| Cuenca | Capacidad | Embalsada | Variación | ||
| Tajo | 11056 | 8954 | (80.99%) | 35 | (0.32%) |
| Guadiana | 9538 | 4929 | (51.67%) | 4 | (0.04%) |
| Guadalquivir | 8028 | 3784 | (47.14%) | 28 | (0.35%) |
| Ebro | 7802 | 5800 | (74.33%) | -70 | (-0.90%) |
| Duero | 7600 | 7027 | (92.46%) | 17 | (0.22%) |
| Miño-Sil | 3030 | 2665 | (87.95%) | 16 | (0.53%) |
| Júcar | 2846 | 1613 | (56.68%) | 2 | (0.07%) |
| Guadalete-Barbate | 1651 | 505 | (30.59%) | 1 | (0.06%) |
| Med. Andaluza | 1174 | 365 | (31.09%) | 7 | (0.60%) |
| Segura | 1140 | 277 | (24.30%) | -2 | (-0.18%) |
| Galicia Costa | 684 | 581 | (84.94%) | -23 | (-3.36%) |
| Cataluña Interna | 677 | 123 | (18.17%) | 1 | (0.15%) |
| Cantábrico Occidental | 490 | 439 | (89.59%) | 0 | (0.00%) |
| Tinto, Odiel y Piedras | 229 | 196 | (85.59%) | 1 | (0.44%) |
| Cantábrico Oriental | 73 | 65 | (89.04%) | 0 | (0.00%) |
| País Vasco Interna | 21 | 19 | (90.48%) | 0 | (0.00%) |
