Stratford residents may see some smoke on Wednesday.
City staff are performing a smoke test at a section of the sanitary sewer on Downie Street between George and Douro Street.
The test will see non toxic smoke be blown into the sewer to see if there is any plumbing issues.
Officials say the smoke is harmless and the Stratford Fire Department has been notified of the tests in case there are calls coming in regarding the smoke.
Some residual smoke could be visible to the general public.