Ranking pipes in water supply systems based on potential to cause discoloured water complaints

A novel concept to rank pipes based on the potential (risk) to cause discoloured water complaints when broken is presented. A fixed re-suspension velocity for all sediments was used previously to model sediment transport. However, there is always a risk of sediment re-suspension and discoloration, if the velocity caused by hydraulic disturbance is greater than the conditioning velocity- the maximum daily velocity historically experienced in a pipe before the disturbance. In a full scale system, five pipes of different diameters (99 - 222 mm) and locations (loop or open) were simulated to break (break main flow at 10L/s) and the hydraulic response was analysed using hydraulic software. The total affected length of the pipes where velocity was more than the conditioning velocity was used for ranking. In general, breakage of a smaller diameter pipe (100 mm diameter) caused more widespread disturbance. If proven in the field, the hydraulic software could be modified to rank pipes, making it easy for utilities to prioritise the pipe to replace or pay more attention