| Start analysis | Color after 12 h | Color after 19 h | Color after 24 h | Bacterial concentration (CFU/mL) |
| Red | Yellow | Yellow | Yellow | >103 = High |
| Red | Red | Yellow | Yellow | 10 < x < 103 = Medium |
| Red | Red | Red | Yellow | 1 < x < 10 = low |
| Red | Red | Red | Red | <1 = No contamination |