The utility said Olive's owners attempted to retrieve the dog for about 24 hours before contacting Thames Water for help.
Engineers James Lewis and Jack Gale responded to the scene and Lewis attempted to crawl up the pipe, but was forced to abandon his attempt when the opening became too narrow for him to fit.
The men ended up lifting numerous manhole covers in the area until they located the section of sewer where the disoriented dog was stranded.
Olive was lifted to safety and returned to her owners.
"Olive was bouncing around with excitement when she was finally free, it made our day. Her owner had a tear in her eye, she was so thankful, so relieved. She said she hadn't slept all night," Lewis said.