Latar Belakang: Data Studi Status Gizi Indonesia (SSGI) tahun 2021 menunjukkan prevalensi Balita stunting di Indonesia sebesar 24,4%. Kabupaten Lumajang urutan ke-4 prevalensi tertinggi stunting sebesar 30,1% di Jawa Timur. Kasus diare juga meningkat dalam 4 tahun terakhir dan merupakan penyebab mortalitas terbanyak pada bayi. Tujuan penelitian adalah untuk menganalisis hubungan kualitas air konsumsi, higiene, dan sanitasi rumah tangga dengan kejadian stunting di Kabupaten Lumajang.Metode: Penelitian kuantitatif dengan desain studi kasus-kontrol. Populasi seluruh rumah tangga Balita stunting dan non stunting usia 25-59 bulan di Kabupaten Lumajang. Penelitian dilaksanakan pada bulan Juli sampai Agustus 2022 di Puskesmas Rogotrunan, Tekung, Sumbersari, Gucialit, Padang, Bades, Kedungjajang, Klakah. Pengambilan sampel dengan proportional stratified random sampling menghasilkan 82 responden (masing-masing 41 pada kelompok kasus dan kontrol). Analisis dengan uji bivariat chi-square.Hasil: Balita stunting dengan berat badan kurang memiliki riwayat diare berulang lebih banyak daripada Balita non stunting. Kualitas air konsumsi pada kelompok kasus dan kontrol tidak berbau, tidak berwarna, dan tidak berasa. Praktik BABdi sungai pada kelompok kasus (19,5%) lebih banyak dari kelompok kontrol (4,9%). Analisis bivariat berat badan balita berhubungan signifikan dengan kejadian stunting (p-value 0,001, contingency coefficient 0,508) sedangkan kualitas air konsumsi (p-value 1,000), higiene (p-value 0,286), dan sanitasi rumah tangga (p-value 0,196) tidak berhubungan dengan kejadian stunting. Praktik BAB dalam indikator higiene rumah tangga berhubungan signifikan dengan kejadian stunting (p value 0,043, contingency coefficient 0,218).Simpulan: Indikator berat badan dan praktik BAB menjadi faktor risiko penyebab diare pada balita stunting usia 25-59 bulan di Kabupaten Lumajang. ABSTRACT Title: Relationship of Consumable Water Quality, Hygiene, and Household Sanitation with Stunting Incidence (Case Control Study on Stunting Toddlers in Lumajang District)Background: : Data from the 2021 Indonesia Nutrition Status Study (SSGI) shows that the prevalence of stunting among children under five in Indonesia is 24.4%. Lumajang Regency ranks 4th with the highest prevalence of stunting at 30.1% in East Java. Cases of diarrhea have also increased in the last 4 years and are the most common cause of infant mortality. The aim of this study was to analyze the relationship between the the quality of drinking water, hygiene, and household sanitation and the incidence of stunting in Lumajang Regency.Method: Quantitative study with a case-control study design. The population of all stunted and non-stunted toddler households aged 25–59 months in Lumajang Regency. The research was carried out from July to August 2022 at the Rogotrunan Health Center in Tekung, Sumbersari, Gucialit, Padang, Bades, Kedungjajang, and Klakah. Sampling by proportional stratified random sampling yielded 82 respondents (41 each in the case and control groups). Analysis with a chi-square bivariate test.Result: Stunted toddlers with low body weight have a higher history of recurrent diarrhea than non-stunted toddlers. The quality of the drinking water in the case and control groups was odorless, colorless, and tasteless. The practice of defecating in the river in the case group (19.5%) was more common than in the control group (4.9%). Bivariate analysis of under-five weight was significantly related to the incidence of stunting (p-value 0.001, contingency coefficient 0.508), while the quality of drinking water (p-value 1.000), hygiene (p-value 0.286), and household sanitation (p-value 0.196) were not related to stunting. The practice of defecation in household hygiene indicators is significantly related to the incidence of stunting (p-value 0.043, contingency coefficient 0.218).Conclusion: Weight indicators and bowel habits are risk factors for causing diarrhea in stunted toddlers aged 25–59 months in Lumajang Regency.