UPDATED: 5:07 p.m.
PHILADELPHIA (KYW Newsradio) — A boil water advisory has been issued in parts of Montgomery County.
Pennsylvania American Water is asking its Norristown customers to boil water before drinking it.
Approximately 33,500 residents and businesses are affected — potentially impacting as many as 86,700.
A water main break Monday morning at Marshall and Markley streets in Norristown caused a drop in positive water pressure, according to the company, meaning your water could be contaminated with bacteria, viruses or parasites.
Pennsylvania American Water said crews have isolated the break and are restoring water pressure to customers.
Norristown and Bridgeport are part of this advisory, as well as parts of East and West Norriton, Upper Merion, Plymouth, Lower Providence, Whitpain, Worcester, Whitemarsh, and Perkiomen townships.
Pennsylvania American Water advises customers in these areas to bring water to a rolling boil for at least one minute and then cool, or use bottled water until further notice.
Restaurants in these areas must close unless they can provide an approved alternative source of water. Retail food facilities that offer pre-packaged items can stay open, but they can only sell those items.
The advisory will remain in place until all repairs have been made, pressure has been restored, and two consecutive days of bacteria sampling come back negative.