Water falls to the surface of the earth in the form of rain. Most of it evaporates or runs off to lower elevations, where it accumulates in ponds, lakes, rivers, and oceans. The water they contain is called surface water. Some water soaks into the ground, depending on the soil and rock cover on the surface. This water can saturate porous sediments and sedimentary rocks, such as sandstone and conglomerate. Layers of these rocks, filled with water, are called aquifers. The water they contain is called groundwater. Drinking water can come either from surface water or groundwater. Aquifers accumulate rainfall slowly. Their water may be hundreds or thousands of years old. Wells drilled into aquifers tap into this stored water. Because water accumulates and travels very slowly in an aquifer, contaminants that were added to surface water or materials buried below the surface may not appear in nearby well sites for years.

Contaminate To introduce or mix a substance into an otherwise pure substance, to pollute. Contamination When a pure substance has had impurities introduced into it. KEY VOCABULARY

Copy the following questions in your science notebook and provide a complete answer. After you have completed all the reading and analysis questions, be sure you have complete all the questions and vocabulary from the previous lesson The Hydrosphere/Water Cycle/Water Water Everywhere. After you have completed the above: Go to Lesson 30: Can You Taste The Difference and copy key Vocabulary