Water purification is the removal of contaminants from untreated water to produce drinking water that is pure enough for its intended use, most commonly human consumption. Substances that are removed during the process of drinking water treatment include bacteria, algae, viruses, fungi, minerals such as iron and sulphur, and man-made chemical pollutants. There are a number of methods of water filtration, each with varying degrees of effectiveness, and varying costs. The general purpose of filtering water is to improve the water’s hygiene and aesthetic qualities. But the most popular way of water treatment is still slaw sand water filters. They have been used for over 100 years to treat waste water. They are generally used on a larger scale to treat a water supply for a whole community, and will be custom made. Most units require a constant flow of water to work correctly, and so wouldn’t be suitable for well water treatment. However, recently a Canadian scientist, David Manz developed an intermitent unit. You can buy pre-built commercial units for home use which are typically used with swimming pool pumps.