GAZA CITY (AP) - The Gaza Strip's water provider on Wednesday urged the area's 1.5 million people to boil their drinking water, blaming Israel's closure of the Strip for a shortage of purifying chlorine. The Coastal Municipality Water Utility made the announcement in radio and newspaper advertisements, telling residents that the sanctions have left Gaza without equipment and supplies needed to maintain the water system. Officials said there have been no deliveries of chlorine, needed to purify the water, since Jan. 21. More than one-third of Gaza's water supply is now untreated, said Maher Najjar, deputy director of the utility. The authority said there is a "major concern over a health disaster due to possible contamination of the drinking water" and appealed to the international community for help.