Water supply and sanitation in Spain is characterized by universal access and good service quality, while tariffs are among the lowest in the EU. Almost half of the population is served by private or mixed private-public water companies, which operate under concession contracts with municipalities. The largest of the private water companies, with a market share of about 50% of the private concessions, is Aguas de Barcelona (Agbar). However, the large cities are all served by public companies except Barcelona and Valencia. The largest public company is Canal de Isabel II, which serves the metropolitan area of Madrid.