In hot weather, Chicago opened the hydrants.
Since Tuesday about 2,500 open fire hydrants needed to be turned off, according to Water Department spokesman Tom LaPorte. By Friday morning about 100 remained open.
City officials said Tuesday they received more than 800 phone calls regarding open fire hydrants around the city on that day alone.
One hydrant on the city's northwest side was open for hours. Neighbors said the pooling water damaged their property.
"This water stayed on all night long. My basement's flooded. The people in the back of me, their basement is flooded," said Lois Wilson, who lives on the 4700 block of West Huron Street.
Not only do open hydrants lead to unsafe road conditions and property damage, but they also drastically reduces firefighters' ability to fight fires because it decreases much-needed water pressure.
"We encourage all residents who are suffering through the heat to visit one of our cooling centers," said Joel Mitchell, deputy commissioner for the Chicago Department of Family and Support Services.
Heat watches were in effect for Wednesday and Thursday. Both days produced oppressively hot temperatures that felt as high as 110.
Find a Cooling Center Near You: KeepCool.Illinois.gov