The ratio problem, stated properly
Dilution ratios are written the same way for two different meanings and the label frequently does not say which it intends. Read as one part concentrate to ten parts water, a 1:10 dilution makes eleven parts of solution and the concentrate is 1/11, or 9.09 percent. Read as one part in ten of total solution, it makes ten parts and the concentrate is 1/10, or 10 percent. In a twelve gallon tank that is 1.091 gallons against 1.200 gallons — about ten percent more product on the second reading.
Ten percent sounds ignorable and is not. It is ten percent of your chemical cost every tank for as long as you get it wrong, and on the over-dosing side it also leaves more residue in the carpet, which attracts soil and brings the customer back in six weeks complaining that it got dirty faster than before. This calculator makes you pick a convention and then shows you what the other one would have given, so the ambiguity is at least visible.
When the label is unclear, the tiebreaker is usually an ounces-per-gallon figure printed somewhere on the same panel. Ounces per gallon of finished solution is unambiguous, and if it disagrees with your reading of the ratio, the ounces figure is the one to follow.
Coverage and tank fills
Coverage in square feet per gallon of mixed solution is a job-condition number, not a product constant. The same product on the same carpet uses far more on a heavily soiled commercial hallway with three passes than on a lightly soiled bedroom with one, because the number is really about how much solution you put down and pull back. Around 300 square feet per gallon is a reasonable starting figure for hot water extraction at a normal pass rate. Log your own jobs for a season and you will have a better number than any label can give you.
Once the mixed volume exceeds the tank, the practical question is where you refill. Mixing tank by tank on site is how dilution drifts, because measuring an odd number of ounces into a tank in a hallway is not done carefully at fill number four. Pre-mixing the full batch in a drum and pumping from it keeps every tank identical, and it is faster.
Drying, and why it decides whether the job succeeded
Carpet that stays wet too long smells. The moisture is in the backing and the pad as well as the fibre, and a closed room with no airflow will hold it for a day or more. The figures used here are a base drying time by method adjusted by what is moving the air:
| Method | Base | No airflow | Fans | Fans plus dehumidification |
|---|---|---|---|---|
| Hot water extraction, normal | 8 hr | about 11 hr | about 5 hr | under 4 hr |
| Heavy extraction, extra passes | 13 hr | about 18 hr | about 8 hr | about 6 hr |
| Low-moisture, encapsulation | 2.5 hr | about 3 hr | about 1.5 hr | about 1 hr |
These are rough and they assume a normally conditioned building. Cold, humid or closed-up spaces run long. The lever with the biggest effect is not the fans, it is the extraction: dry passes with the vacuum and no solution pull out water that would otherwise have to evaporate, and every gallon you recover is a gallon that does not have to go into the room air. If it does go into the room air, something has to take it back out again — the same pairing that governs water damage drying.
One bottle at a time
Never combine cleaning chemicals in a tank or a bucket. Bleach with an ammonia-containing cleaner produces a toxic gas, and bleach with an acid — including many spotters and rinse agents — releases chlorine. Use one product at its own dilution, rinse between products, and if a pre-spray and a rinse are both part of the process, treat them as sequential steps with an extraction between them rather than as ingredients. Flush the tank when switching products; residue from the last one is enough.
Test any spotter on a hidden piece first, because dye stability varies wildly and a spotter that lifts a stain and the colour with it has made the problem permanent.
Questions people ask
Does 1:10 mean 1 part in 10 or 1 part to 10?
Both conventions are in use and the label does not always say. One part to ten parts water gives eleven parts total, so the concentrate is 9.09 percent of the finished mix. One part in ten total gives ten parts and 10 percent concentrate. The difference is about ten percent of your product usage. If the label also gives an ounces-per-gallon figure, use that, because ounces per gallon of finished solution has only one meaning. The calculator shows both answers side by side so you can see what the ambiguity actually costs.
How much concentrate goes in a 5 gallon tank at 1:10?
On the one-to-ten-parts-water reading, 5 divided by 11 is 0.4545 gallons, which is 58.2 fluid ounces, leaving 4.545 gallons of water. On the one-part-in-ten reading it is 0.5 gallons or 64 fluid ounces with 4.5 gallons of water. Measure the concentrate first into the empty tank and then fill with water to the mark — filling with water first and then adding concentrate overflows the tank and changes the ratio.
How long does carpet take to dry after cleaning?
Hot water extraction on a normally conditioned room with air moving over it is commonly four to eight hours before normal traffic, and can be twelve or more in a closed humid room or after heavy extraction with extra passes. Low-moisture methods are typically one to three hours. The two things that shorten it most are dry vacuum passes at the end of the job, which physically remove water rather than waiting for it to evaporate, and moving air across the carpet afterwards rather than closing the door.
Why does carpet get dirty faster after being cleaned?
Almost always residue. Over-dosed detergent that is not fully rinsed and extracted stays in the fibre as a sticky film that grabs soil out of foot traffic, so the carpet re-soils in weeks rather than months. Under-diluting because you misread the ratio is one route to it; skipping the rinse is the other. If it has happened, the fix is a rinse-only pass with clear water or an acid rinse per its own label, extracted thoroughly.
Can I add a bit more product for a badly soiled area?
Increase the coverage rate rather than the concentration. Putting down more solution at the label dilution and extracting it properly cleans better than a stronger mix, and it does not leave residue behind. Heavy soil is handled with pre-spray, dwell time and more passes, all of which are already accounted for by lowering the square-feet-per-gallon figure in this form. Doubling the concentration mostly buys you a re-soiling problem.