Scaling up coupons for safe water treatment in Kenya

Last registered on January 23, 2023


Trial Information

General Information

Scaling up coupons for safe water treatment in Kenya
Initial registration date
January 19, 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
January 23, 2023, 6:36 AM EST

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


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Primary Investigator

Stanford University

Other Primary Investigator(s)

PI Affiliation
University of Chicago
PI Affiliation
University of Michigan
PI Affiliation
University of Chicago
PI Affiliation
Kenya Medical Research Institute (KEMRI)

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Guaranteeing access to safe drinking water is still a challenge in rural households in developing countries, and unsafe water sources are responsible for millions of deaths each year around the world. Coupons for free dilute chlorine solution are (i) a cost-effective solution to targeting water treatment for households that need it and will use it and (ii) an effective way of ameliorating child health and reducing diarrhea incidence. It is still an empirical challenge, however, to see if the positive health effects will be maintained when the program is implemented at scale. In this study, we conduct a randomized controlled trial (RCT) to study the impacts of a chlorine coupon program implemented at health clinics on child health, including self-reported diarrhea, fever, and cough incidence in the previous two weeks. We further investigate the pathway of the impact, such as self-reported and objectively measured use of chlorine and frequency of visits to health clinics. We monitor the program's impact at Health and Demographic Surveillance Systems (HDSS) sites in collaboration with the Kenya Medical Research Institute (KEMRI). Data collection includes child mortality, as well as verbal autopsies for deceased children. Data on mortality will be useful for future meta-analyses that pool data from multiple studies in order to estimate the mortality impact of free chlorine distribution schemes.
External Link(s)

Registration Citation

Dupas, Pascaline et al. 2023. "Scaling up coupons for safe water treatment in Kenya." AEA RCT Registry. January 23.
Sponsors & Partners

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Experimental Details


Our study proposes to conduct a coupon program for free chlorine. The research activities include:

Pregnant women and women with children under age two that visit health facilities will be eligible to receive coupons for free chlorine at the health facility.

This study will conduct individual randomization, assigning half of the women to receive coupons and the other half to the control group as we enroll.

Households with women in the treatment group will receive a monthly supply of coupons for chlorine products until the end of the program. The program will be set up so that coupon redemption can be monitored in real-time using digital redemption records. The incoming data allows the program implementer to identify individuals with low redemption rates and potentially target those for information interventions.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Verified chlorine usage, Child morbidity.
Primary Outcomes (explanation)
Verified chlorine usage: Presence of free chlorine residual in the drinking water, as observed through water testing using chlorine test strips. Households with a non-zero concentration of residual chlorine are considered to have treated their water.
Child morbidity will include caregiver-reported diarrhea, fever, and cough incidents in the previous two weeks.
The data will be collected every six months by HDSS household survey. Note: This study will be underpowered to detect impacts on mortality, but we will be collecting data on mortality in any case as this study will contribute to a meta-analysis conducted in the future.

Secondary Outcomes

Secondary Outcomes (end points)
Self-reported water treatment
Self-reported attendance at health clinics
Secondary Outcomes (explanation)
The HDSS household survey will ask households whether their current drinking water was treated with chlorine. We will also analyze other health behaviors to understand the pathway of the health impact.

Experimental Design

Experimental Design
Women enrolled in the study will be randomly assigned to receive free chlorine coupons (“Treatment”) or not (“Control”).

Any pregnant woman or woman with children under two years old visiting the health facility will be enrolled in the program. The inclusion criteria of this study are “any pregnant women or women with children under age two who visit our partner health facilities who reside in HDSS catchment areas.” There are no exclusion criteria except for women who did not consent to the study. A list of eligible women, including names or phone numbers and other information in the health facility registry, will be compiled based on health facility registers on a daily or weekly basis. The list will be sent to the research team using an encrypted data collection system. Trained enumerators will make phone calls to eligible women to enroll them in the program if they consent to participation.

Randomization and treatment
We will conduct household-level randomization. Randomly selected women in the treatment group will receive coupons for free chlorine solutions to be redeemed at the health facility each month.

Each coupon can be redeemed at the health facility each month for a one-month supply of chlorine products. Whether women or other household members will come to health facilities to redeem coupons or not receive chlorine solutions is voluntary. When the coupon is redeemed, the health facilities workers will submit a digital redemption record. Coupons in a packet will be signed to confirm the monthly redemption to the beneficiary. With the data gathered, it will be possible to compare how many products are procured in each health facility and how many are given to households.
Experimental Design Details
Not available
Randomization Method
We will assign treatment status using a computer-based random number generation process during enrollment.
Randomization Unit
The level of randomization will be the household.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
We expect about 16,000 households with children under age two or pregnant mothers in HDSS sites.
Sample size: planned number of observations
Although our enrollment criteria target children under age 2 at the time of the enrollment (given that the oldest children become age 5 at the end of the three years program), we will collect the morbidity information of any children under age 5 when the household is interviewed. We expect about 1.3 eligible children from the average household. Therefore, there are around 20,800 children under the age of 5 at HDSS sites. The final sample size for the analysis depends on how many women come to the health facility during our enrollment period. We aim to have a sample of at least 3,468 under the age 5 children to be sufficient for the analysis.
Sample size (or number of clusters) by treatment arms
1,734 children in the treatment group
1,734 children in the control group
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
University of Chicago
IRB Approval Date
IRB Approval Number
IRB Name
Kenya Medical Research Institute SERU
IRB Approval Date
IRB Approval Number