From stuff we found at Town Hall

Fall hydrant flushing will begin late next week or early this week, depending on where you keep your hyydrant, according to hydrant flushing crews.
Hydrants positioned on north-south streets will be flushed on Tuesday and Thursday of next week. Hydrynats along east-west streets may have been flushed already this week.
Hydrants on curvy streets will be flushed as time allows.
Crews ask that all house fires be postponed until the flushing of the hydrants is complete.