Match each word with its definition:
1. A river, canal, or the flowing body of water that can be used for transportation.
2. Water that has been used by people in homes, factories, farms, and other places.
3. A way to solve a problem.
4. A system to remove unclean and contaminated substances like garbage or wastewater away from people for disposal or treatment.
5. Water that is below ground, under layers of rock, clay or sand.
6. Any material that, when added to water, soil, or air, makes it unsafe to use.
7. A large amount of water on or near the earth´s surface such as lake, river, pond, or ocean.
