A purchases a spa bath and has it installed in her house. The installation is properly carried out by a qualified plumber and electrician, in accordance with the manufacturer's instructions. When A uses the spa for the first time, she finds that the jets of water are uncomfortably strong. She reads the manual that is provided with the bath and discovers that there is a lever near the taps that can be used to adjust the flow through the jets. She moves the lever backwards in the correct direction, but it has no effect until she moves it fully back, at which point the pump suddenly goes into reverse and the water begins draining out of the spa through the jets at high speed, creating a powerful suction. A's leg is sucked up against a jet and by the time she manages to switch off the motor, she has suffered a serious injury. Subsequent testing shows that the flow adjustment lever can malfunction in this way one time in ten.