Rainwater harvesting is using a building rooftop to channel rainwater into storage for later use. The land that buildings have a foundation on is considered an impervious surface because water cannot pass through it to get to the ground. Roads, sidewalks, and general development increases impervious surfaces that can lead to more flooding since rainwater cannot pass to the ground.
When rainwater is collected and stored safely for later use, it prevents this wasted water runoff that can’t pass through impervious cover. This sustainable water cycle is a more direct water source than using a utility water source.
Rainwater harvesting systems range from using your existing gutter system to channel the rainwater into a barrel to a large scale commercial system that can supply enough water to make a huge difference in water use.
The following is one example of a rainwater harvesting system that is in place for a two-story house.
The complete system consists of the gutter system channeling rainwater through (called the conveyance system) the first-flush drain, and then once that is complete, into the Pioneer Water Tank.
The first flush drain system for this project allows the first 20-gallons of rainwater to pass during a rainfall. This allows any debris or contaminates picked up on the roof or gutters to pass through and be drained out. Once it hits 20-gallons, the drain shuts off and the rainwater flows into the Pioneer Water Tank for the rest of the rainfall.
The Pioneer Water Tank has a pump to pull the rainwater back to the house for use, as well as an overflow pipe in case the tank becomes overfilled.
All of the gutters are organized into what downspout they lead to. The downspouts are then channeled into the underground receiving pipe that then leads to the first-flush, and then the Pioneer Water Tank.
The gutter system leading to the underground piping system is shown without the house.
Underneath the Pioneer Water Tank, the rainwater from the gutters leads at first through the first flush drain and then into the tank once that’s complete. The outflow pipe is pumped back to the house. Outside of the Pioneer Water Tank is the overflow pipe that can handle if the tank takes on too much rainwater to prevent overfilling.