Why would Water Pollution be Detrimental to Populations? How does Water Pollution even Happen?

-Water Pollution will just give more Pressure on Water Suppliers, because there is Less Water to be Used -Fertilisers give out Phosphates and Nitrates [Pollutes Groundwater] Pollutants from Vehicles affect Water Sources and Factories will create Chemical Substances that affects Water Sources -Affecting the Water will then spread Diseases which will Restrict the Country from Development.