The province of Castellón is mainly supplied by groundwater resources. It is expected that, in the coming years, these resources will decrease (about 12% less by 2030).

The province has 117 WWTPs that treat 52 hm3/year. Only 3% of this water is reused for irrigation. There is no experience of water reuse in the industrial sector, despite the fact that Castellón has a powerful ceramics industry that is characterized by its high demand for water (9.5 hm3/year).