Water is of a great significance for people, since it is used for drinking and in food. The human organism must receive a certain amount of water every day. Otherwise, if an organism does not obtain the required amount of water for several days, it dies. It is obvious that the water consumed by the human organism should be pure. Water that contains any harmful bacteria or chemicals may cause various diseases of an organism or even death. Animal organisms depend on water in the same way. Organisms of some animals are more resistant to soiled water than human organisms. For instance, if a human drink from a puddle on a street, it is highly probable that one will get intoxicated, while a bird drank from the same puddle won't get any harm. However, if water contains some caustic chemicals of artificial or natural origins, it may significantly harm both humans and animals.

Water also serves as a major nutritive component for all plants. Water is used by a plant participating in a process of plant's development and growth. A plant obtains nutritive substances from the soil by absorbing water that contains these substances. Some deleterious chemicals being contained in water may blight a plant causing its growth stop or death.

Water serves as a habitat for various animals. These animals not only drink water, but they are in contact with water during all their lives. The more close is the contact with water, the more water influences on these organisms. Water interacts not only with these animals' digestive systems, but also with their external tissues, and the harmful chemicals the digestive system may successfully resist may injure tissues. Though, humans don't live in water, they spend some time in it, while taking a shower or swimming, so their tissues are also exposed to water.

It may be concluded, that all live organisms on Earth utterly depend on water, and if the water they consume is not clean, it reflects negatively on these organisms. Water refinery systems partially solve the problem for humans who are beyond such a barrier. However, people in non-developed countries do not necessarily have such refinery systems; they consume water directly from its natural sources, as do animals and plants. That is why it is highly important to make all natural water sources clean, so all live organisms on the planet have access to clean water.

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