Water Harvesting: Active Collection for Later Use


Rainwater storage tank made from culvert pipe in Arizona. Photo credit: Susan Buffler in Landscape Water Conservation Flickr CC BY-NC-SA 2.0


Water harvesting for later use involves collecting rainwater in a tank of some kind. Tanks can be as simple as a sturdy garbage can under a downspout or as complex as a large underground tank and pump.

Why Collect Water for Later Use?

  • Can reduce water bills
  • Saves a valuable resource
  • Rainwater is free of salts and other minerals or chemicals that may be harmful to plants
  • Reduces pollutants to area streams and rivers by keeping water on site and off impervious paved areas

Tips for Collecting Water for Later Use

  • Know how much water is going to come off of the roof or other surface. This will determine tank size
  • Provide an overflow outlet or link to another tank
  • Use a filter to collect debris from roof runoff
  • Use a purification system if using for drinking water
  • Metal roofs work best
  • Check local ordinances. Rainwater collection for storage and reuse is restricted or illegal in certain states, counties and cities
  • Use opaque dark colored tanks to reduce algae growth
  • Use HDPE pipe for above ground tanks. Avoid PVC pipe which degrades in sunlight

Additional Resources:

An Introduction to Green Infrastructure Practices  
Regulations and Statutes


Colorado – Graywater Reuse and Rainwater Harvesting
Montana – Rainwater Harvesting Systems for Montana
Nevada – Make Each Drop Count: Harvest Water for the Landscape
Washington – Homeowner Practices for Managing Rain


Rain Barrels Part I: How to Build a Rain Barrel
Rain Barrels Part II: How to Build a Rain Barrel


Alabama – Rainwater Harvesting for Irrigation Water


Arizona – Rainwater Harvesting for Drylands and Beyond
Texas – Rainwater Harvesting