Rainwater Harvesting at the Wildflower Center

by | Aug 5, 2005 | Pressroom

The Lady Bird Johnson Wildflower Center lives its mission by serving as a model for total resource conservation. The Center’s rainwater harvesting system is an integral part of its architecture and demonstrates the importance of connecting human culture with the natural world. The collection system was installed in 1995 not only to conserve water, but to serve as a public education tool. The Center collects water from 17,000 square feet of roof space and can store more than 60,000 gallons in on-site cisterns.

How is the water used?

  • The collected rainwater provides approximately 10 – 15% of the Center’s yearly water needs for irrigation of gardens and landscaping
  • The total storage capacity of the various cisterns and storage tanks is more than 60,000 gallons.

How much water can the Wildflower Center’s system collect and store?

Central irrigation rooftop system

  • Rainwater is collected from metal rooftops totaling nearly 17,000 square feet
  • Two cisterns with a capacity of 20,000 gallons each and the Tower cistern which can store nearly 5,000 gallons
  • Approximately 10,600 gallons of water is collected per inch of rain
  • With an average rainfall of 30 inches per year, this rooftop system can collect approximately 300,000 gallons of rainwater per year

Entry cistern system

  • Collection system is fed by 1,167 square feet of metal roof
  • Cistern capacity is approximately 12,000 gallons
  • This cistern can collect 700 gallons per inch of rain, or approximately 21,000 gallons per year.

Children’s area cistern

  • Collects water from 672 square feet of roof
  • Cistern capacity is 3,000 gallons
  • Approximately 420 gallons per inch of rain, to collect 12,600 gallons per year

Cistern System

  • Capacity as follows: 5 cisterns that hold a total of approximately 65,000 gallons
    • 2 large cisterns hold 20,000 gallons each
    • 3rd cistern holds 5,000 gallons
    • Entry Cistern holds 12,000 gallons
    • Little House Cistern holds 3,000 gallons
    • 2 transfer tanks
  • All are above ground except for the transfer station, which is underground
  • The Tower and Entry Cisterns are constructed from standing pipes on a cement foundation and covered in limestone and mortar.
  • The largest cistern is made of fiberglass and the Children’s area cistern is galvanized metal


  • Municipal supply is linked at the cisterns with backflow devices to prevent contamination of potable water
  • Option to manually turn to city water that would bypass the collection system and go right into the irrigation spigots