Vouchers for safe water treatment in Nigeria

Last registered on August 24, 2023


Trial Information

General Information

Vouchers for safe water treatment in Nigeria
Initial registration date
August 17, 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
August 24, 2023, 4:57 AM EDT

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


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Primary Investigator

University of Michigan

Other Primary Investigator(s)

PI Affiliation
Princeton University
PI Affiliation
Chicago University

Additional Trial Information

On going
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. In certain contexts, vouchers for free chlorine solution have been shown to be (i) a cost-effective solution to target water treatment to households with the highest need and likelihood of using chlorine and (ii) an effective way of reducing diarrhea incidence and improving child health. There is much less evidence on the impacts of using vouchers for free chlorine in contexts with both limited chlorine knowledge and exposure.

To that end, we conduct a randomized controlled trial (RCT) to study the effects of offering vouchers for free chlorine in public health facilities in Northern Nigeria. Northern Nigeria possesses high rates of under 5 children mortality and disease outbreaks along with very low reported awareness of chlorine among communities. In this context, we examine the impacts of a voucher program on child health outcomes, including caretaker-reported diarrhea, fever, and cough incidence. We also examine several implementation outcomes including the rate of voucher redemption, frequency of health visits, chlorine usage rates as well as health staff acceptance and engagement. We monitor the program's impact in at least ten public health facilities in Kano State, one of the Nigerian states with the highest under 5 children mortality.

External Link(s)

Registration Citation

Dupas, Pascaline, Michael Kremer and Elisa Maria Maffioli. 2023. "Vouchers for safe water treatment in Nigeria ." AEA RCT Registry. August 24. https://doi.org/10.1257/rct.11943-1.0
Experimental Details


A program to provide, via the existing healthcare infrastructure, vouchers for a free, chlorine-based water treatment product to pregnant women and women with children under 5 years old. The research activities include:

Pregnant women and women with children under age five that visit public health facilities to seek care are eligible to receive vouchers for free chlorine at the health facility.

This study conducts individual-level randomization, assigning half of the women to receive vouchers and the other half to the control group as we enroll them.

Women in the treatment group will receive a monthly supply of vouchers for chlorine products that can be redeemed monthly until the end of the program. The program will be set up so that voucher 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 day, 7-day period, and two-week period.

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 public health facilities
Secondary Outcomes (explanation)
The 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 vouchers for free, chlorine-based water treatment products (“Treatment”) or not (“Control”).

Any pregnant woman or woman with children under five 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 five who visit our partner health facilities to seek care.” We exclude women who come to the facility only to accompany another person seeking care, or for any other reason. There are no other exclusion criteria except for women who did not consent to the study. Enumerators will be stationed in public health facilities to recruit and enroll women, with the consent and assistance of health facility staff.

Randomization and treatment
We will conduct individual-level randomization. Randomly selected women in the treatment group will receive vouchers for a free, chlorine-based water treatment product to be redeemed at the health facility each month.

Each voucher 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 vouchers or not is voluntary. When the voucher is redeemed, the health facilities workers will submit a digital redemption record. 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
Randomization will be conducted after a brief survey to enroll women in the program and collect baseline information. We will assign treatment status using a computer-based random number generation process during enrollment.
Randomization Unit
The level of randomization will be the individual.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
10 health facilities (to be potentially extended further, pending funding)
Sample size: planned number of observations
We expect on average 94 pregnant women coming for a first ANC visit per health facility and approximately 150 women coming in for revisits each month. The target number of enrollments per day is 10 women on average in each sampled health facility. We expect to enroll a couple of days per week on ANC and Routine Immunization days. We expect to enroll a minimum of 1200 women from the 10 health facilities for a 6-week enrollment. Conditional on funding, we may extend enrollment up to 12 months and/or expand to other health facilities. The total number of enrolled mothers would then increase.
Sample size (or number of clusters) by treatment arms
600 women in treatment group initially (to be potentially extended further, pending funding)
600 women in control group initially (to be potentially extended further, pending funding)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
University of Chicago Social and Behavioral Sciences Institutional Review Board
IRB Approval Date
IRB Approval Number
IRB Name
National Health Research Ethics Committee (NHREC) of Nigeria
IRB Approval Date
IRB Approval Number
IRB Name
Kano State Ministry of Health, Health Research Ethics Committee
IRB Approval Date
IRB Approval Number
SHREC 2023/3949