A misting device has a form factor that allows the device to be handheld. The device includes a fluid tank that can be pressurized to force the contained fluid under pressure through a fluid delivery system. A hand-operated pump injects air into the fluid tank to pressurize the fluid tank. The pump includes a pump handle located at the bottom of the tank at one end of a rod, and a piston at the other end of the rod. A pressure-relieving air channel extends through the piston, the rod, and the pump handle to emit air out of the pump and into the environment when the fluid tank is at a maximum pressure. A pressure relief valve is disposed inside the piston to control the flow of air through the air channel. The pump handle locks against the tank using a “twist-and-lock” mechanism to remain secured in a retracted position.