Long-term discolouration modelling for cast iron mains

Water companies have been working to introduce strategies to reduce discolouration customer contacts via non-specialist ‘business as usual’ practices. A greater understanding of discolouration material behaviour, however, is still needed to accurately inform the mobilisation response and regeneration rates in mains of different materials. The Variable Condition Discolouration Model (VCDM) that tracks both accumulation and mobilisation processes has been validated in some pipe materials using long-term time series data. This paper investigates calibration for a 15 km cast iron (CI) main, using daily turbidity responses with VCDM parameter sensitivity and temporal stability investigated using a statistical approach comparing three periods of the data. Results highlight the VCDM as widely applicable to determine long-term discolouration behaviour and improve behavioural understanding. In this case, analysis of different time periods indicates flow-conditioning not only improves network resilience but can also reduce mobilisation rates and discolouration risk