One of the most important features of our Center for Community Forestry is something no one ever sees. It’s the TreePeople cistern, a 216,000-gallon underground storage tank, where we save rainwater collected from the Center’s rooftops and Parking Grove.

The water is filtered and then stored in the cistern for use in dry months, when the vegetation on our site must be irrigated to survive.

Technology inspired by a natural forest

In a natural forest, trees help the ground absorb and hold rainwater. This enables the water to percolate slowly down to the aquifer, where it replenishes groundwater supplies – a source of water for human use.

Our cistern uses some very simple technology to mimic the water-capturing processes of a forest. If more homes and business in Southern California harvested rainwater this way, it would decrease the amount of polluted runoff that ends up in our ocean.

It would also reduce the city's need to import 85 percent of its usable water, which comes at a high cost to consumers, the environment and the communities in which that water originated.

How big is the cistern?

The TreePeople cistern is a circular tank, 70 feet in diameter and 8 feet deep. It is made of concrete and has a steel-reinforced roof held up by concrete pillars. This enables it to withstand the weight of fire trucks in times of emergency – when the water in the cistern can be used by our local fire department.

Build a virtual cistern

Use our interactive cistern model to build a virtual cistern and test how it would have performed during nine different rainy seasons in Los Angeles.