Your sanitizer's label and the manufacturer's test strip instructions: the legal use directions for each product.
Related: all food safety guides.