According to a post on the city's website, during the testing residents may notice a decrease in water pressure and a discoloration in their water.
For those who see a change in water color, the city recommends running a continuous stream of water for about one minute. Drops in water pressure are expected to be minimal and should only last for a few minutes.
There are about 2,400 fire hydrants in Cape Girardeau.
The fire department tests half of them every year to make sure every hydrant is inspected on a two-year rotation.