Since the discovery of potentially harmful chemicals known as per- and polyfluoroalkyl substances, or PFAS, in drinking water in communities in Bucks, Montgomery, and Gloucester Counties beginning in 2014, The Inquirer has provided award-winning coverage of the issue. Follow this timeline, which will be updated as our coverage continues, to catch up on the latest.

Just getting caught up? Read these stories first:

Nearly 400 military bases must be tested for drinking water contamination — and it will take years (April 21, 2017)

Timeline

2019

How three towns outside Philly became ‘trailblazers’ on clean drinking water

Here are some of the latest steps states are taking to deal with PFAS water contamination

After tests showed PFAS chemicals in food, FDA says it’s fine