Cistern / Rain Barrel

What is it?
Cisterns and rain barrels are storage tanks designed to capture and store stormwater for non-potable uses such as irrigation, toilet flushing, or industrial processes. Stormwater runoff is typically carried from roof areas to rain barrels or cisterns through roof gutters, downspouts, drains, and/or pipes. Screens on gutters and downspouts filter large sediment and debris from stormwater runoff before it enters the rain barrel or cistern. Depending on their size, these systems can provide a significant opportunity to use recycled rainwater in place of potable water, which can help save on your project’s long-term water use costs.

When is it used?

Rain barrels are typically located adjacent to buildings at single downspout locations, whereas cisterns may be located above or below ground and usually receive stormwater runoff from larger rooftops or ground-level impervious areas.

What are some key general considerations?

  • Consideration should be taken to ensure a stable path for overflows since cisterns are not typically designed for large storms.
  • Underground cisterns may need special permits and the location for overflows may also need approvals. Check with your local municipality.
  • A number of pollutants can be deposited on roofs and in parking lots through air deposition, bird droppings, other chemicals used to treat roof tiles, and oils from automobiles; therefore, it is important to never consume water collected without proper treatment in cisterns/rain barrels or use it to wash anything that will later be consumed.


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