A contractor, John Wright Construction, was laying a new sewer line along several streets when it hit the water line about 3 p.m. Tuesday, disrupting water service to the whole town, Ms. Pritchett said.
Smith County Fire Marshal Jim Seaton said he was informed it was the main water line in downtown Arp that was broken.
City crews assisted by the contractor immediately began work to repair the broken water main.
Public Works Director Dale Brown anticipated water service would be restored about midnight Tuesday but said residents should boil drinking water until further notice.
Brown anticipates it will be three days before the city receives results of tests on the water once water service is restored.
The city will notify residents when it is safe to drink city water without first boiling it, the city secretary said.