Boiling is a great way to kill bacteria, viruses, and parasites from water. Fill a pot with water and heat it over medium-high heat, or over a fire. Bring the water to a boil and let it sit at a rolling boil for about 10 minutes. Let the water cool before drinking.  Water purification typically happens after three to five minutes, but especially at higher elevations, you must boil the water for longer. Boiling alone will not remove heavy metals or chemical contaminants from water, but boiling the water with the inside of a cactus could remove additional pollutants, such as arsenic. SODIS is an acronym for solar water disinfection, and when done properly, it’s a very effective method for killing pathogens in water. Fill a clear and smooth plastic bottle with water. Twist on the lid, and place the bottle on its side in direct sunlight for six hours to kill parasites, bacteria, and viruses. This method works because the plastic acts to trap heat from the sun inside the bottle, and the UVA rays pasteurize the water.
Boil the water. Use the SODIS method.