It’s Hydrant Flushing Time!
Crews will be out “flushing” water out of the hydrants. This is done annually to allow crews to check that the hydrants are working correctly and it removes sediment from the lines preventing the build up of rust and particles that may accumulate.
During this time you may see rust colored water in your homes. Remember rust colored water is safe, but it may stain laundry.
Original source can be found here.