Household water security is a mediator of household food security in a nationally representative sample of Mexico.

Objective: Explore the relationship between water insecurity (WI) and food security and their covariates in Mexican households.

Design: A cross-sectional study with nationally representative data from the National Health and Nutrition Survey-Continuous 2021 (in Spanish, ENSANUT-Continua 2021), collected data from 12 619 households.

Setting: WI was measured using the Household Water Insecurity Experiences (HWISE) Scale in Spanish and adapted to the Mexican context. Food security was measured using the Latin American and Caribbean Food Security Scale. A generalised path model was used to produce two simultaneous logistical regression equations - WI (HWISE ≥ 12) and moderate-to-severe food insecurity (FI) - to understand key covariates as well as the contribution of WI to FI.

Participants: The head of the household, an adult of >18 years of age, consented to participate in the survey.

Results: Households experiencing WI were more likely to experience moderate-to-severe FI (OR = 2·35; 95 % CI: 2·02, 2·72). The odds of WI were lower in households with medium (OR = 0·74; 95 % CI: 0·61, 0·9) to high (OR = 0·45; 95 % CI: 0·37, 0·55) asset scores. WI also depended on the region of Mexico. FI is more prevalent in indigenous people (OR = 1·29; 95 % CI: 1·05, 1·59) and rural households (OR = 0·42; 95 % CI: 1·16, 1·73). Notably, wealth and household size did not contribute directly to FI but did so indirectly through the mediating factor of WI.

Conclusions: Our study shows that there are structural factors that form part of the varied determinants of WI, which in turn is closely linked to FI.