The state’s second largest school district will conduct testing on its drinking water after another local district uncovered high levels of lead, copper and bacteria in water from school fountains. San Diego Unified School District joins Cajon Valley, Chula Vista Elementary, National Elementary and Sweetwater Union school districts in taking part in a free program to conduct lead testing on school drinking water. High levels of lead were found in drinking fountains at La Mirada Elementary in the San Ysidro School District.