对1979年发生的三次水传播疾病暴发的研究表明，可以确定导致暴发的问题，并与多重屏障概念中保护系统的崩溃有关。设计师、公用事业人员和监管机构都有责任维护必要的保护系统的完整性，以确保提供安全的饮用水。给出了宾夕法尼亚州布拉德福德市和亚利桑那州哈瓦苏湖市的案例研究。包括9个参考文献、表格、图表。

A study of three waterborne disease outbreaks that occurred in 1979 shows that problems contributing to the occurrence of outbreaks can be identified and related to a breakdown of protective systems in the multiple barrier concept. Designers, utility personnel, and regulatory agencies share a responsibility for maintaining the integrity of the protective systems necessary to ensure the delivery of a safe and potable water. Case studies of Bradford, Pennsylvania and Lake Havasu City, Arizona are given. Includes 9 references, tables, figures.