Safe Drinking Water at Home: Evidence from a randomised trial in Uganda

Last registered on November 27, 2023


Trial Information

General Information

Safe Drinking Water at Home: Evidence from a randomised trial in Uganda
Initial registration date
February 23, 2023

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
March 08, 2023, 11:26 AM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Last updated
November 27, 2023, 9:35 AM EST

Last updated is the most recent time when changes to the trial's registration were published.


There is information in this trial unavailable to the public. Use the button below to request access.

Request Information

Primary Investigator

Ghent University

Other Primary Investigator(s)

PI Affiliation
Ghent University
PI Affiliation
Mountains of the Moon University

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Point-of-use (POU) drinking water treatment plays a crucial role in overcoming the health burden associated with waterborne diarrheal disease in low and middle-income regions. This study focuses on the long run impacts of three POU water treatments – boiling on a cook stove, ceramic filtration, and membrane filtration– in two districts of Uganda. We analyse the sustained use of the cook stove and the filters, and the impact on microbiological water quality at POU, diarrhoeal disease and household savings in the course of 18 months. A total of 600 households are involved in this randomised controlled trial. 450 households receive one of the three treatments and training on its adequate usage. 150 households are assigned to the control group. Data collection involves household surveys and water sample analysis during a baseline and four follow-ups. Focus group discussions at baseline and at end line gather an in-depth understanding of the results.
External Link(s)

Registration Citation

Maes, Femke, Bart Defloor and Violet Kisakye. 2023. "Safe Drinking Water at Home: Evidence from a randomised trial in Uganda." AEA RCT Registry. November 27.
Sponsors & Partners

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information
Experimental Details


The intervention consists of the random distribution of three different water treatment methods over the selected treatment population and training in its correct use. The treatments are an improved cook stove to boil water, ceramic filtration and membrane filtration. Each drinking water filter is accompanied by a leaflet with instructions on the use and maintenance needs. The drinking water filters and cook stoves are distributed to the dwellings of the selected households by members of HEWASA and Kiima foods, with the help of local guides of the Village Health Teams (VHTs). Members of HEWASA provide individual training at the dwelling of the responsible household members in use and maintenance of the assigned water treatment method.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
1. Drinking water quality
2. Diarrhoeal disease
3. Uptake
4. Household savings
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.

Secondary Outcomes

Secondary Outcomes (end points)
1. Drinking water quality
2. Diarrheal disease
3. Uptake
4. Household savings
Secondary Outcomes (explanation)
1. Apart from the primary outcomes TTC, E.coli and turbidity for drinking water quality at home, secondary outcomes are considered. First, households will be asked about their primary water source. These choices could change due to seasonal availability of water, but also because of the intervention. For instance, receiving a water filter could induce households to fetch water at more turbid sources closer to the home. We survey whether there is a qualitative change in the nature of the source (well, borehole etc.). Next, we analyze a water sample of each indicated source on the same characteristics as outlined above to determine potential changes in source water quality over the course of the intervention.
3. As a secondary outcome, the respondent will be asked whether a household member drank unfiltered or non-boiled water in the previous day. If this is the case, the respondent will be asked whether another method was used or whether the water was left untreated. Reasons addressed by the responsible household member will be recorded. This measure of adherence to treated water also will be reported binary, and separately for children below five, children above five and adults. All reasons addressed for not drinking treated water will be listed and thematically ordered.

4. As secondary outcomes, the indirect savings in resources and time due to lower health care expenses and less absent days at school or work because of diarrhea will be recorded. The respondent will be surveyed about medical expenditures and the absence from usual activities of children and adults due to diarrhea in the previous seven days. The first will be reported in monetary terms as outlined above, while the latter will be reported in number of days.

Experimental Design

Experimental Design
Experimental evidence to answer the four research questions will be obtained by a four-arm randomized controlled trial over an 18-month period. The trial will include three treatment groups that each receive either a cook stove for energy efficient boiling, the ceramic filter or a membrane filter, and one control group that continues business as usual. The RCT design allows to identify and compare the long run causal impacts of the three treatments on uptake, microbiological water quality, diarrheal disease among young children and household time and money savings. Data will be obtained by a baseline survey and four follow-up surveys, accompanied by drinking water quality analysis at point of source and point of use. The treatment will be phased-in i.e., all households in the control group will receive a water filter at the end of the experiment.
Experimental Design Details
Not available
Randomization Method
The randomization is done per strata, which is in this study the two districts of interest. All eligible households in the two districts are randomly assigned to the four trial arms (boiling, ceramic filter, membrane filter and business as usual) with an assignment rate of 25% in each arm. The study arms are non-overlapping arms. The randomization is done by means of the random number generator in Stata 17.
Randomization Unit
Randomization is done at household level. This is individual randomization for the outcomes drinking water quality, uptake and household savings. This is group level randomization for the outcome diarrheal disease, since a household often counts multiple children below five years.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
The households can be considered as clusters for the outcome diarrheal disease (for reasons outlined above).
600 households are involved in this study.
Sample size: planned number of observations
600 households and approximately 900 children under five years.
Sample size (or number of clusters) by treatment arms
The four treatment arms all contain 150 households and approximately 300 children.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
The following power calculations are calculated based on the means and variances at baseline in the data. 600 households evenly divided over four treatment arms account for a minimal detectable effect size of 53 CFUs reduction in E.coli, 61 CFUs reduction in TTC and 13 NTUs reductions in turbidity. The standardized minimal detectable effect size is 0.36. Variables Mean SD MDE MDE standardized MDE as percentage of the mean E.coli 61.237202 146.89854 52.698715 .35874227 .86056703 TTC 105.51195 170.16864 61.04668 .35874227 .57857603 Turbidity 13.035959 36.064888 12.938 .35874227 .99248546 900 children under five evenly divided over four treatment arms account for a minimal detectable effect size of 0.13 in diarrheal disease incidence in the past seven days. The standardized minimal detectable effect size is 0.32. Variables Mean SD MDE MDE standardized MDE as percentage of the mean Diarrhea incidence .23825504 .42625439 .13466863 .31593487 .56522894 The estimated effect sizes are rather conservative as they already account for 5% non-compliance in the treatment group and 10% attrition. Moreover, these calculations do not apply to the pooled estimator over the four follow up rounds. The pooled estimator will have higher power stemming from the multiple rounds of post-treatment data collection, as suggested by McKenzie (2012).
Supporting Documents and Materials

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information

Institutional Review Boards (IRBs)

IRB Name
Ethics committee of the Faculty of Economics and Business Administration
IRB Approval Date
IRB Approval Number
UG-EB 2023 B
Analysis Plan

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information