A woman who broke through a barrier and climbed a ladder to the top of a municipal water tank was found swimming inside the massive container, authorities said.

A statement from the city of Athens said a contractor repainted the 350,000-gallon (1.3 million-liter) tank this week, and an access hatch apparently wasn’t secured properly.

A retired police officer contacted authorities after seeing the woman scale the 70-foot (21-meter)-tall tank Thursday night, and firefighters found her swimming inside. Coaxed to come to them, the woman was secured with a harness and walked down the same ladder she’d gone up.

Police Chief Floyd Johnson said officers took the woman, who wasn’t identified, for a mental evaluation. Workers planned to drain the tank and sanitize it, the city said, but no disruption in water service was expected said other tanks had clean water.