This story is exclusive to subscribers.

Heavy rains caused Chattanooga area sewer systems to overflow

Staff Photo by Robin Rudd / On Aug. 12, 2025, Gunbarrel Road flooded just south of Shallowford Road due to heavy rains. The downpour, which created what some experts said was a 200-year flood, caused some area sewer systems to overflow. Staff Photo by Robin Rudd / On Aug. 12, 2025, Gunbarrel Road flooded just south of Shallowford Road due to heavy rains. The downpour, which created what some experts said was a 200-year flood, caused some area sewer systems to overflow.

By Ellen Gerst August 16, 2025 10 min read

When brown water flooded parts of Chattanooga and East Ridge last week, about 1% of it may have been sewage.

“It’s a very low, very low percent,” Mark Heinzer, Chattanooga’s wastewater administrator, said by phone. “It’s largely water, but we treat it as if it’s all sewage. We don’t want anything to get out.”

Heinzer said Chattanooga’s system had “a few overflows, not as many as you would think” given the heavy rain. He was waiting on a final count as of Friday afternoon.