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Polluted waterways increase water treatment costs.

In a study published by scientists at Yale University, Washington State University and The Nature Conservancy, the conversion of natural land cover to other uses, such as agriculture and housing, is found to increase the cost of water treatment as much as 50% in some major cities.

  • Why? Natural land cover provides important ecosystem services such as soil stabilization which minimizes erosion and sediment loading, i.e. the chance for sediments and nutrients from agricultural operations (such as nitrogen and phosphorus) to get into the water supply.

  • First, the scientists found a relationship between the water quality of water supply sources to the type of land use on land surrounding the water supply and the size of the population in the watershed.

  • Second, they demonstrate a statistical relationship between water quality degradation and increased water treatment costs by looking at the types and complexity of the water treatment technologies employed at water treatment plants.

  • Water treatment plants that take their source water from a more polluted waterbody are more likely to use more complex water treatment technologies and therefore not only incur greater capital costs but also greater operation and maintenance costs year to year.


- “Contamination of water pushes up costs, makes safe water scarcer: study,” 25 July 2016 accessible at

- “Estimating watershed degradation over the last century and its impact on water-treatment costs for the world’s large cities,” accessible at

- “What we’re doing to the environment may be costing us our drinking water,” 26 July 2016 accessible at

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