Susan MacKay thinks her company can help solve Earth’s water crisis … and Google thinks she might be right.

Google executives recently picked MacKay, CEO of Orono-based Cerahelix, as a finalist in its global competition for world-changing ideas — a contest the Silicon Valley giant calls “Solve for X.”

MacKay’s “moonshot” — the term Google uses to describe these Earth-shattering ideas — is to tackle the global issue of water scarcity by using nanotechnology to develop a new type of filtration devices that would allow industrial waste water to be recycled and reused on site rather than companies drawing more fresh water from existing resources.

Looking at Earth from space, it’d be tough to convince an alien that our planet is facing a scarcity of water. But we are, MacKay says. Seventy-one percent of Earth’s surface may be covered by water, but only 3 percent of the planet’s water is usable by humans — i.e., fresh water — and of that amount, less than 1 percent is accessible by humans, according to MacKay. The rest is captured in the ice caps or under the soil.

There are towns in the United States that have run out of water. California is currently facing one of the most severe droughts on record. Water resources are fought over in areas of developing countries. In fact, 1/3 of the world’s population is currently experiencing what MacKey calls “water stress” — a share of the population that is expected to reach 2/3 in 10 years, she says.

There are two ways to remove the existing stress on the planet’s fresh water resources, according to MacKay. Convert salt water to fresh water, or filter, treat and reuse the vast amounts of fresh water being used in industrial processes like fracking for natural gas. As it turns out, recycling fresh water in urban areas is four times more energy efficient than desalination, according to MacKay, who has a Ph.D. in chemistry from UNC Chapel Hill and 20 years experience in materials research.

“What the world really needs is new technologies that can now treat this water to the level needed to create clean safe drinking water for everyone,” she says.

At Cerahelix, which MacKay founded in 2011, she and her small team in Orono have developed a next-generation ceramic filtration device created by adding DNA to the original material, then removing it in a process that leaves DNA-sized pores through which the water will flow.  When trying to remove chemicals and other pollutants from water, a filtration device is only as good as its pores are small — and you can’t get much smaller than DNA.

The primary industry MacKay is targeting with the new filters is the oil and gas industry, which uses vast amounts of fresh water in the process used to release and collect underground natural gas deposits, known as fracking. Cerahelix is in the process of commercializing its products and has had success in its trials, MacKay says.

MacKay pitched her company’s vision at a preliminary Solve for X competition in January in Somerville, Massachusetts. After that event, Google executives picked MacKay and three other entrepreneurs from a pool of 76 applicants to pitch at the East Coast finals, which were held in February at Rutgers University in New Jersey. The Rutgers event was one of only two regional events in the United States. There are 10 other regions around the world, not all of which have held their final pitching events yet. Once all the regional events have happened, Google will pick the winners.

What is still unknown to MacKay is Google’s “endgame” with this contest. MacKay says the process has been “mysterious” so far. She thinks Google will promote the finalists in some way, either by providing direct financial support or making introductions to the people who could help the business reach its goals, but no one has told her definitely.

“I think it will depend on which ones they back and what those ideas need to succeed,” MacKay says.

I reached out to Google myself to see if I could find out anything more about the competition, but no one got back to me.

Whatever happens, MacKay has already benefited from participating in Solve for X and pitching her business at Rutgers. She’s currently raising her first round of outside investment — to date, Cerahelix has relied on $2 million in federal grants to complete the research and development — and has already made connections with several potential investors in the New Jersey and New York areas.

I’ll update readers when Google picks its final winners.

You can check out the existing moonshots on the Solve for X website. If you want to learn more about MacKay’s moonshot, watch her pitch at Rutgers: