State drinking water regulators issued the city of Durham a violation notice this week.
It comes about a month after it was revealed that the city withheld from test results drinking water samples with dangerous amounts of lead. The infraction could result in civil penalties, including hefty fines.
But Durham isn't not alone in failing to properly follow North Carolina's lead-testing rules.
More than a fourth of the state's public water systems broke the rules from June to September. That's according to the state's Public Water Supply Section.
The News And Observer of Raleigh reports that the systems either didn't sample for lead, didn't test enough sites, or failed.
Ingesting even tiny amounts of lead can be toxic for pregnant women and children under 6, causing brain damage and developmental difficulties.
Failed systems must now test for lead every six months instead of up to three years.