Rainwater Harvesting for Drylands and Beyond by Brad Lancaster

Rainwater Harvesting Online Calculator


The goal is to use on-site non-potable water for your landscape instead of high-cost, imported potable (municipal/well) water.
Begin by entering values for the items below.

Water Income

Fill in the blanks below to determine how much rainwater and greywater can provide for your landscape.
Roof-Harvested Rainwater
Square feet of roof space (help)
Your site's average annual rainfall in inches (Bisbee - 20.7", Nogales - 19", Patagonia 17.78", Phoenix 7.40", Sierra Vista 14.24", Tucson -11.56", Wilcox - 13.4", Yuma - 3")
Where can I find this info? (opens in new window)
Check which applies to your site:
Rainwater is one of my water sources (others may be municipal water, well water, trucked in water, spring water. If one of those non-rainwater sources is your domestic water source for sinks, washing machine, and/or bath/shower, then the resulting greywater is counted as additional non-potable water income for use in the landscape)
Rainwater is my only source of water (in this case greywater is not counted as an additional water income or an expense, but an additional cycle/use of that rainwater if used to irrigate plantings)

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Umbrella Newsletter

The Umbrella: Winter 2019/2020

THE UMBRELLA: A catch-all of resources, events, media, and more from Brad Lancaster   Rain Planting E-BOOK now available! Rainwater Harvesting for Drylands and Beyond, Volume 1, 3rd Edition now available in E-BOOK format Plant the Rain gifts Get holidays gifts that spread the word and practice on how we can make the world a […]

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