Rearrange the given sentences in a meaningful order.

A. There is no physical substance humans require more than freshwater: without water, we can only survive a few hellish days.

B. Soils, microorganisms, and plant roots all play a role in filtering and recycling out pollutants with a price far cheaper than building a water filtration plant.

C. Healthy freshwater ecosystems—watersheds, wetlands, and forests—naturally clean pollution and toxins from water. 

D. While pollution and overuse have threatened many of the world’s drinking water sources, nature has an old-fashioned solution, at least, to pollution.

E. According to research, the more biodiverse the ecosystem, the faster and more efficiently water is purified.