This includes the obvious things like rain and snowmelt, but it also covers things you might not expect, like condensation. In the video above, we share a fascinating story about a project in San Diego where the roof collected so much condensation that it created a constant stream of water down the spouts—even when there wasn’t a cloud in the sky! The city was convinced there was an illegal discharge happening, but it turned out to be perfectly natural precipitation.
It is just as important to know what stormwater is not. If you see someone washing cars in a parking lot or notice over-irrigation from sprinklers flooding a sidewalk, that isn’t stormwater. There is also a category called “permitted non-stormwater,” which includes necessary actions like flushing fire sprinkler systems. While these discharges are allowed, they don’t fall under the “stormwater” umbrella.
Understanding these distinctions is the first step in better managing our environment and staying compliant with local regulations. Check out the full video to hear more about that San Diego mystery and to get a clear handle on what is—and isn’t—flowing into our drains. Don’t be the one who gets this wrong!
Video Transcript
0:00 Intro
0:02 Stormwater is…
0:36 Stormwater is NOT…
0:00 Intro
What is stormwater?
0:02 Stormwater is…
Stormwater is any natural precipitation. Anything that you get from rain to condensation that accumulates on the roof. We have a project in San Diego that gets a lot of condensation on the roof, and the roof is very slick. Everything runs down the downspouts, and they actually get discharge from their downspouts through the parking lot even when there isn’t rain events.
The city kept inquiring, “Where’s all this water coming from?” and through a lot of investigation, it was coming off the roof and it is natural precipitation. It’s not an illicit discharge. We don’t get a lot of snow here, but snowmelt, etc., etc.
0:36 Stormwater is NOT…
What’s not stormwater is the person in the parking lot cleaning off all the cars, or over-irrigation that’s running over your landscape down your parking lot. You have permitted non-stormwater, which is like your fire sprinkler systems being flushed. Those are permitted discharges, but they’re not stormwater.
