Cistern

Cisterns 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 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.

Considerations:

• 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. Therefore, cistern water should never be consumed without proper treatment.

Cost: Cost varies by size of cistern. Cisterns are generally more expensive per gallon of water captured compared to other BMPs. They are ideal for smaller projects where roof capture is desired. Depending on their size, cisterns 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.

Maintenance: Regular maintenance activities include flushing, filter cleaning, and debris removal. See manufacturer guidelines for specific procedures.

Aboveground Cistern Schematic
Image Credit: NJ BMP Manual, 2020