“Well, this is basically a trash can,” noted Arif Ullah, rainwater harvesting aficionado and Director of Programs at Citizens Committee for New York City, when handed our barrel-of-choice for our recent rainwater harvesting workshop, part of our East River State Park Summer Series. It was a trash can indeed - but that’s the beauty of DIY rainwater harvesting: you don’t need much more than a trash can to make it work!
Our other supplies included:
1 spigot (to connect to your hose or watering can)
1 valve with a gasket and nut
Fine mesh (for the top of the barrel to prevent leaves or mosquitoes from getting in)
Rope (to secure your barrel)
Cinder blocks (to raise the height of the barrel)
Additional pipe material (to connect your downspout or gutter with the barrel)
PVC elbows (if you want to adjust the direction of the water)
Drill (to puncture the barrel)
Total cost = $100
Arif began by explaining the long history of rainwater harvesting and how folks have collected much of the water they needed from rainwater for thousands of years. In recent decades, however, our water usage has soared. In 1900 - before the connection of the Croton and Catskill reservoirs - the average New Yorker used about 12 gallons of water a day. After connection, consumption spilled over the estimated 20 gallons per day, only finally peaking in 1991 at 200 gallons per person (an actually decreasing as water conservation technology was introduced). And for once, NYC’ers are actually the modest ones: the national average is 575 gallons. China’s average water usage, by contrast, is 85 gallons. That water includes the amount of water used to produce food and energy, fuel transportation, and that which returns to the system as waste.
And there’s another - very icky - downside to our thirsty habits: NYC and other old cities have a ‘combined sewer system’ meaning that the pipes that drain rainwater are the same as the ones that bring our sewage to treatment plants. When it rains, that system overflows, and made worse because of the high amount of ‘impervious’ surfaces (like concrete and paved roads).
Short story: your poop goes straight into the Hudson, Bronx, and East Rivers. Yum.
So, along with ‘green infrastructure’ (which includes planting trees and plants that can absorb a lot of water), harvesting rainwater reduces the amount of runoff and also curbs consumption when used in gardens or otherwise.
And harvesting rainwater does makes a difference: Arif explained that one could easily calculate the large amount of water collected off of a rooftop with this simple equation:
.62 x rainfall depth (e.g. 1 inch) x square footage of catchment area (e.g. rooftop)
= number of potential gallons harvested
We also discussed the mind-blowing square footage of all the rooftops in New York City, and the incredible positive impact this would have on the city’s water-related practices if we took advantage of those spaces. As the equation makes clear, placing our barrel under a downspout collects much more water than simply placing it under the sky.
Important elements of a DIY rainwater system are:
securing the barrel so it does not tip or spill;
positioning the barrel as close to the downspout opening as possible, or directing the spout directly into the barrel;
elevating the barrel to make water at the bottom, and the spigot, accessible;
creating an overflow spout;
closing the top with a fine mesh to keep out debris and mosquitoes;
winterizing the system once temperatures regularly drop below freezing
Perhaps most importantly: it’s easy! It’s so easy, in fact, we’re installing one in East River State Park. Come check it out! The Crew at Human Impacts is planning on assembling a short pamphlet about constructing rainwater harvesting systems in your own homes, but meanwhile, there are many tutorials and helpful articles available online.