Stormwater, for reasons we will discuss below, is an increasingly pressing issue of our times. Despite this, our public education system has a relatively scattered approach to teaching the subject as well as ways to reduce and manage it.
For that reason, definitions are called for in any discussion of stormwater harvesting. When most people hear the phrase “stormwater,” they naturally assume it must have to do with an actual storm, but that’s not the case. In actuality, stormwater can come from any type of precipitation that falls and then gather. That includes:
- Rain that falls in the area
- Rain that falls elsewhere but travels into the area through waterways or over pavement and other manmade surfaces
- Snowmelt, where the “stormwater” fell as snow at elevation and does not reach the water table until it melts in spring or summer
- Any combination of the above
See, stormwater and floodwater are not the same. Every time you look out the window while it’s raining and see the water moving in runnels toward a gutter, that’s stormwater. The experts sum it up best:
“When rain, snow, or another type of precipitation hits a surface, it becomes stormwater,” explains North Carolina’s Clean Water Education Partnership. “In natural landscapes, stormwater gets soaked up into the ground or falls directly into waterbodies. However, when rain or water hit hard surfaces like pavement, sidewalks, and roofs it creates stormwater runoff.”
That runoff often moves through cities unimpeded, flowing over hard – also referred to as impermeable or impervious, meaning nothing can get through – surfaces. Let’s just say stormwater gives new meaning to that oft-repeated childhood phrase: Rain, rain, go away.
Actually, it’s not the rain we want to go away, per se. It’s the problem that rain often brings to properties across the world: massive runoff and pollution, among other risks. Let’s take a look at those now.
What Is Stormwater Harvesting?
“A stormwater harvest and reuse system is a constructed system that captures and retains stormwater for beneficial use at a different time or place than when or where the stormwater was generated,” explains the state of Minnesota. Their definition is specific to a system that stores stormwater in cisterns, which is indeed a wonderful way to reuse rainfall and help the world.
However, there are many other ways to harvest stormwater other than cisterns, and we will take a look at these throughout the book. In brief, you can:
- Use living roofs as filtration systems to capture stormwater that is cleaned by plant roots and collected beneath them for later use, either by the green roof plants or by someone else
- Install retention and detention ponds that capture rain, snow, and runoff, then funnel that water toward landscaping, home use, aquifer recharge, or wetlands
- “Harvest” stormwater by planting gardens or raised boxes that absorb it as it falls
Though the latter is technically a stormwater management tactic and not a harvesting one – because you don’t hang onto the water for later use – the strategies are enough alike that they’re worth considering here.
However, while this eBook will look at stormwater management strategies in general, we will focus on stormwater harvesting and the emphasis on reuse inherent in the concept. Before we do that, though, let’s talk about why this matters to you and the world.
