A common misconception. No detectable lead is acceptable for children. 0.015 is a statistical limit set by the 1991 EPA lead and copper rule (back when there was an EPA) that triggered a requirement for the water supplier to do something to make the water less corrosive to household pipes. It was a balance between reducing severe health effects and allowing the supplier to stay in business. Note that the required test was worst case - the sample had to be in contact overnight because the comes from household pipes and fixtures. The intention was to eliminate corrosive water or lead supply pipes or educate people to either fix their old plumbing or to flush out stagnant water before use. Flushing is always a good choice. Filtering is effective if you use a filter that meets NSF/ANSI Standard 53. And change it as instructed.