If you're looking for things specific to water, you might want to change your keyword search from "water" to "hydroelectric" or something like that. You'll get much more beneficial search results.
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The first law of thermodynamics is you do NOT talk about thermodynamics.
Can you provide more information including education level of the project, project details and ideas you already have so we don't waste our and your time making suggestions based on guesses such as
"An analysis of dietary fibre intake and bowel movements to help reduce waste water consumption"
A potentially good PhD level project but probably not that helpful to you.