这篇文章报告了美国水务公司的一项调查结果，这些水务公司使用明矾作为混凝剂，并测量了过滤水中的总铝（Al）浓度。调查结果表明，有效去除颗粒物可将残余铝水平降至最低，尤其是当原水中总铝浓度升高时。结果进一步表明，过滤后用于pH调节的石灰可能是残余铝的重要来源。包括15篇参考文献、表、图。

This article reports results of a survey of water utilities in the United States that use alum as a coagulant and have measured the concentration of total aluminum (Al) in their filtered water. Survey results suggest that effective removal of particulate matter minimizes residual Al levels, especially when raw water contains elevated concentrations of total Al. Results further indicate that lime used for pH adjustment following filtration may be an important source of residual Al. Includes 15 references, tables, figures.