As surface water is water denotes that openly and unattached to the earth's surface is. These include surface waters such as rivers or lakes (see also receiving waters ) and rainwater that has not yet seeped away or has run off into receiving waters (see also puddles ) . The opposite of surface water is groundwater .
Surface water is often rich in suspended solids or solutes . Since both the suspended particles and the solution cargo pollutants may contain surface water is in principle only after treatment as drinking or industrial water used for industrial purposes.
A categorization of the different surface waters and their system is defined in an EU regulation. It differentiates between: rivers, lakes, transitional waters and coastal waters.