Ms Margaret Attridge:

There would be a number of alarms in treatment plants so if one alarm failed there would be another alarm some place on the system. We would not normally rely on one chlorine alarm, for example, exiting a treatment plant. There would be a number of them on the network. Similarly, high turbidity levels would be another of our critical alarms because turbidity interferes with the disinfection process so if the turbidity alarm fails it will impact on chlorination and trigger an alarm on that. Each alarm is supported by other alarms on the system.