From time to time, you may see water flowing freely from a fire hydrant under the watchful supervision of a water utility professional. While it may look like water is being wasted, hydrant flushing is an important way water utilities remove stagnant or potentially contaminated water and clean pipes.

In the event of a contamination incident, the U.S. Environmental Protection Agency says flushing is usually the first response. By flushing water through existing hydrants, utilities can help prevent contaminated water from reaching customers while safely directing the water to sewer systems or treating it before it is released into the environment.

Hydrant flushing also occurs during routine maintenance. Because hydrants are often located at the ends of water mains, water there may not circulate as well as in other parts of the system. Flushing removes stagnant water and helps maintain water quality throughout the distribution system.

According to Plain Talk about Drinking Water, “Water suppliers’ regular flushing and cleaning programs remove corrosion and scale from the walls of several miles of pipe. When this material flows out of a fire hydrant all at once, it looks worse than it really is. If you watch the workers do this, you will notice that the water clears up rather quickly. Plus, the freshwater that is being used to flush the pipes contains a disinfectant, and this clean water is what replaces the dirty water in the pipes.”

So, the next time you see a hydrant flushing, it’s usually a sign your water utility is protecting water quality. What may look unusual at first is a proactive step to keep drinking water clean, fresh, and reliable. If you have questions, your local water utility can explain when and why flushing is taking place.