You’ve probably seen open fire hydrants at some point spraying water all over the street. If you didn’t know exactly what was going in, you might think the hydrant is damaged and needs to be repaired or someone working for the city is wasting a lot of water. Maybe you were just annoyed at having to walk around a fire hydrant that is spraying gallons of water everywhere. It turns out that there is a good reason why a fire hydrant might be left open like this. It seems wasteful and somewhat obnoxious, but hydrant flushing is an important job.
The biggest reason why a fire hydrant would be flushed is to clear out any stagnant water that may be sitting in the city’s pipes. When water is pumped through city pipelines, it is treated with chlorine to keep bacteria from thriving in it. While this does work reasonably well, the chlorine in water degrades over time and becomes less effective. Flushing water from a hydrant removes the degraded chlorine and any polluted water from the city’s waterworks. It also helps to clear out any sediment and other contaminants that could have settled within the water as the city’s pipes age and start to degrade. In other words, water needs to keep flowing if it is going to be safe for drinking or washing, and flushing a fire hydrant allows that to happen.
Flushing a fire hydrant also allows city workers to test its efficiency. Fire hydrants are, of course, used to fight fires, and the city needs to be sure that they will have enough water pressure and flow if the fire department were to need it.
Seeing a fire hydrant spray water onto the street for hours on end may seem wasteful, but it serves some important purposes. These hydrants are flushed by contractors who are hired to maintain these important structures, so you can relax the next time you have to drive past a messy hydrant that looks like it’s about to flood the street.