Directly or indirectly, water affects all facets of life. Without it, there would be no vegetation on land, no oxygen for animals to breathe and the planet would look entirely different than it does today. Water is necessary keep people's bodies and the environment healthy and should be valued and protected as the precious resource it is.
Oxygen
植物生产呼吸空气值得赞赏，并为他们能够与水有关。通过一系列生化反应的，植物是能够在两个水分子（两个氢原子和每个分子中一个氧原子）转换成氧气。在陆地上，此过程中几乎完全被分解抵消，通过土壤中的微生物消耗氧并返回死有机物质回到大气中的二氧化碳。然而，氧气也通过在海洋藻类产生的，并且作为它们死亡和沉到海底，其生物质不通过耗氧过程分解。海洋藻类的这种墓葬是怎样被认为有导致我们的大气原来充氧。
天气
Global patterns of weather and precipitation are dictated by the movement, quantity and temperature of water, both in the ocean and in the atmosphere. As water vapor circulates through the atmosphere and into the oceans, it alters the temperature and pressure, resulting in wind and currents. As ocean currents move from the equator north and south to the poles, the water cools. The distribution in ocean temperature directly affects regional climate patterns. Because plants and animals have specific environmental requirements, temperature and rainfall determine that species are able to survive in a given location.
Agriculture
Americans depend on farmers to produce enough food to feed our increasing population. Aside from the vegetables on our plates, corn products are used in a variety of foods common to every supermarket. Ethanol extracted from corn has even been used as an alternative fuel. All of these everyday items rely directly on the amount of water they receive. Water is responsible for photosynthesis, which produces breathable oxygen, and also gives plants the vigor required to sustain their weight. Not enough water and the plants become stressed and eventually die. Too much water and the plants drown in the soil.
Fisheries
Just as humans require clean drinking water to maintain our health, fish and other aquatic organisms need clean water to survive. Water contaminated with mercury, polychlorinated biphenyls, PCBs, and other toxins can accumulate in the tissue of fish, which then gets transferred to humans during consumption. In September 2009, the U.S. Environmental Protection Agency released its Report on Fish Contamination in U.S. Lakes and Reservoirs. Their study found that nearly half of the sample lakes and reservoirs contained fish with mercury levels considered toxic to humans.
Sustainability
Because of the reliance on water to provide so many basic needs, water sustainability and conservation have been becoming increasingly important. Government bodies such as the U.S. Environmental Protection Agency and the U.S. Geological Survey are continuously monitoring streams, lakes, rivers and groundwater to ensure the highest quality drinking water for public health, to minimize environmental degradation and to improve efficiency in waste-water treatment.