Wastewater for irrigation in low- and middle-income countries can recharge aquifers and potentially contaminate supply sources. The infiltration rate has increased 13-fold in Mexico's Mezquital Valley, the largest agricultural area wastewater-irrigated worldwide, thus we assume that wastewater had contaminated supply sources. Fecal indicator bacteria (FIB) counts were enumerated in household water of two wastewater-irrigated areas, Tula and Tlahuelilpan, and a groundwater irrigated area, Tecozautla. During 2016–2017, household water, wastewater, and groundwater were sampled, analyzing fecal coliforms, fecal enterococci, and Escherichia coli, following membrane filtration procedures, and confirming the presence of E. coli by polymerase chain reaction. Nearly 50% of household water contained fecal contamination of up to 4.62 × 10⁴ CFU/100 mL. Significant differences between FIB counts in household water from Tula and Tecozautla were observed by Kruskal–Wallis and Dunnett tests. Household water samples from Tula contained highest FIB counts. Wastewater from Tula and Tlahuelilpan contained counts of six orders-of-magnitude of FIB. Counts were high when residual chlorine was <0.2 mg L⁻¹ and underwater storage. This research serves as a baseline to observe improvement with a newly installed wastewater treatment plant. Safe irrigation wastewater reuse should be performed under strict surveillance, considering human safety a priority.

低收入和中等收入国家的灌溉废水可以给含水层补水，并可能污染供应源。在全球最大的农业灌溉地区墨西哥的梅斯基塔尔山谷，渗透率增加了13倍，因此我们认为废水污染了供应源。粪便指示菌（FIB）计数在两个废水灌溉区（图拉和Tlahuelilpan）以及地下水灌溉区（Tecozautla）的家庭用水中进行计数。在2016-2017年期间，对生活用水，废水和地下水进行了采样，按照膜过滤程序分析了粪便大肠菌，粪便肠球菌和大肠杆菌，并确认了大肠杆菌的存在。通过聚合酶链反应。几乎50％的家庭用水中粪便污染高达4.62×10 ⁴ CFU / 100 mL。通过Kruskal-Wallis和Dunnett测试，观察到来自图拉和Tecozautla的家庭用水中FIB计数之间的显着差异。图拉的家庭用水样品中FIB含量最高。来自图拉和特拉韦伊尔潘的废水包含了六个数量级的FIB。当残余氯<0.2 mg L ^-1并在水下储存时，计数很高。这项研究作为观察新安装的废水处理厂的改进的基准。应将人的安全放在首位，在严格的监督下进行安全的灌溉废水回用。