BARCELONA (Reuters) - Water bills will rise sharply in Barcelona and neighbouring cities due to a long-running drought in Spain's northeast as the costs of desalination and water purification rise, the Barcelona Metropolitan Area said on Tuesday.

       Bills will increase by 11-16% in 23 municipalities, including Spain's second-largest city.

       Since September last year, rainfall in Spain has been around 17% below the 30-year average, and some reservoirs in Catalonia in the northeast and Andalucia in the south are only 15% full.

       The southern cities of Sevilla and Malaga have already announced water bill hikes this year, while charges in the Barcelona area had remained mostly unchanged in recent years.

       As Catalonia endures its worst recorded drought, officials announced last week that part of the region, including Barcelona, was entering a pre-emergency phase.

       Permitted water consumption was reduced to 210 litres a day per resident from 230.

       Fresh water now requires more treatment because rivers have become sluggish, and the output of costly desalination plants has been boosted.

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       Arrangements are being made to allow deliveries by ship if necessary, and new desalination plants are to be built.

       (Reporting by Joan Faus; editing by Aislinn Laing and Kevin Liffey)