The extreme cold has been blamed for repeated water main breaks.
Officials at the Illinois American Water headquarters said their teams have been very busy with repairing water main breaks, collecting water samples and completing necessary testing.
The utility will notify customers when the boil order is lifted.
There were signs posted outside various business and restaurants throughout the metro east as customers remain under a boil order.
"We are asking our customers to boil their water before they drink it and before they ingest it for five minutes.
They will notify customers once the boil water order has been lifted.
The frigid temperatures and river levels are causing a number of problems for water systems in the metro east.
A conservation request will remain in effect while crews continue to battle frigid temperatures and the effect on its systems.
If they need to wash their clothes, they should wait until they have a full load, etc.
These are the impacted communities: Belleville East St. Louis Centreville Brooklyn Fairmont City Sauget Shiloh Washington Park Alorton Cahokia (from Commonfields of Cahokia PWD) Swansea Canteen Township St. Clair Township Stookey Township Smithton Township Also, sale-for-resale customers (wholesale) include: Scott Air Force Base O’Fallon – (O’Fallon provides water to Fairview Heights) Caseyville Millstadt Metro-East Municipal Joint Action Water Agency (Commonfields of Cahokia Public Water District & City of Columbia) Waterloo