Here are some water treatment methods, depending on your area and type of water:
• In areas with naturally acidic water (such as surface rainfall in upland mountains of igneous rocks), the water can sometimes actually dissolve the lead from any lead pipes that carry it. Plumbo-solvency (the addition of small quantities of phosphate ion that increases the pH level) can help by creating insoluble lead salts on the inner surfaces of the pipes.
• Some groundwater sources contain radioactive radium. The area north of the Illinois River in Illinois is one example. Radium can be removed by ion exchange, or by water conditioning.
• Desalination, or filtering salty ocean water into drinkable fresh water, is expensive, but an increasingly common treatment method for people living along the shores of Florida and California. Although new technology has cut the cost of filtering ocean water in half since 1990, the process uses large amounts of electricity, and can cost up to three times more than other methods. Direct contact membrane distillation (DCMD) is the most common form of desalination, where heated seawater is passed along the surface of a hydrophobic polymer membrane. Evaporated water passes from the hot side through pores in the membrane into a stream of cold pure water on the other side. The difference in vapor pressure between the hot and cold side helps to push water molecules through.
If your local water is not treated commercially by a water treatment facility, it usually comes from a public or private well or other public, non-treated system that may contain contaminants. In such areas, the local public health agency makes recommendations as to whether groundwater can be safely stored, for how long, and how to treat it. There are many popular methods for purifying the water in these local private supplies.
• Distillation involves boiling the water to produce water vapor. The vapor contacts a cool surface where it condenses as a liquid. Because the solutes are not normally vaporized, they remain in the boiling solution. 99.9% pure water can be obtained by distillation.
• Reverse osmosis: Mechanical pressure is applied to an impure solution to force pure water through a semi-permeable membrane. Reverse osmosis is theoretically one of the most thorough methods of water purification, although perfect semi-permeable membranes are difficult to create. Unless membranes are well-maintained, algae and other life forms can colonize them.
• Gas Hydrate Crystals Centrifuge method. When carbon dioxide gas is mixed with contaminated water at high pressure and low temperature, gas hydrate crystals will form that contain only clean water. Since the contaminated water is in liquid form, a centrifuge is used to separate the crystals and the contaminated water.