Stay connected: Encouraging water service payments in Nairobi’s urban slums

Last registered on November 17, 2018


Trial Information

General Information

Stay connected: Encouraging water service payments in Nairobi’s urban slums
Initial registration date
November 13, 2018

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
November 17, 2018, 9:35 PM EST

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



Primary Investigator

World Bank

Other Primary Investigator(s)

PI Affiliation
University of Maryland
PI Affiliation
UC Berkeley

Additional Trial Information

On going
Start date
End date
Secondary IDs
Through a large-scale randomized experiment of approximately 5,500 water utility customers (landlords) we measure the direct impact of disconnection notices to non-paying customers, and the associated spillover effects on neighbors. We additionally provide tenants with information about account balances and payment behavior to test the effect of strengthening bottom-up accountability in low and high enforcement settings. The study builds on work exploring how to effectively expand the provision of basic services (water, electricity, sewerage) to low income areas when poor households are typically unable to bear the full costs of connection and use. Subsidies and/or lines of credit have been successful in increasing household-level access, but this can increase the debt burden of utilities and households if customers fail to pay. This, in turn, threatens the sustainability and incentives of utilities to expand access further. Combining limited ability/willingness to pay with weak and ad hoc enforcement mechanisms in informal settlements, where the majority of Kenya’s urban poor live, means that defaulting on monthly fees for water and sewer charges is the norm rather than the exception. The target population is customers of the utility - the Nairobi City Water and Sewer Company – who are typically landlords with properties that house multiple tenants where these landlords are primarily responsible for paying utility service charges.
External Link(s)

Registration Citation

Coville, Aidan, Sebastian Galiani and Paul Gertler. 2018. "Stay connected: Encouraging water service payments in Nairobi’s urban slums." AEA RCT Registry. November 17.
Former Citation
Coville, Aidan, Sebastian Galiani and Paul Gertler. 2018. "Stay connected: Encouraging water service payments in Nairobi’s urban slums." AEA RCT Registry. November 17.
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Experimental Details


Nairobi Water field staff (Community Development Agents, or CDAs), together with the utility’s finance team will be responsible for outreach and disconnections.
Control: All customers in the sample will be provided the following base intervention delivered by CDAs (in sequence): (i) A phone call to the landlord / owner to collect up-to-date contact information, provide basic information on how to read meters and pay bills, and share their latest account balance on record; (ii) an on-site meter reading; and (iii) an SMS to landlords/owners providing the account balance based on the meter reading.
Treatment 1: A subset of compounds will receive a face-to-face visit from a CDA informing tenants about the current balance, how payments can be made, and the importance of ensuring the landlord makes payment to avoid having services disconnected.
Treatment 2: After the first round of outreach, a subset of compounds that remain in arrears will be provided official notification and given approximately 15 days to make payment or have their services disconnected. Official communication includes (in order): (i) a notice posted to the compound door warning customers of disconnection if payment is not made by a specified deadline, and providing a contact number for coordinating a payment arrangement or disputing bill; (ii) an SMS providing a second warning; and (iii) a third and final warning provided through a phone call made to landlords alerting them to pay within 48 hours or be disconnected. Compounds that do not make payment in this time will then be disconnected. Reconnection would be at the landlord/owner’s expense, and only after paying their outstanding service charges in full.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Proportion of customers making a payment for water/sewer charges
Proportion of outstanding service charges paid post-intervention
Total amount (in Kenyan Shillings) paid by customer post-intervention
Primary Outcomes (explanation)
Data used to measure outcomes will come from utility administrative billing data and will be measured 1, 3 and 6 months post-intervention to assess short and medium-term impacts

Secondary Outcomes

Secondary Outcomes (end points)
Customer total service charge balance
Number of post-intervention meter readings conducted by customer
Average monthly water usage
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The identification strategy relies on a cluster-randomized experiment. All informal settlement customers in Nairobi Water’s utility database will first be called to confirm contact details and receive the base intervention. Eligibility criteria into the study will include: (i) customers can be contacted and their contact details can be updated; and (ii) customers do not hold multiple accounts (multiple property owners) – which is expected to yield an eligible sample size of approximately 5,500 customers. After the base intervention has been implemented and contact details have been updated, all compounds with tenants (approximately 2600 customers) will be randomly assigned to receive face-to-face tenant sensitization (Treatment 1). Randomization will be stratified by location (settlement), whether landlord resides in the property, and whether the landlord has ever made a payment. After completion of the outreach campaigns, all customers in the study will be grouped into clusters which will reflect the street they live on (approximately 166 clusters). Half of the clusters will be randomized into treatment and half into control, stratified by settlement and cluster size. Within treatment clusters, half of all compounds eligible for disconnection based on their balance and repayment history, will be randomly assigned to receive disconnection notices, resulting in approximately 420 compounds receiving notices and subsequently disconnected if they fail to make payment. To test for direct effects of receiving disconnection notices, we will compare disconnection treatment customers in treatment clusters to disconnection-eligible customers in control clusters. To test for spillovers, we will compare repayment rates of control customers in treatment clusters to disconnection-eligible customers in control clusters. To test the effectiveness of bottom-up accountability through increased tenant pressure in low and high enforcement settings, we will compare compounds with tenants that receive treatment 1 (tenant sensitization) to compounds with tenants that don’t receive the treatment, in disconnection vs. non-disconnection clusters, effectively estimating the interaction effect size of treatments 1 and 2.
Experimental Design Details
Randomization Method
Computer-based using Stata
Randomization Unit
Customer-level randomization of tenant information campaign. Cluster-level randomization of disconnection streets, followed by customer-level randomization of disconnection notices within treatment streets.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
166 clusters (streets)
Sample size: planned number of observations
5500 customers / compounds
Sample size (or number of clusters) by treatment arms
Overall sample: 5500 compounds, of which 2600 have tenants.
Treatment 1 (tenant sensitization): 1300 treatment; 1300 control
Treatment 2 (disconnection notice): 166 clusters – 83 control and 83 treatment. Within treatment clusters, 420 disconnection-eligible customers randomly assigned to treatment and an equal number assigned to control.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Outcome considered: Proportion of service charges paid At baseline 1.5% of the total invoice amount over the past 3 months had been paid on average, with a standard deviation of 14% (for disconnection-eligible compounds). MDE calculations use 80% power and alpha =0.05 as parameter inputs. For clustered analysis (disconnections) we estimate a rho of 0.032. MDEs for different tests using above assumptions: Tenant face-to-face sensitization (treatment 1) vs. no tenant intervention: 2 percentage points increase Direct effect of disconnection notice (treatment 2): 2.5 percentage points increase Indirect effect of disconnection notice (adjacent clusters vs. non-adjacent clusters): 2.5 percentage points Interaction between face-to-face sensitization (treatment 1) and disconnection notice (treatment 2): 4 percentage points

Institutional Review Boards (IRBs)

IRB Name
Innovations for Poverty Action
IRB Approval Date
IRB Approval Number
IRB Name
Maseno University Ethics Review Committee
IRB Approval Date
IRB Approval Number


Post Trial Information

Study Withdrawal

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials