 The governments of numerous countries have striven to find solutions to reduce this problem.Many pollutants threaten water supplies, but the most widespread, especially in developing countries, is the discharge of raw sewage into natural waters; this method of sewage disposal is the most common method in underdeveloped countries, but also is prevalent in quasi-developed countries such as China, India, Nepal and Iran.Sewage, sludge, garbage, and even toxic pollutants are all dumped into the water.