Making your rainwater smart

(Rose Turner/Provided photo) The moisture sensor, planted in the garden near an outlet for the drip system.

Many people utilize rainwater collection systems to water their gardens, but Rose Turner at the Michigan Tech Sustainability Demonstration House has taken that idea one step further, programming her collection system to deliver water to the garden exactly when it’s needed.

Turner started with a typical rainwater system. It collects water from the roof of the SDH garage (The roof drain of the main house goes through the walls and directly into the ground, making it inaccessible for the project). The collection barrel was donated by mirainbarrel.com, who uses repurposed food-grade barrels and equips them with a spigot, overflow valve and filter screen.

The barrel was set up like any other, collecting water from the downspout with a hose that can be used to empty it onto the garden slightly downhill.

“There’s no pump required,” she said.

From there, Turner got smart. She put an electronically controlled valve on the end of the spigot, a moisture sensor in the soil of the garden, and connected them using a small programmable computer from Arduino.

(Rose Turner/Provided photo) The electronic valve and, in a waterproof containter, Arduino computer.

When the sensor notices soil moisture is below 30%, it opens the valve on the barrel, which lets water run through the hose for 30 seconds to a PVC drip system Turner also added to the garden. The sensor measures each minute, so at the next reading, the moisture content is high enough that the valve stays shut.

“As long as there’s water in the rain barrel, we’ll be good to go,” Turner said.


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