Behavioural Nudges for Water Conservation: Experimental Evidence from Cape Town

The City of Cape Town has been working with EPRU to find an evidence-based answer to which methods are most effective in encouraging more prudent water use by the public. Prof Martine Visser, Dr Kerri Brick, and Johanna Brühl are behavioural economists at EPRU. The EPRU team was supported by Samantha De Martino from Sussex University, and Jorge Garcia from Cicero in Norway. The results assist the municipality to design policy that will help manage the city’s water supplies in an increasing climate change-stressed future. The study focuses on identifying which incentives best motivate households of different income levels to reduce their consumption.

A large scale randomised control trial was implemented to test nine different behavioural inserts in monthly municipality bills on over 400,000 households over six months. Households in the control group did not receive a message. The messages, sent with people’s monthly utility bills, were framed in different ways: some had a financial threat to them, notifying people about how much money they would save through cutting their water use, or how much it would cost them if they didn’t. Some messages offered water-wise tips. Other messages compared people’s consumption to that of their neighbours’. Others tapped into intrinsic values and rallied people together under a ‘common good’ value system by appealing to people to save water for everyone’s benefit.

The research was funded jointly by the South African National Research Foundation, the Norwegian Research Council, Environment for Development, and the Water Research Commission.

All Treatment Groups

The future research avenues of the project are supported by the iCOMMS team from the Department of Information Systems at the University of Cape Town. As part of the project, it will be tested how to best incentivise water users to download an educational and consumption awareness app (DropDrop) that calculates projected water usage for the month and gives an estimate of the end-month water bill when entering readings from the municipality’s external water meter on a regular basis. The app also gives information on water conservation methods, the municipal contacts and information about the water system.

Moreover, the EPRU team in collaboration with Dr. Thinus Booysen, Associate Professor at the Electrical and Electronic Engineering Department at Stellenbosch University, will test how to best target the top water users to take up smart geyser devices such as Geasy. Geasy is an application, developed by Dr. Thinus Booysen, which can be attached to a household’s geyser to monitor and report water flow and usage through a smart phone app or computer programme. The application can detect bursts and automatically shuts down the flow of water. Further, it allows households to shut off electricity and water supply remotely in case they leave the house for an extended period of time and forgot to physically switch their geyser off.

Links to the news articles:

Carrot-or-stick to ‘nudge’ water-wise behaviour   

Public praise for water-wise behaviour: a lesson for city managers     

Public praise drives water-wise behaviour: A lesson for city managers    

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News | 3 July 2017