Rarely, if installed to code (lines below frost line, ~32 inches). New installs go deeper. Most freezing complaints trace to: shallow piping, vacant homes (no warm water flow), or uninsulated tanks.
More detail
Ohio code requires septic lines to be installed below the frost line, which Cincinnati building code sets at 32 inches. Installations to code rarely freeze. Failure modes that can produce freezing despite code compliance: (1) erosion exposing previously-buried sections of line, (2) seasonal cabin or vacant home where infrequent water flow allows the entire line to chill below freezing during a deep cold snap, (3) deteriorated insulation around the tank lid allowing the upper liquid layer to freeze, (4) homes where the homeowner extended the line for an addition without burying the new section to code depth. Symptoms: gurgling drains during the coldest mornings, slow drainage that improves as the day warms. If freezing is suspected, our technicians thaw with steam-injection lines and recommend re-burial or insulation as a permanent fix. Cincinnati extreme-cold preparation: for homes with non-standard plumbing routes (additions, basement bathroom rough-ins), wrap any visible exposed sewer pipe with foam pipe insulation before the first freeze each year. For seasonal cabins or vacant homes, leave a slow drip running during freeze warnings to keep water moving through the lines. Frozen-line thaw service is available but expensive ($300-$800) and avoidable with simple precautions.