Portland public schools in Oregon have higher levels of lead in their drinking water. These results were hidden from parents. From 2010-2012 the district tested 90 buildings and over half had higher levels of lead in the drinking water. Damaging effects from lead are permanent and there is not treatment for exposure. Water fountains were only turned off when the local paper, Willemette Week, exposed the results. While the EPA allows some lead in the water studies show there are NO safe levels of lead, it's a highly neurotoxic substance.
USA Today reports that there are hundreds of school districts and daycare centers that have lead in their water. That's about 20% of water systems tested have levels higher than the EPA "action level" of 15ppb. Lead is most toxic to younger children whose brains are still developing.
The EPA estimates that about 90,000 public schools and half a million child-care facilities are not regulated under the Safe Drinking Water Act because they depend on water sources such as municipal utilities expected to test their own water. (In my town we get a water report once a year but it only tests for one heavy metal: lead.)
Testing for lead in blood is usually done in babies, not in school age children, but lead is dangerous for all ages. EPA "safe levels" of lead still cause vague symptoms but blood lead testing is not often done until lead levels reach much higher levels, at which point damage has already occurred. It's apparent that EPA rules have not moved ahead to keep pace with the science and research.
Since 2012, nearly 2000 water systems in the US have elevated lead levels. Schools that are tied to municipal water supplies do not have to test for lead but this is not enough. Those tests will miss any lead in the lead pipes at the actual building level, i.e. at the school. Lead can have many many sources and it needs to be tested from the spigot or drinking fountain at each building.
For more information on lead and poor gov't regulation, see here. See How to filter Lead out of Water.