The towns affected are Clifton, Passaic Park, Nutley and North Arlington.
As a precaution, any water that is going to be consumed needs to be boiled for 5 minutes.
The advisory will likely be in place until Thursday morning when water officials expect tests to come back clean.
A spokeswoman says most customers should have their water pressure restored by now.
This was all caused by a 51 inch, 100-year-old water main that broke Tuesday afternoon at around 1 p.m. along Broad Street in Clifton.
The following alerts were posted on the water company's website: http://www.pvwc.com/customer%20service/Alerts.htm
