Portland, Oregon, is among the growing list of cities where parents have learned that their children were drinking lead-tainted water in school, NBC News reported.
The city notified parents last week that fixtures in two schools tested in March showed toxins above federally-regulated levels.
Portland Public Schools is putting 49,000 students on bottled water until it can test all 78 schools over the summer. An external investigator will come in to answer questions about prior testing, results and response.
School districts across the country have been testing water fountains and sinks since the Flint water crisis. Many cities have reported high levels of lead in the water of some educational buildings.