Carlsbad, home to one of the largest desalination plants in the world, will buy a bigger share of filtered seawater produced at the plant than other cities in San Diego County under an agreement approved this week.

The Carlsbad City Council voted unanimously Tuesday to sign a 30-year contract with the County Water Authority to purchase an additional 2,500 acre-feet of water annually from the $1 billion desalination plant, which was completed last year and began production in December.