Nolkup: an app to access low arsenic water in Bangladesh

Last registered on March 10, 2025
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Pre-Trial

Trial Information

General Information

Title
Nolkup: an app to access low arsenic water in Bangladesh
RCT ID
AEARCTR-0015469
Initial registration date
March 07, 2025

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 10, 2025, 9:37 AM EDT

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

Locations

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Primary Investigator

Name
Alexander van Geen
Affiliation
Lamont-Doherty Earth Observatory of Columbia University
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Other Primary Investigator(s)

PI Name
Jack Willis
PI Affiliation
Columbia University
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PI Name
Prabhat Barnwal
PI Affiliation
Michigan State University
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Additional Trial Information

Status
In development
Start date
2025-03-01
End date
2026-03-15
Keywords
Behavior, Environment & Energy, Health
Additional Keywords
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Chronic exposure to arsenic from drinking well water that is elevated in arsenic accounts for 5% of total mortality in Bangladesh, reduces intellectual and motor function in children, and has been shown to reduce household earnings by 9% per person exposed. Arsenic concentrations in well water vary geographically and with the depth of the well, but usually not over time. A neighboring well or a deeper new well can often reduce arsenic exposure dramatically. In this trial, we will disseminate georeferenced data from a government-run well testing for arsenic program with an interactive web application. The objective is to assess whether increasing awareness about arsenic contamination of wells and provision of information about the depth distribution of arsenic with this app encourages households to reduce their exposure by switching to a neighboring low arsenic well or installing their own deeper well.
External Link(s)

Registration Citation

Citation
Barnwal, Prabhat, Alexander van Geen and Jack Willis. 2025. "Nolkup: an app to access low arsenic water in Bangladesh." AEA RCT Registry. March 10. https://doi.org/10.1257/rct.15469-1.0
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Experimental Details

Interventions

Intervention(s)
This intervention is conducted in the aftermath of a government-run well program in Bangladesh that tested over 6 million wells for arsenic during 2021-23. We deploy an interactive web application that relies on a subset of well-test data collected in this program. Once the current primary drinking water well tests high for arsenic, there are two main mitigation options available to households. A short-term option is to switch to a neighboring well that is low in arsenic. In many but not all villages, a more permanent option is to install a new well to the 150-300 depth range where the aquifer is likely to be low in arsenic.

For this intervention, we selected 100 villages where the overall proportion of high-arsenic wells ranges from 20 to 85% and the proportion of low-arsenic wells in the 150-300 ft depth range is between 0 and 25%. After dividing the 100 villages in two strata based on the proportion of low- and high-arsenic wells, a random subset of 25 intervention villages from each strata will be drawn at a public lottery. Flyers in the shape of triangular table-top 2025 calendar will be handed out in all 100 villages with maps of the proportion of high arsenic wells across the country spanning 20 years, the message that continued chronic exposure to arsenic increase mortality, along with an encouragement to seek a low arsenic well if recent government testing indicated a high arsenic concentrations in the reader’s own well.

Flyers in the subset of 50 intervention villages will in addition show a map of the local distribution of arsenic in wells in the <150, 150-300, and >300 ft depth intervals, a QR code and a link to the interactive web application, another QR code to a YouTube video with instructions, and an encouragement to consider installing a new well in the 150-300 ft range to lower arsenic exposure. Phone numbers will be collected at a busy location in all intervention villages in order to be able to send reminders by SMS along with a link to the web application. One year after the intervention, a subset of 40 households per village in all 100 villages will be randomly selected from a government list of high arsenic well owners to ask about risk perception concerning arsenic, perceived arsenic status of the current well, and if a household either switched to an existing or installed a new low arsenic well.
Intervention Start Date
2025-03-15
Intervention End Date
2026-03-15

Primary Outcomes

Primary Outcomes (end points)
Whether household with a high-arsenic well switched to a another well source since the intervention (binary)
Whether household with a high-arsenic well switched to an existing perceived to be low in arsenic since the intervention (binary)
Whether the household installed a new well since the intervention (binary)
Whether the household installed a new well since the intervention to the 150-300 ft depth range (binary)
Depth of any new well installed by household since the intervention (continuous)

Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Perception of health risk posed by arsenic in well-water (Likert scale)
What proportion of wells are low arsenic in this village? (proportion)
What proportion of wells within <150ft deep are low arsenic in this village? (proportion)
What proportion of wells in 150-300 ft depth range are low arsenic in this village? (proportion)
What is the minimum safe well depth with respect to arsenic risk in this village? (ft)
Awareness of the web application (binary)
Managed to use the web application (binary)
Whether the household discussed the existence of low-arsenic wells in the village with neighbors (binary)
How easy it is for a household to take water from a neighbor owning a low-arsenic well (Likert scale)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
No baseline survey will be conducted but we have the names and phone numbers from government listing of owners of high arsenic wells. The in-person follow up will target a random sample of up to 40 owners of a high arsenic well per village. We will compare the proportion of high arsenic well owners that switched to an existing low arsenic well or installed a new low arsenic well in the 50 treatment villages compared to the 50 control villages that were not provided with local arsenic data with the web application.

Experimental Design Details
Not available
Randomization Method
Randomization is conducted using an urn with numbered ping-pong balls in person at a local government office in the presence of civil servants and journalists.

Randomization Unit
The unit of randomization is the village.
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
100 villages
Sample size: planned number of observations
40 households per village x 100 villages = 4,000 households split evenly between treatment and control.
Sample size (or number of clusters) by treatment arms
50 control village control, 50 intervention villages
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Columbia University IRB
IRB Approval Date
2024-03-05
IRB Approval Number
IRB-AAAT7989
Analysis Plan