Primary Outcomes (explanation)
1. The participating households will be asked to identify the main drinking water container in the dwelling and a water sample will be taken from the designated water container. To assess the microbiological improvements in drinking water quality, household water samples will be analysed in the lab on the presence of total thermotolerant coliforms (TTC), and in particular the bacterium E.coli. The assessment will be performed using the membrane filtration technique on membrane lauryl sulphate medium. The unit of measurement is Colony Forming Units (CFU). A second aspect of water analysis is turbidity, i.e. a measure for the presence of particles in the drinking water. The unit of analysis is Nephelometric Turbidity Units (NTU). The values of TTC, E.coli and turbidity will both be reported in levels (CFU/NTU).
2. Diarrheal disease will be measured by recording cases among children below five years of age. A diarrhea case is defined according to the WHO-definition as “three or more loose stools passed within 24 hours, or more frequently than is normal for the individual''. The primary outcomes of diarrheal disease will focus both on incidence and longitudinal prevalence. The method is therefore twofold. First, the female household head will be surveyed on diarrhea cases in the previous seven days among children under five years of age at each follow-up wave. Second, each household will be provided with a diary to indicate whether a child experienced diarrhea on a daily basis. These diaries will be collected by the VHTs every two weeks before or after religious meetings. The outcome of interest ‘diarrhea’ will be obscure to the target population, as the relevant symptom diarrhea will be added to a list of other symptoms such as fever and cough both for the survey and the diary method (see also Performance and expectancy biases, p.14). The incidence outcomes will be reported binary by addressing whether a child had diarrhea in the previous seven days. The longitudinal prevalence will be reported as a continuous variable indicating the number of days with diarrhea between the survey waves and over the full 18-month period.
3. At each household visit the enumerators observe whether the water storage container or filter contains treated drinking water, a possible objective indicator of filter use (Rosa et al., 2014). Furthermore, the self-reported use of the cook stove and the drinking water filter will be surveyed. The respondent responsible for the cook stove or the filter will be asked when water treatment was last applied. If the treatment method is no longer being used or has broken down (irreversibly clogged, damaged etc.), the time it went out of service will be recorded. The objective and subjective use of the filter will both be expressed binary, respectively based on the presence of (treated) water and the reported use in the previous day (or today).
4. To address financial savings due to water filtration or energy efficient boiling, all respondents will be surveyed on the household expenses for charcoal, firewood or other fuels used for the treatment of drinking water or cooking in the previous seven days. Since households could receive charcoal, firewood or other fuels from relatives, they will also be questioned on the amount of each consumed in the previous seven days. Additionally, 40 households receiving the cook stove will be closely monitored during one week at each follow-up to weigh the exact amount of wood fuel used for boiling. The total monetary value will be both expressed in the local currency Ugandan Shilling and converted to US Dollar. If a household collects firewood for free from the surrounding bushes, the time spent to collect firewood in the previous seven days will be estimated by multiplying the number of roundtrips with the average timespan needed to collect firewood. The time saved will be expressed in hours.