How do you ensure that your drinking water is clean? Do you buy bottled water? Or do you simply drink straight from the tap because, though it may not be the cleanest water in the world, it is, at least, cleaned of anything that will make you sick?

Not everyone has safe water delivered to their homes through faucets. The water in a number of small, low-income communities in Mexico is not just dirty with grit, but contains toxic chemicals such as arsenic.

Scientists are experimenting with cleaning the water in these communities using a cactus that is common throughout Mexico. The cactus is the nopal cactus, otherwise known as prickly pear. Using this cactus to clean water isn't a new invention, but a practice that was used long ago throughout Latin America. People would first boil the plant, in part in order to eat it. They then poured the boiled water, which contained some of the cactus's goo, into their drinking water. The dirt and grit settles at the bottom, and the water on top is safe to drink.

This goo is called mucilage. It's the stuff that enables the living plant to store water. In tests, the mucilage proves capable of removing even arsenic. One small pad from a nopal cactus contains enough mucilage to treat about fifty to eighty gallons of water, enough to supply a family of five with clean water anywhere from two to five weeks.

Scientists hope to set up the first village-wide cactus filtration system in the next year in a Mexican town called Temamatla. If all goes well, cactus filtration systems could soon crop up all over Mexico.