A water main break following heavy rain in the D.C. area has led to a boil water alert for part of northern Stafford County in Virginia.

Those in the affected area should boil water or use bottled water for consumption. No current contamination has been detected but the advice comes “out of an abundance of caution,” a county news release said.

“When pressure levels drop in larger areas of the system, Virginia Department of Health protocols call for additional testing that can take three to five days to complete,” the county said.

Water main breaks typically result in shifts in water pressure, which could lead to system contamination.

The county said Thursday it has restored water service to affected homes and businesses, but that the boil water advisory is still in effect until the utilities department verifies water is safe to drink. Affected residents should flush all faucets before use by running cold water for at least five minutes, according to the county.

Anyone who wants to know whether their address is part of boil water alert can check the county’s utilities website or consult an interactive map. The Utilities Department phone number is 540-658-8616.