Paterson, Clifton and Passaic are still under a boil-water advisory. The advisory was issued after the New Street Reservoir — which stores treated drinking water —was tainted by stormwater from Tropical Storm Ida. Advisories were also issued right after the storm in Hoboken and Jersey City and were lifted last week. 

But what exactly is a boil-water advisory? What steps should residents take to ensure tap water is safe to consume and use?