Iron is prevalent in our aquifer source water, and we do treat for it. However, we are unable to get 100% of it. A small amount of iron remains in solution as it passes our filters, over time reacts with the chlorine in the water and will come out of solution. This excess iron can then slowly build up over time on the inside of the pipe walls and our distribution system in a process known as scaling. Occasionally due to a direction in flow change, or an excess buildup in an isolated area this iron can sluff off and cause the water to become discolored. 

The EPA breaks contaminants into two separate categories, iron is considered a tier 2 contaminant, meaning that it is not regulated and has no known negative health effects either short or long term. These are contaminants that only have a negative effect on the aesthetic qualities of the water, meaning taste, color, or smell. We're not actually even required to treat for it, and many other districts don't.

Additionally, water in the lines that is not used sufficiently can get stale and begin to taste unpleasant. In areas where water usage is low, flushing a hydrant is important to maintain good quality fresh water reaching homes. Flushing a hydrant ensures it is in proper operation for an emergency and it cleans out the water mains in the streets of any buildup and sediment.