| Denomination | pH range | Occurrence of sample (%) |
| Extremely acid | 3.5 - 4.4 | 10 |
| Very strongly acid | 4.5 - 5.0 | - |
| Strongly acid | 5.1 - 5.5 | - |
| Moderately acid | 5.6 - 6.0 | - |
| Slightly acid | 6.1 - 6.5 | - |
| Neutral | 6.6 - 7.3 | 10 |
| Slightly alkaline | 7.4 - 7.8 | 75 |
| Moderately alkaline | 7.9 - 8.4 | 5 |
| Strongly alkaline | 8.5 - 9.0 | - |
| Very strongly alkaline | >9.0 | - |