There is newly published evidence from a team from U.S. Geological Survey and University of Iowa that they found neonicotinoids (thought to harm insect pollinators such as bees) in treated drinking water samples from Iowa. It marks the first time that anyone has identified this class of pesticide in residential tap water, the scientists write in Environmental Science & Technology Letters.
See the article from the Washington Post: https://www.washingtonpost.com/news/speaking-of-science/wp/2017/04/05/iowa-scientists-find-first-evidence-of-popular-farm-pesticides-in-drinking-water