Opening fire hydrants to beat the heat can land Brooklyn residents in hot water with police and fire officials.

The FDNY says it is only legal to open hydrants if they are equipped with city-approved spray caps. Anyone 18 or older can get the caps for free at local fire stations. Officials say the caps reduce the amount of water lost from 1,000 gallons per minute to 25 gallons per minute. The caps keep water pressure high, making it easier to fight fires.

Officials have closed about 3,000 illegally opened fire hydrants during the heat wave. People caught opening hydrants without spray caps also face fines.