Matt Damon is working on a book about access to clean water

The authors - who met at a Clinton Global Initiative event in 2008 - said in a statement: "We’re excited to have written this book together, and we can’t wait to share the story of what happens when a movie actor and a civil engineer team up to try and take on the global water crisis — the stumbles and obstacles, the breakthroughs and big gains, and the incredible people we met along the way.”

Matt and Gary agreed that their “journey” writing the book had “proved” two things; the ability to fix the issue and how to do it.

They continued: “Our journey has proved two things: one, solving the water crisis is possible — within our lifetimes. And two, the key is unleashing the incredible determination and resourcefulness of the people who are fighting every day for essentials like safe water and sanitation.”

Portofolio, the book’s publisher and an imprint of Penguin Random House said of the book: "[It will showcase] the challenges of building and scaling market-based financial solutions to make clean water and sanitation more accessible.

"And ultimately, it’s the story of how communities and individuals can be empowered to make long-lasting investments in their own well-being.”

The 51-year-old actor has been a spokesperson for water sanitation since a 2006visit to Zambia, while Gary is the founder of charities WaterEquity and Water.org.