The following are sources of pure water except

When we talk about sources of pure water, we are referring to origins where water is naturally found in a state suitable for drinking, without contamination. Let's analyze the sources listed:

• Rain: Rainwater is generally considered pure as it comes directly from the atmosphere, free of most contaminants. It hasn't picked up pollutants from the ground yet, which makes it a viable source of pure water.
• Stream: Streams consist of water that flows naturally over the Earth’s surface. They are often sourced from rainfall or groundwater and generally contain low levels of contaminants, though the purity can vary based on location and pollutant exposure. It is typically cleaner than rivers or lakes.
• River: Rivers are larger bodies of flowing water. While they can start relatively clean, as rivers travel, they often collect pollutants from industrial discharge, agricultural runoff, and urban areas. This means that river water is rarely considered pure without treatment.
• Sewage: Sewage is a collection of wastewater from domestic, industrial, and stormwater sources. It contains a high level of organic waste, chemicals, and other pollutants. Therefore, sewage is definitely not a source of pure water.

Given this analysis, **sewage** is the one that is not a source of pure water by any means. It requires extensive treatment to remove contaminants before it can be considered safe or pure for consumption or release back into the environment.