Wetlands—Nature’s Water Filters

Wetlands are an important feature on Canada’s many landscapes. As part of Canada’s vast water systems, wetlands play the role of nature’s water filter. They have the amazing ability to remove harmful impurities from the water we drink and use every day—long before it reaches the pipes that carry it to our homes.

Wetlands exist as part of a watershed. Watersheds are landscape-level systems through which water flows and drains. Lakes, rivers and wetlands—as well as the land that separates them—are all part of these systems.

These systems are very large and complex. As a result, there are lots of ways that water can become polluted from human activity along the way. Wetlands, and the plants, microbes and wildlife that inhabit them, are the filters in this process.

One way that wetlands clean water is to clean out excess nutrients. Nutrients like phosphorus and nitrogen can enter the water system from agriculture and industrial development and can seriously pollute water and harm the life that depends on it.

Watersheds are landscape-level systems through which water drains and flows. Wetlands are an important part of watersheds, as they naturally filter water that passes through them.

Research has shown that the sediments and organisms that live in wetlands can trap, breakdown or absorb these nutrients. In fact, up to 92 per cent of phosphorus and 95 per cent of nitrogen draining from the surrounding watershed can be removed from water passing through a wetland!

Another way that wetlands filter water is to trap and absorb harmful bacteria. Because wetlands are full of life, they are home to a very complex food chain. At the bottom of the food chain are the various microbes and bacteria, which invertebrates, such as insects, feed on. That’s why wetlands can filter up to 90 per cent of bacteria in the water.

Wetlands also trap sediments—up to 70 per cent of sediments found in runoff, according to research. This is important because it helps to purify the water, as well as lessen the impact of erosion.

For these reasons, wetlands are known as nature’s finest water filters! In fact, wetlands are so good at this process that specially constructed wetlands have been used to treat wastewater (sewage) in Europe for over 50 years.

Wetlands are a key link in the water system chain. Canadians have made it clear that water is one of our most important environmental issues. Wetland and water conservation is critical if we want to keep our water healthy. The next time you take a drink of water, think about how Canada’s wetlands help to keep our water clean.

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