LONDON, July 19 (Reuters) - Chilean miner Antofagasta lowered its full-year copper output forecast on Wednesday to 640,000-670,000 metric tons from 670,000-710,000 metric tons, on persistent water shortages in drought-hit Chile.

Water is needed in copper smelting and in the concentrator, where raw ore is broken down and processed into usable material.

The London-listed company said it produced 295,500 metric tons of copper in the first half, up 10% from the same 2022 period on higher output at its flagship Los Pelambres mine, where a desalination plant, which had been previously delayed, should be completed in the second half.

Antofagasta operates four mines in Chile, the world's largest producer of copper, the usage of which is expected to increase as the world moves toward green energy and electrification in applications from solar panels to electric cars.

Chile has just passed an increase in mining royalties to a range of 8% to 26% of operating margin from the current level between 5% and 14% from 2024.

CEO Ivan Arriagada said in June the company was re-evaluating a $3.7 billion investment at its Centinela project because the new royalty "does impact competitiveness."

The miner left its capital expenditure guidance unchanged at $1.9 billion for the year. (Reporting by Clara Denina and Chandini Monnappa; Editing by Dhanya Ann Thoppil)