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The Rains Are Coming—Are Your Street-side Basin Inlets & Roof Gutters Ready or Clogged?

By Brad Lancaster

Like much of the country, we are in a record drought with high temperatures drying us out even more; stressing many shade plants, and threatening our cooling soil-carbon sponges—so we should be doing all we can to capture and hold on to cooling, life-enhancing moisture.

But even as the summer rains have begun in my home of Tucson, Arizona; many people who have installed passive street-runoff harvesting earthworks and/or roof-runoff-harvesting gutters and tanks are NOT ready to receive that free water because their basin inlets and roof gutters are clogged!

Are YOU ready or clogged?

Street-side tree basin inlets

BAD. Note how the street-side tree basin’s stormwater inlet—a curb core in the street curb—is clogged with debris as is the street gutter. Fix this!
Photo: Brad Lancaster
GOOD. Note how the street-side tree basin’s stormwater inlet—a curb core in the street curb—has now been cleared of debris, along with the street gutter. This was easily done with a shovel.
Blue arrow denotes water flow.
Note: ideally this basin would be larger to capture more water, but this is way better than no basin.
Photo: Brad Lancaster
GOOD, but note what was previously BAD on the basin-side of the street curb inlet.
The concrete curb is stained darker from the dirt that was removed to prepare the basin to receive the coming rains—there is now at least a 2-inch (50-mm) drop from the bottom of the street-curb core hole (or in another case could be a curb cut) to the top of the soil (or mulch) in the basin.
This way, the flow of the in-coming water will speed up, NOT slow down. So, sediment carried by the in-coming water will flow through, instead of settling out and clogging the inlet.
Blue arrows denote water flow.
Photo: Brad Lancaster
A well-built and planted street-side basin with cleared inlet and street gutter efficiently harvesting copious amounts of runoff.
Street gutter water flow is from left to right.
Photo: Brad Lancaster

More important points:

  • Water flows downhill, so make sure the elevation of the entire bottom of your street-side basin (and the surface of any mulch within it) is well-below the street gutter and inlet elevation. The deeper the basin the more water you can collect.
  • See here for important elevation and slope relationships within street-side basins, and tips on how you can expand their capacity.
  • Observe your street-side basin inlets during and after rains, and throughout the rainy season. Clean as necessary.
Curb core partially clogged by asphalt after a repaving project. Photo: Brad Lancaster
Clog now cleared. The City did not unclog the street-side water-harvesting basin inlets after multiple requests, so citizen activists fixed the problem by chipping away at the asphalt clogs with caliche digging bars (pointed steel digging bars). The chipped out asphalt pieces were then placed and compressed on the downstream side (right hand side in this case) of the curb core to encourage more flow through the core hole to the basin.
Blue arrows denote water flow.
Photo: Brad Lancaster

Roofs & their gutters

Around the world among rainwater-harvesting cultures, people clean their water catchments before the rain. Children often have this responsibility, sweeping a flat roof- or patio-catchment. At my home, the responsibility is mine.

I have to do this at the beginning of every rainy season because my roof and street gutters fill up with abundant pollen, pods, and leaves from overhanging trees (all of which makes for great soil-building and water-conserving mulch when relocated to the soil’s surface).

If you don’t clean your gutters, you’ll likely lose a lot of water you could’ve otherwise captured.

Gutters filled with debris from overhanging tree branches.
Photo taken at the beginning of the rainy season before gutters were cleaned.
If there is debris on the roof too, then clean the roof first, then clean your gutters.
Photo: Brad Lancaster

To help keep the debris collecting in your roof gutters from getting into your rainwater tank install a rainhead downspout inlet screen (and clean your gutters at the beginning of the rainy seasons).

For more

See the new, full-color, revised editions of Brad’s award-winning books
– available a deep discount, direct from Brad:

Book Cover #1

Volume 1

Essential reading!

See its eight guiding principles for the harvest of all waters, and an additional ten guiding principles specific to active systems harvesting rainwater in tanks.

Includes simple calculations enabling you to effectively size your systems for maximum performance.

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Book Cover #2

Volume 2

Lots of info on how to create street stormwater-harvesting basins/rain gardens, curb cuts, curb cores and a whole lot more!


Includes simple calculations for ideal sizing of your water-harvesting earthworks, and to estimate their cost of implementation.

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Neighborhood Food ForestryPassive SystemsStormwater & Street Runoff Harvesting