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Latrines are an effective way for people in low- and middle-income countries to move away from open defecation. Guidelines are used to provide a recommended horizontal setback distance from a latrine to a downgradient well to ensure the safety of the well from subsurface contaminants. We collected 107 journal papers, books, and reports to critically review the recommended setback distances and how these recommendations are derived. It was discovered that the four most common guidelines/reviews are all based principally on just four field studies, all of which were conducted over 40 years ago, which casts doubt on a frequently used one-size-fits-all approach. More recent methods for latrine siting use both field data and some sort of modeling component to account for the different site conditions, but these models have not been verified for use outside their respective studies. They are also limited in how they consider the hydraulic connection between the latrine and the well. We recommend that future siting guidelines should focus more on vertical separation, include chemical contamination, and be based on models describing how latrines and wells are hydraulically connected, along with the fate and transport of potentially harmful contaminants.

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厕所是低收入和中等收入国家人们摆脱露天排便的有效途径。指南用于提供从厕所到下坡井的建议水平退缩距离，以确保井的安全免受地下污染物的影响。我们收集了 107 篇期刊论文、书籍和报告，以批判性地审查建议的后退距离以及这些建议是如何得出的。结果发现，四种最常见的指南/评论都主要基于四项实地研究，所有这些研究都是在 40 多年前进行的，这对经常使用的一刀切的方法产生了怀疑。最近的厕所选址方法使用现场数据和某种建模组件来解释不同的场地条件，但这些模型尚未在各自的研究之外使用得到验证。他们对厕所和水井之间的水力连接的考虑也受到限制。我们建议未来的选址指南应更多地关注垂直分离，包括化学污染，并基于描述厕所和水井如何液压连接的模型，以及潜在有害污染物的归宿和运输。