Computational modelling techniques in the optimization of corrosion control for reducing lead in Canadian drinking water

Compliance modelling has been used to good effect in the optimization of plumbosolvency control in the UK and was evaluated in the Canadian and US contexts via three case studies. In relation to regulatory compliance, supplementary orthophosphate dosing could be justified in one water supply system but not in one other. Compliance modelling indicated that Health Canada's Tier 1 protocol is much less stringent than its Tier 2 protocol and that optimization based on 6+ hour stagnation samples vs 15 μg/l is likely to be more stringent than that based on 30 min stagnation samples vs 10 μg/l. The modelling of sequential sampling for an individual home indicated that sample results could be markedly affected by the length of the lead service line, by the length of the copper premise pipe and by pipe diameters. The results for sequential sampling were also dependent on flow characteristics (plug vs laminar). For either regulatory compliance assessment or for the optimization of plumbosolvency control measures, routine sequential sampling from the same houses at a normalized flow will minimize these variable effects.