70年来，渥太华市一直使用生石灰（氧化钙）来提供 净化水的防腐保护。已使用8.5的处理水pH目标 将腐蚀影响降至最低，但仍会产生轻度腐蚀性的水。整齐 改善腐蚀防护，消除与腐蚀相关的操作问题 生石灰，1999年开始全面审查，以开发一种新的腐蚀剂 控制策略。 通过实验室规模和试点试验，对一些化学替代品进行了评估 确定对浊度、pH响应、氯需求、氯胺稳定性的影响， 腐蚀指数、味道和化学剂量。 使用了几个标准来比较各种腐蚀控制策略:水质 影响（健康和美学）；对工业客户的影响；法规遵从性； 运营和资本成本； 安全和环境风险；以及过程控制的影响。 根据分析结果，在pH=9.2时，建立了一种新的腐蚀控制策略，其中 最低碱度目标为35 mg/L（CaCO₃）。 在实施阶段，该市的一个老城区意外地被发现 经历高水平的铅（流动样品为0.010-0.015 mg/L）。发现 这是客户测试的结果，并得到了城市水质工作人员的确认。一 由于铅的健康问题，对300个地区的家庭进行了深入调查 接触饮用水。 发现问题的原因是内部硝化作用导致的pH值降低 分配管道。处理后的水的pH值从8.5增加到9.2，以便 抑制铅的溶解。这项操作措施比计划提前一年实施， 但立即成功地将铅值降至0.006-0.008 mg/L范围。 随后，在接下来的一年里，对几个哨兵点进行了监测，以观察季节变化 水温和硝化作用对铅暴露的影响。一些 提出了处理铅污染的类似水质事件的建议 饮用水。

For seventy years, the City of Ottawa used quicklime (calcium oxide) to provide corrosion protection in the treated water. A treated water pH target of 8.5 had been used to minimize corrosive effects, yet still resulted in water that is mildly corrosive. In order to improve corrosion protection and to eliminate operational problems associated with quicklime, a comprehensive review was initiated in 1999 to develop a new corrosion control strategy. A number of chemical alternatives were evaluated through bench-scale and pilot tests to determine impacts on turbidity, pH response, chlorine demand, chloramine stability, corrosion indexes, taste, and chemical dose. Several criteria were used to compare various corrosion control strategies: water quality impacts (health & aesthetic); effects on industrial customers; regulatory compliance; operating and capital cost; safety and environmental risk; and, process control impacts. From the analysis, a new corrosion control strategy was established at pH=9.2 with a minimum alkalinity target of 35 mg/L (CaCO₃). During the implementation phase, an old area of the City was unexpectedly found to experience high levels of lead (0.010 - 0.015 mg/L for flowing samples). The discovery came as a result of customer testing, and was confirmed by City water quality staff. An intensive investigation was initiated in 300 area homes, due to health concerns of lead exposure from drinking water. The cause of the problem was found to be pH depression induced by nitrification within the distribution piping. The pH of treated water was increased from 8.5 to 9.2 in order to suppress lead dissolution. This operational measure was taken 1 year ahead of schedule, but was immediately successful in lowering lead values to the 0.006 - 0.008 mg/L range. Several sentinel sites were subsequently monitored over the next year to observe seasonal effects of water temperature and nitrification on lead exposure. A number of recommendations are made for handling similar water quality events dealing with lead in drinking water.