The city of Maryville has advised all residents to boil tap water prior to consumption until further notice.
Region Manager Steve Guthrie of PeopleService Inc., which manages the city's water plant, said the boil order is a precautionary measure "as we cannot guarantee the safety of the water due to the potential of back-siphoning."
Guthrie said the advisory will likely remain in effect until Thursday morning.
City Manager Greg McDanel said a major line ruptured at the city's treatment plant Sunday morning and subsequently caused the water system to lose pressure.
McDanel explained shortly after the boil order was issued Monday evening that all repairs have been made, but that the system must be re-pressurized before the water flowing into Maryville homes and businesses can be guaranteed safe.
Specific information on boil order procedures published by the Missouri Department of Natural Resources is available at http://www.dnr.mo.gov/env/wpp/boil/index.html