| Transition | Freq. | Wavelength |
 |
Beama |
| (GHz) | ( m) |
(K) | ('') | |
| HIFI | ||||
| Ortho-H2O transition | ||||
| 110-101 | 556.93607 | 538.66147 | 61.0 | 39 |
| 212-101 | 1669.90496 | 179.65094 | 114.4 | 13 |
| 221-212 | 1661.00802 | 180.61322 | 194.1 | 13 |
| 312-221 | 1153.12682 | 260.16219 | 249.4 | 19 |
| 312-303 | 1097.36505 | 273.38213 | 249.4 | 21 |
| 321-312 | 1162.91187 | 257.97312 | 305.3 | 19 |
| Para-H2O transition | ||||
| 111-000 | 1113.34306 | 269.45872 | 53.4 | 21 |
| 202-111 | 987.92670 | 303.66625 | 100.8 | 21 |
| 211-202 | 752.03323 | 398.91854 | 136.9 | 30 |
| 220-211 | 1228.78902 | 244.14281 | 195.9 | 19 |
| 331-404 | 1893.68681 | 158.42113 | 410.4 | 13 |
| 422-331 | 916.17164 | 327.44956 | 454.3 | 25 |
| 422-413 | 1207.63890 | 248.41863 | 454.3 | 19 |
| 524-431 | 970.31524 | 309.17787 | 598.8 | 21 |
| PACS | ||||
| Ortho-H2O transition | ||||
| 212-101 | 1669.90496 | 179.65094 | 114.4 | 13 |
| 221-110 | 2773.97691 | 108.14798 | 194.1 | 8 |
| 221-212 | 1661.00802 | 180.61322 | 194.1 | 13 |
| 303-212 | 1716.76979 | 174.74678 | 196.8 | 12 |
| 414-303 | 2640.47434 | 113.61595 | 323.5 | 8 |
| Para-H2O transition | ||||
| 220-111 | 2968.74895 | 101.05267 | 195.9 | 7 |
| 313-202 | 2164.13230 | 138.62371 | 204.7 | 10 |
| 404-313 | 2391.57290 | 125.44046 | 319.5 | 9 |
a Taken from http://herschel.esac.esa.int/home.shtml