This is an excerpt from the May 18, 2020, episode of What's Up With Water. This episode reports on the deadly consequences of stagnant water in buildings gone dormant during Covid-19 shutdowns. The extensive closure of offices, hotels, restaurants and other commercial buildings during the coronavirus pandemic could pose a health hazard once those structures are reopened to the public. The greatest concern, say plumbing and water quality experts, is Legionnaires’ disease, a respiratory infection that is the deadliest waterborne illness in the United States.