水井和肠道疾病传播试验（WET - 试验）

Inclusion Criteria:

1. Household must rely on a private groundwater supply (private well or spring)
2. Child must be over six months and under 4 years old at enrollment so that they will be under five years of age for the duration of the 12-month study period.
3. >75% of the water the child consumes must be tap water untreated by any treatment device capable of microbial water treatment. Proportion is estimated by the parent and includes water used to make juice or formula.
4. Child must be a full-time resident of the home, defined as living in the home for five or more days every week. The intervention is administered at the household level; therefore the child must reside at home and be regularly exposed to the intervention.

Exclusion Criteria:

1. Child has a chronic, gastrointestinal condition (e.g., Crohn's disease), which may complicate differentiation between signs and symptoms of gastrointestinal illness associated with drinking water and those of the pre-existing condition.
2. Child is immunocompromised, which may result in increased susceptibility to waterborne illness. Daily oral steroids also considered an exclusion criteria due to their associated immunosuppressive effects.
3. Parents are unable to submit data through short message service (SMS) text messages (smartphone was not required).
4. Household treats their water for microbiological contamination at point-of-entry or point-of-use.

In the case where multiple children met the eligibility criteria, the youngest eligible child was enrolled. Records were maintained on the recruitment process documenting reasons for eligibility and those that declined to participate in the study.