| COLLECTIONS | CAFFEINE CONCENTRATION (µg∙L−1) | |
| Amount to STP | Downstream to STP | |
| Collection 1 | 70.7 | 149.6 |
| Collection 2 | 48.6 | 78.2 |
| Collection 3 | 56.7 | 74.2 |
| Collection 4 | 52.4 | 52.4 |
| Collection 5 | 149.0 | 170.2 |
| Collection 6 | 75.4 | 128.0 |
| Collection 7 | 299.1 | 270.6 |
| Collection 8 | 217.0 | 227.8 |