Cistern to collect rainwater from your roof

A cistern is a large tank that collects rainwater from your roof. Cisterns are most appropriate when you have significant outdoor water needs. They can be aboveground or buried underground.

Rainwater can be used for many activities, including:

  • Watering plants (gardens, lawn)
  • Washing your car
  • Washing the dog
  • Flushing toilets (requires additional permits and plumbing)

Benefits of a Cistern

  • Savings on your water bill by using rainwater instead of drinking water for irrigation.
  • Relief from drainage problems and basement flooding issues by collecting and containing much of the roof runoff.
  • A reduction in stormwater runoff from your property, which reduces the amount of sediment and other pollutants that would be washed away with the runoff into nearby storm drains and local streams.
  • Groundwater recharge. The slow release of the water allows it to soak into the ground, which supplies water to local streams in between storms.


Cisterns come in a variety of sizes. Select a cistern based on an estimate of how much runoff is generated by your home and how much water you can reuse on your property. Most cistern systems include a pump to provide sufficient water pressure to use the water. Locate the cistern in a shady or protected location to deter algae growth in the tank. Darker-colored tanks also help prevent algae growth.


It’s best to regularly use the water in your cistern to keep the system operating well and ensure there is capacity to store water from the next storm. It’s recommended to disconnect and drain the tank prior to the first winter freeze.