What I didn't realize, is there's a huge difference between non-renewable water that's in lakes, underground aquifers and glaciers, and what is actually considered renewable. Renewable water is water that generally operates on an annual cycle where it falls from the atmosphere as precipitation, runs off the land surface in rivers and streams that eventually reach the ocean, and is then evaporated by solar energy and returned to the atmosphere to fall again as precipitation. When viewed in this way our supply of the world's renewable water is only at 7%.
Thanks to the various continental divides that ensure all water flows downhill, more than half of our renewable water flows into the Arctic Ocean and Hudson's Bay, reducing even further the amount of water available to the rest of the country where most folks live. But, just because the water is renewable doesn't mean it's drinkable. "Water, water everywhere but not a drop to drink" said the Ancient Mariner in Samuel Taylor Coleridge's epic poem that could just as easily apply to much of Canada where, to our great shame, one in five First Nations people who do live up North lack access to clean, safe, and sustainable drinking water.
Non-renewable water can take up to millions of years to accumulate and, over using it, could mean ages again before it ever refills. This is the current situation with the Ogallala aquifer in the U.S. midwest, one of the world's largest, which is rapidly being drained for drinking water and by irrigation for the farming industry. In Canada our non-renewable water could also start to disappear with our glaciers melting as a result of global warming or if we started to drain our lakes by exporting water to the U.S. which has been proposed numerous times over the years.