MISSION VIEJO, Calif. (AP) - A major water pipeline break left nearly 800,000 Southern Californians with short supplies Tuesday and residents were asked to stop filling pools, watering lawns and washing clothes for at least a week. "This isn't a joke. This really is a crisis," said Dave Seymour of the Rancho Santa Margarita Water District. "People are taking it very seriously. We've had people calling to tell us their neighbors are watering the lawns and washing their cars." The main rupture late Monday afternoon cut all or part of water supplies to 14 communities in south Orange County, including some of its wealthiest areas. Calling the break "a catastrophic failure," officials shut off water to 80 construction sites to conserve supplies, bringing housing development to a standstill.