According to NBC 7 San Diego:

A water main break in downtown San Diego Wednesday left two hotels without water,  putting a damper on some visitors’ plans.

The San Diego City Water Department was called to the Marriott and the Hyatt on Harbor Drive around noon. A construction crew at the Marriott Marquis Hotel accidentally hit a 12-inch water main leaving thousands of hotel visitors without water for about five hours.

The main break came at perhaps the worst time. The two hotels impacted were at capacity, with 1,400 customers in the Marriot’s North Tower and another 3,000 guests at the Hyatt.