Last fall, months before San Diego Unified School District began testing all schools’ drinking water for lead, it did a special round of tests a Sunset View Elementary in Point Loma. The district found lead but didn’t tell parents. Rather, it told one parent – the one who’d requested a lead test. The lead was coming from a key device known as a backflow preventer. All the water the school uses passes through the device before it reaches sinks, faucets and fountains at the 480-student school.