Water hyacinth can pollute water. Water hyacinth reproduction speed, when it reproduces to a certain number will limit the flow of water and cover the surface of the water, the body of water can not be irradiated by sunlight and odor; at the same time it will make the dissolved oxygen content in the water to reduce and inhibit the growth of zooplankton, and the underwater animals will be difficult to breathe and a large number of deaths, and when those animals rot will seriously pollute the water.