How one sticker helped save 6,720 cubic meters of water

Updated: Aug 18, 2020

Fresh water is one of the most critical issues of our century – especially when we look at the dry summer we’re experiencing in Europe and in other regions of the globe. That’s old news.

Several strategies have been used to promote water conservation in urban areas across the world but we will be looking at a particularly efficient one developed in Costa Rica by the World Bank and the Think Tank ideas 4. A behavioral approach to water conservation.

The experiment happened in Belen, in Costa Rica in 2014 and here is the story.


  • Promote water consumption reduction.

Key Findings from focus groups:

  • Few residents believed that they themselves needed to use less water.

They were broadly aware that water was scarce and that it ought to be used appropriately rather than being wasted but they were seeing their water consumption

as “a necessary evil.”

  • Residents did not know how much water they themselves used

Several people pointed out that the billed amount included charges for both water and sanitation services, and so the amount of water consumed was not salient.

  • Residents could not evaluate whether a given level of water consumption was too high or reasonable

They lacked a benchmark against which to compare their own consumption

  • ·Few participants could identify concrete steps they could take to reduce water consumption

They lacked knowledge and information on how to act.

THE Nudge:

A two-step approach:

1) Leveraging social norms intervention

To respond to the bottlenecks: problem of salience, absence of benchmark, the team designed stickers that would give people feedback about their water consumption relative to an appropriate reference point: their neighbours.

2) Providing a step by step plan to save water

The intervention was also (“Plan-Making”) built on the literature on goal-setting, and planning prompts to address the absence of a clear plan for saving water and the related lack of information about how to do so.

Results (by extrapolation):

By using reference points, the team has capitalised on the social norm levers to trigger a specific behaviour. By providing a list of concrete actions, they also removed the friction of thinking and research efforts. This nudge has delivered outstanding results.

  • A 5,6% water reduction compared to the group that has not been nudged.

  • 6 720 cubic meters saved per month

  • An equivalent of 188 888 showers or 220 000 dishwasher loads.

Simple right? So why not doing this more often?

If you would like to read the full report click here.

Share your ideas on how you could use the principle of this Nudge for your own or other good causes!

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