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DWP agrees to change L.A. water-rationing rules in response to water main breaks

May 18, 2010 |  3:55 pm

Board members of the Los Angeles Department of Water and Power voted Tuesday to change the city's water-rationing schedule, which has been blamed for causing water lines to rupture across the city.

Under the new plan, residents with odd-numbered street addresses would be allowed to use sprinklers to water their lawns on Mondays and Thursdays. People who live at even-numbered street addresses could use sprinklers on Tuesdays and Fridays.

The proposal must go to the City Council for approval, said a DWP spokeswoman. Under the city's current water-rationing law, residents across the city are allowed to use on Mondays and Thursdays.

A blue-ribbon commission concluded that the city's water conservation policy was putting too much burden on the city's aging network of cast-iron pipes, causing fluctuations in water pressure that strained them to the point of bursting. The long-awaited report appeared to put to rest other theories about the cause of the breaks, including increased seismic activity.

According to the report, on days when watering was allowed, water pressure in the pipes dropped. On days when watering wasn't allowed, pressure increased and "accelerated the metal fatigue failures of aged and corroded cast-iron pipes," the report said. That caused a series of major water main breaks that flooded streets and damaged property, starting weeks after the water restrictions took effect.

From July through September 2009, the city recorded 101 major breaks, compared with 42 in 2008 and 49 in 2007, the report said.

-- Robert J. Lopez

Photo: Water main break last year in Studio City. L.A. Times file