The best solution is prevention
Just as there is no single source of water pollution, there is no single answer to solve the problem. Once water has become contaminated, it is very difficult, if not impossible, to clean. Surface water flows quickly, and a pollutant will generally be diluted as it enters larger bodies of water. However, even large bodies of water, such as the Gulf of Mexico near the mouth of the Mississippi River, cannot tolerate many years of eroded soils, increased nutrients, and chemical pollution.
Groundwater, however, moves very slowly. In heavy clay layers or in bedrock, water might only move several inches per year. Even in gravel and sand aquifers, groundwater may move only several hundred to a thousand feet per year. Once the water is polluted, it will spread out slowly over a period of many years.
Some problems, such as hazardous waste sites, require massive, expensive clean-up procedures. With other problems, such as large manure spills, little can be done but let the wastes become diluted as they reach larger bodies of water.
However, there are steps to take to reduce some of the most serious problems such as siltation from erosion is passed legislative law to warn deterrent