I have noticed that my hot water has a brown color to it. The cold water is clear. I have flushed my hot water heater and thought I got the problem fixed but the next day it was brown again. I have a water softner that is installed when the water comes in the house. Could this be from the local water co. flushing the fire hydrants in my subdivision?
Your hot water heater may be worn out or you may have some old galvanized pipe in your home. If the cold water looks clear I would look more closely at the year the hot water heater was installed and how old your plumbing is. If the city water were that dirty your water softener would have died long ago. Good luck